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First Human to Walk on the Moon Turns 80

Henry Wadsworth Longfellow's most poignant sonnet "Mezzo Cammin" starts:

Half of my life is gone, and I have let
The years slip from me and have not fulfilled
The aspiration of my youth, [...]

Those select few among us who can claim that this does not apply to them are really lucky. Among them is Neil Armstrong, who, in July 20, 1969 became the first human to set foot on the Moon - the culmination of the greatest scientific venture ever undertaken by man and the most significant single event in human history.

Of course, I don't know whether Neil Armstrong's childhood dream was to fly to the Moon. Back in the 1930s, the very concept of spaceflight must have appeared like a mere flight of fantasy. Certainly nothing sensible people should take seriously. But guess what? A mere three decades later, Gagarin's first space flight proved the sensible people wrong. Dreamers 1, realists 0.

Neil Alden Armstrong was born on August 5, 1930 near Wapakoneta (wherever that is), Ohio, United States of America, The Earth, the Solar System, the Orion branch, the Milky Way, the Universe. That makes him 38 when he entered the history books.

Today, August 5, 2010, over 41 years later, Armstrong turned 80 and that 7 year old boy who, back in the summer of 1969, wheedled and cajoled and used every trick in the book to get his Mom to allow him to stay up late and watch the first Moon landing on TV still hasn't flown to space and probably never will. But flying into space sure has been the aspiration of my youth.

Happy birthday, Neil. Man, I envy you.

And, in case I forgot to say it back then, or ever since: Thanks, Mom. For everything.

Aurora Alert Tonight, August 4/5

Pow! After a long stretch of uncanny calm the Sun erupted in a violent flurry of activity with a massive coronal mass ejection (CME) on August 1. This belched a stream of solar wind our way, vastly increasing the number of charged particles trapped in the Earth's magnetosphere.

The August 1 Coronal MassEjection, with the visible face of the Sun bursting into turmoil, shown in the extreme ultraviolet band in this image from the Solar Dynamics Observatory. Source: NASA/SDO

At high latitudes, this led to magnificent auroras (or "polar lights") observed mostly over North America yesterday. There may be more to come, another CME may be brewing today, so we might have another fine display of celestial fireworks tonight.

Weather permitting, why not step out and have a look tonight? I certainly will. Geomagnetic storms and auroras are famously difficult to predict, but I'll give it a try.

A panorama shot of aurora borealis over Lake Superior by Shawn Malone. Image shown on spaceweather.com

More information

Spaceweather.com, with up-to-date information on the Sun's well-being and the latest aurora pictures

August 2010 Aurora Photo Gallery on spaceweather.com

Aurora Forecast web site, Geophysical Institute, University of Alaska, Fairbanks AK

Nigeria: Emerging Nation Status Soon?

Ask people what their first thought is when they hear the word "Nigeria" and what will they answer? More likely than not, the first association they make is ye olde "419 Scam", a rip-off that typically starts with an e-mail that should have been deleted unread. For sure not only Nigerian internet criminals use this ploy, but the "Nigeria connection" did originally invent it. Sadly, this is not just the first, but also the only thing many people can think of. But I think Nigeria is worth taking a closer look at and here's why ...

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Let me state two things right away: Yes, I am aware that I am taking some recourse to generalisations. But this is a blog article, not a scientific treatise - it's just not possible to the level of detail the subject would warrant. And no, I certainly cannot claim to be an expert on Africa or Nigeria. I'm only an engineer who is interested in how people and nations use technology to further their development. And I'm very interested - this has to do with my personal history - in how nations overcome pernicious poverty and lack of economic development.

I have always been interested in Nigeria. I never accepted the popular pessimism concerning African development. On the contrary: I believe that Africa, led by those countries that benefit from certain advantages, will very soon make a dramatic recovery from that vicious circle of poverty, violence and corruption that unfortunately still to a large extent is typical of the continent's situation.

Obviously I don't expect that this recovery will take place at the same pace everywhere or that there won't be setbacks. Given the enormous ethnic, religious, cultural and economic diversities, why should everything run smoothly? And I also don't think that Africa's development will follow that of other emerging nations. Africa is different, so its development will be different. Just look at today's coming economic giants: China, India and Brazil. Each of these is following its own path.

I am convinced that the Federal Republic of Nigeria will be among the African countries that benefit from special advantages. With 155 million inhabitants (in 2009), Nigeria is by far the most populous country in Africa; it is number 8 in the world - ahead of Russia and Japan. After having been ruled by military dictators for more than three decades, democratisation began in 1999. Admittedly, much remains to be done.

Nigeria possesses vast oil resources and is a member of OPEC. In the past decade, rising crude oil prices have fueled considerable economic growth of 3-6% per year. This does not translate into an equivalent rise in public wealth - due to the annual population growth of 2% ... and also the still rampant corruption. Furthermore, crude oil accounts for the vast majority of Nigeria's exports. That is a legacy of the military rule. Nigeria will have to diversify its economy to maintain sustainable growth.

It is interesting to observe which technologies are used in developing nations. These often do not simply emulate the developed world. Technology is inherently conservative; it is very hard to replace obsolete but widespread technical standards. But countries that do not yet have a lot of technological infrastructure in place are free leap-frog intermediate steps and pioneer completely new solutions. In some African countries, cellular phones are used like a portable bank account and electronic purse - by individuals who are not considered as account-worthy customers by banks. I think this is great. When technology joins forces with necessity, anything becomes possible.

Nigeria in Space

I am a spacecraft engineer, therefore, unsurprisingly, I am interested in space technology. I think that the way a nation approaches space is a sort of litmus test that indicates how serious its leaders are in their willingness to develop. Spacecraft are no longer available only to powerful, advanced nations. Niowadays, any university can build a functioning satellite. This however is not true for rockets. One does need a fair-sized rocket to launch any decent-sized spacecraft (i.e., one with at least a few hundreds of kg of mass) into low Earth orbit - the minimum requirement for useful applications such as space based Earth observation, atmospheric science, prospecting or telecommunications.

However, there is no lack of launch service providers for moderate payloads into the low Earth orbit. Many former ballistic missiles have been converted to commercial launch vehicles, thus effectively turning swords into plowshares. And then there is quite a number of newly developed rockets on the market. So if you want to launch any payload of between, say several hundreds of kilograms and two tons into any orbit between low Earth and geostationary, you will have lots of choice.

Any nation that is sincerely interested in using space to further its development does not need to build its own rocket; they can find a launch service provider. Some providers may be politically unacceptable, no sweat, there are plenty of competitors.

So if a nation sets out to design their own rocket without even having a space program (such as North Korea or Iran), this nation isn't going about it the right way. In such cases, one should question their motivation: They might in fact be developing a ballistic missile (which indeed is not so easy to obtain commercially) under the guise of a civilian rocket program or pulling off some other political stunt. Dictatorships like doing such things that really don't do anything at all to advance their nation.

Nigeria definitely is not of this ilk. The Nigerian government appears to be serious about acquiring national expertise in key technologies through international collaboration. The logical sequence is:

learn how to use satellites,
learn how to build and use satellites,
learn how to build, launch and use satellites.

Nigeria's space policy is adhering to this logical sequence, and that's a good thing.

In 1999, in the wave of change that swept the country following the end of the military rule, the National Space Research and Development Agency NASRDA was created. The first NASRDA satellite, the Earth observation satellite NigeriaSat-1, was built in Great Britain by SSTL, a company specializing in small satellite platforms. Nigeriasat-1 was launched in 2003 on a Russian Cosmos rocket. A micro-satellite with a launch mass of 140 kg, it is part of a multi-satellite constellation especially for disaster relief support. Other satellites in the Disaster Monitoring Constellation (DMC) are being operated by Great Britain, Algeria, Turkey, China and Vietnam. A program can hardly be more useful, beneficial, international and cooperative than that.

This made Nigeria the second sub-Saharan country after South Africa to own a satellite. Procurement and development evolved in parallel with the training of personnel that would operate the spacecraft from the Nigerian space control centre in the nation's capital, Abuja. These experts constitute the core of the expanding Nigerian space competence.

Inevitably, there are those who claim that Nigeria didn't get its priorities right. I think that such criticism is parochial and blinkered. But it is also a remarkable sign of progress that governmental decisions can be openly discussed and criticized. Still, some of the criticism is clearly unfair and uninfomed - a sign that those who voiced the criticism may have harbored unrealistic expectations about what can reasonably be expected of a tiny Earth observation satellite. Some criticized that a bad plane crash hand not been observed by the satellite (well, doh, if the satellite wasn't over Nigeria at the time?). Others bickered that no warning was issued beforehand in those events when locals tried to steal petroleum from a pipeline and caused a fires (ditto ... and furthermore, one should not over-estimate the image resolution achievable with small space-based optics).

2007 saw the launch of the first Nigerian geostationary communications satellite, NigComSat-1, built and launched in China. This failed in 2008 - quite a setback, also in financial terms, as the failure left the operator Nigerian Communications Satellite without a space segment and with no transponder capacity to offer on the market. Luckily for Nigeria the warranty had not run out when the satellite failed. A replacement satellite will be built and launched for free, though not before 2011.

The next Earth observation satellite, NigeriaSat-2, will again be built by SSTL. Launch is foreseen for late 2010 from a Russian base. Still a small satellite, this will be significantly more powerful than its "little brother". Space-based Earth observation and telecommunications are precisely the kind of applications a large, not widely developed country needs. The earthquake disaster relief effort in Haiti demonstrated how indispensable up-to-date satellite imagery is in such situations. This imagery is just as indispensable in everyday use for development, wilderness management and environmental protection.

NigeriaSat-1 images of the 2005 New Orleans flood by hurricane Katrina, Source: DMC International Imaging

Lately, reports on more ambitious projects have surfaced. There has been talk about the first Nigerian astronaut (Why not, all they have to do is to pay the Russians to train a candidate and offer him a seat in a Soyuz spaceship, like South Korea did) and of nationally designed and built satellites, which would be the second step of the logical sequence of events and should be within the capabilities of NASRDA.

Then, a Nigerian launch vehicle has been mentioned. Some press articles stated that it would be used to launch geostationary satellites. I find that rather unlikely. Firstly, geostationary satellites are no longer the growth market they once used to be. What would be the point of trying to compete with the numerous providers that already saturate this segment? Secondly, despite its location near the equator, Nigeria is not a suitable location for launches into the geostationary transfer orbit. To do that, you have to launch due East. From Nigeria, the rocket would have to cross half the continent and numerous populated areas. Not a good idea. It is much better and a lot more sensible to envisage launches to sun-synchronous Earth observation orbits. Then you have to launch into a direction of around 190 deg, i.e., just a tad to the West of due South. Nothing but the South Atlantic there, and then the Antarctic, and coming up on the other side, the Pacific - no risk of hitting inhabitant regions.

I am sure there still is lots of scope for improvement in Nigeria. But some things are going right and there is no point in just harping on the bad and not mentioning the good. We just have to remember where that nation was 10 years ago and what they have achieved since then. Any nation as large as Nigeria has no alternative to embracing technological advance. It will have to develop or it will collapse under its population growth. If Nigeria succeeds in becoming an emerging nation, it will eventually become an economic powerhouse that will advance all of West Africa. If Nigeria fails ... well, I don't even want to consider that possibility. It doesn't bear thinking about. At any rate, it was a wise and perspicacious move to approach space technology in this fashion. A nation that does not have the means to harness space technology will not be able to develop. It's that simple.

I for one wish Nigeria success. OK, so the Super Eagles' performance at the 2010 World Cup wasn't exactly stellar. Better luck 2014 in Brazil - it will be interesting to see how Nigeria will have advanced until then.

The above article was originally written in German and published on kosmologs.de as a contribution to a series of 32 articles that highlighted selected aspects of the scientific and technological environment of each of the nations competing in the 2010 World Cup in South Africa.

Tomorrow: Japanese Asteroid Probe Hayabusa Limps Home

+++ Update: The entry capsule has landed and shall be retrieved in the course of Monday. The Hayabusa craft dis-integrated in the atmosphere. More here, with pix +++

Talk about a chaotic mission. What could go wrong did go wrong, except for that final crippling damage that would have terminated the mission for good. But I bet nobody would have thought Hayabusa would make it.

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Nobody, that is, except the spacecraft control team in the control centre in Sagamihara, not far from Tokyo. Somehow they managed to solve an endless stream of problems and coax a moribund spacecraft back from the brink, time and again, and they made it perform the manoeuvres required to return to the Earth.

Hayabusa (隼 in Japanese, or, written in Hiragana: はやぶさ), is the Japanese word for "peregrine falcon". Up to launch, it was also known as MUSES-C. The mission concept was quite straightforward: Fly to an Earth orbit crossing asteroid called 25143/Itokawa, after Hideo Itokawa (糸川英夫), the father of the Japanese space programs, pick up some samples and bring them back to Earth.

Hayabusa was launched on May 9, 2003 with a Japanese Mu-V rocket from Kagoshima spaceport in Southern Japan. Although the probe's launch mass was only 510 kg, the rocket couldn't manage insertion into an escape trajectory. Instead, the launch orbit was a wide ellipse, and the spacecraft had to use its four ion engines to leave the Earth. Ion thrusters deliver a very small thrust but are very fuel-efficient. More than two years and one Earth swingby manoeuvre later, the spacecraft arrived at the asteroid in September 2005.

By then, it had already taken some hits. The October 2003 solar eruption, one of the most violent ever registered, had degraded its solar arrays. That was bad because the ion drive depends on electric power, and reduced power means lesser thrust or increased propellant consumption - or both. But there was still enough power to reach the asteroid.

Two out of the three momentum wheels also ceased functioning. These are used to control the attitude, the spacecraft's orientation in space. Without wheels, every attitude change consumes propellant.

Once Hayabusa started orbiting the asteroid, things appeared to be looking up. The asteroid was mapped and photographed extensively. But then the situation went south. First, an attempt to deploy a tiny lander probe named MINERVA failed - inadvertently it was released when the spacecraft had just executed a thruster manoeuvre carrying it away from the asteroid rather than towards it. So MINERVA uselessly drifted off into space.

Sample extraction was supposed to be an operation of the slam-bam-thank-you-ma'am kind. Asteroid surface temperatures are extreme, so it's not a good idea to hang around more than absolutely necessary. According to the mision plan, the spacecraft was to alight and perch on a tubelike structure and fire a small tantalum bullet into the regolith. The impacting bullet would whip up some dust that would travel up the tube and settle in the probe container, and then the spacecraft was to lift off immediately.

But that's not how it turned out. The dress rehearsal failed badly. Although the spacecraft wasn't even supposed to land at that time, it hit the surface and radio contact to the Earth was interrupted. In the following hours, it appeared the mission was lost - but then, suddenly, a signal from Hayabusa was captured. The spacecraft had managed to take off after all!

Analysis of the telemetry data later showed that the spacecraft had spent 30 minutes on the surface and even come into close contact with the hot rocks and dust. Overheating apparently had led to some damage. A few days later, following a second, controlled landing attempt, the bipropellant system sprang a leak and subsequently losing all of its chemical propellant load.

Although the second landing was arguably more successful than the first, it remains unclear whether the sample extraction actually took place. In the weeks to come the spacecraft underwent a near-death experience resulting in amnesia, when parts of the onboard computer memory were erased. There are indications that the sample extraction mechanism may not have been triggered. But still, some surface dust may have ended up in the sample container - perhaps as much as one gram.

This definitely was the nadir of the entire venture. The bipropellant system: gone. Two of the momentum wheels: gone. This means that effectively the attitude control system was shot. The batteries were shorted and dead, most likely due to overheating. Two out of four ion thrusters were out of order, one appeared damaged and the only functioning one was the one with the highest number of operating hours, and therefore the highest likelihood of failure. When the chemical propellant vented, it caused a tumbling motion, so the high gain antenna no longer pointed towards the Earth and radio contact had been lost. The only positive thing was that the Xenon propellant tank for the ion drive was still intact. If that had gone too, it would have been curtains, then and there.

Spacecraft engineers don't give up easily. As winter turned to spring in 2006, and Earth moved back into the viewing direction of Hayabusa's high gain antenna, the control team managed to re-establish command access and stop the tumbling. This required venting some of the precious Xenon propellant through small cold gas thrusters that had been added as a wise precaution for contingencies. There was no alternative, but the Xenon was badly needed for the return trajectory, so the team took care not to vent a drop too much.

In the meantime, the return window had closed, but there was a second chance in April 2007, more than one and a half years after arrival at the asteroid. This would lead to an Earth encounter in June 2010, barring further disasters. Hayabusa gingerly set off, but everyone was aware that its chances were slim. Just one more breakdown, and it would be over. But then, for a change, there was a lucky break! They managed to re-start one of the two defective ion thrusters. That was very fortunate, because soon afterwards, one of the other thrusters, the one that had been half-working, failed.

Animation of asteroid 25143/Itokawa, based on the data model for its shape generated on the basis of the Hayabusa imagery and laser altimeter measurements. This model can be downloaded from the JAXA web site. In the middle of the bottom side the "Muses Sea" is visible (the name is a pun on the original mission name MUSES-C). This area is free of large rocks and therefore was chosen as landing site. The maximum extent of the asteroid is around 550 meters. Source: Timo Prange, Michael Khan, ESA

So Hayabusa limped on, and in due course, guess what: there was yet another failure: With one of the two remaining ion thrusters, the ion accelerator failed, and with the other, the neutralizer. However, one needs both accelerator and neutralizer to operate an ion drive. The engineers found a workaround: they programmed the onboard software to combine the working accelerator of one thrsuter with the working neutralizer of the other.

So on the spacecraft went, but now, soon, its fearful trip will be done. Tomorrow, Sunday, June 13, 2010 around 16:00 CEST (14:00 UTC), very conveniently located just between the end of one world cup match (Algeria vs. Slovenia) and the start of another (Serbia vs. Ghana), the 17 kg entry capsule with its (hopefully not empty) sample container will enter the Earth atmosphere. During the past weeks Hayabusa has successfully manoeuvred itself into a trajectory that enters the atmosphere such that the capsule, which is deployed only 3 hours prior to entry, will land in the Australian desert near Woomera.

Following the red-hot hypersonic phase the capsule will glide down to Earth under a parachute and plonk down softly in the sand. After recovery it will be airlifted to Japan and opened in a safe lab envioronment. If it is found to contain asteroid samples, this will have been the first sample return from the surface of any celestial body other than the Moon. A magnificent scientific and technological achievement and a true milestone of space research. But even if the sample return didn't work, this mission will enter the annals of spaceflight. The asteroid science phase is a great achievement in its own right.

And what about Hayabusa? After deploying the entry capsule it will no longer serve any function, and anyway, there is nothing one can do about it, so it will simply follow the entry capsule into the atmosphere and burn up ...

My heartfelt congratulations to all project team members. おめでとう御座います！

And now for some editorializing!

The team has done a fantastic job. No doubt about that. But still, some things need to be pointed out. Traditionally, the Japanese space effort has been handled by competing agencies. Earth observation, communications satellites, development of the large H-series rocket and manned spaceflight have been the responsibility of NASDA, headquartered in Tsukuba. Conversely, ISAS in Sagamihara, operated jointly by the famous Toudai (the University of Tokyo) and the education ministry Monbusho, operated astronomy, interplanetary and space science missions. While NASDA enjoyed a large budget allowing it to tackle ambitious ventures, ISAS was always forced to operate on a shoestring. NASDA, ISAS and another agency have now been merged, forming the the Japanese Aerospace Agency JAXA, but that move still doesn't address the underlying issue.

With space missions, as with all large technical projects, there is a minimum level of resources required to reach critical mass. If critical mass is not attained, the project is likely to experience a succession of defects and face a large risk of complete failure. This is axiomatic; it follows from the fact that one is forced to procure cheap (as opposed to good) components, the level of redundance is too low and one lacks the means to train people to do their jobs as well as they want to do them.

ISAS missions have been plagued by a history of crippling defects. Not just MUSES-C/Hayabusa, also PLANET-B/Nozomi (where the team did as good a job as Hayabusa's but ultimately just ran out of luck) and others. That's not because they don't have experienced, talented people there. I know people from ISAS. They're among the best in the world. The problem is that these projects didn't reach critical mass. Perhaps they were just a few millions short of a resounding mission success. If they'd had those missing resources, who knows? Hayabusa might have been running just as smoothly as shown in the youtube video below.

Further Information

Live webcast from the Hayabusa control room in Sagamihara

Press Kit for Hayabusa's return

Web site on Hayabusa's return on jaxa.or.jp

JAXA press release: "Capsule reentry plan", June 12, 2010

Hayabusa project web site on jaxa.or.jp

Archive of all press releases on Hayabusa

Web article by E. Lakdawalla from the Planetary Society

Article on spaceflightnow.com with timelines, details and links

Here is a really cool movie with great music, showing how smoothly the mission could have gone, had everything worked according to plans.

Scilogs post from March 9, 2010 on the maximum rotation rate of gravitationally bound asteroids

Asteroid Bonanza

Rhyolite, Nevada, April 1, 2010: Earlier this year a team of astronomers under John Sutter from the American Western Center for Minor body Observations of Nevada (AWCMON) in Rhyolite, Nevada found yet another Earth orbit crossing asteroid. Nobody took much notice; neither the asteroid's orbit or its size were remarkable. It was given the identification code 2010AU79 and that was that. Back to more important work - or so one thought.

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However, in February there was an opportunity for spectroscopic analysis. The results of this did make people stop and think. The first reaction was to disbelieve the data or their interpretation. But then, just a few weeks later, more data came in and confirmed the February findings. Finally, science had to face the fact that 2010 AU79 was anything but a run-of-the-mill asteroid.

A press conference was held today, Thursday, April 1, 2010 in the city hall of the thriving Nevada township of Rhyolite. There, the asteroid's discoverer Sutter declared that:

[...] The extremely high rotation rate of once every 7±0.3 seconds inferred from the light curve leads us to believe that this body must be a monolith.[...]

(Author's note: rubble pile asteroids held together by gravity cannot rotate rapidly; this would lead to large centrifugal forces and rip the body apart. In fact, the rotation of such bodies cannot be faster than once every 2.2 hours.)

Sutter went on:

[...] Having a 300 meter (author's note: 1000 ft) object like 2010 AU79 that is a fast-rotating monolith occasioned raised eyebrows, but no dropping jaws. [...] (Author's note: Spectroscopic) analysis showed that it must be a metallic body. Metallic, or M-class asteroids make up about 5% of the asteroid population (Author's note: = the total number of asteroids out there) and they are typically composed mainly of iron and nickel. However, 2010 AU79 is different; at least 10% of its mass must be ... gold.

All heavy elements including gold are formed in supernova explosions. The gas and dust clouds from which stars and planets form are known to contain gold, as do asteroids and comets - albeit in minute quantities. The fact that this particular asteroid contains such a high percentage of gold is extremely unusual.

Although Dr. Sutter made a great effort to downplay its significance, this announcement hit like a bombshell, and not just among scientists. The press conference ended in uproar, Rhyolite city hall had to be cleared by Nevada state troopers, and the scientists were discreetly led out through the back door. An unusual end of a scientific press conference, even by Nevadan standards.

This much is certain: The political and economic implications of this discovery are enormous. Even if only 10% of 2010 AU79 are made up of gold, this amounts to 20 million metric tons - over one hundred times more than all the gold ever mined on Earth!

Mining stock suffered dramatically in the wake of the announcement but then recovered when it was realized that there would be no way of mining the asteroid any time soon. The world's governments are still jittery, though. All major currencies are backed by national gold reserves. If these suddenly became worthless, chaos would ensue.

Conversely, ufologists saw their stock soar. Imaginative theories sprouted like mushrooms: for these people, no natural process can account for such a mother lode in space; no explanation short of an alien artifact is acceptable.

I am very upbeat about the turn of events: Space agencies should send missions to 2010 AU79 and bring back a few kilograms of samples. Then not only would scientists find out for sure how this body came to be, the proceeds of the subsequent sale of the asteroid material should serve to finance the mission cost. Its exclusivity should ensure that the price per ounce of asteroid gold remains a multiple of that of an ounce of gold mined on Earth, and if they bring back only a few kilograms every time, the market will not collapse.

So here, finally, we have a business case for self-financing space research, at least for the coming decades. Of course, if the quantities of mined asteroid gold do rise dramatically, the business model will have to adapt - but that will not happen in the immediate future.

Usually well-informed sources in Washington DC have picked up as yet unconfirmed rumors that the White House is considering a reversal of its February decision to ditch the Constellation program that would allow manned exploration of near-Earth asteroids. It is not known whether these rumors are related to the 2010 AU79 announcement.

One thing is for sure: The world is in for a change. 2010 AU79 will turn out to be a watershed not only in the way things are run on Earth, but also in the way we explore space. April 1, 2010 may well be remembered as the day when spaceflight started for real.

Appeal Against LHC Nixed by Constitutional Court

The German constitutional court, the highest court in the Federal Republic of Germany, on March 9, 2010 refused to accept an appeal filed by a German woman living in Zürich, Switzerland, for an injunction forcing the German government to take action to limit operation of CERN's Large Hadron Collider (LHC).

(Lesen Sie diesen Artikel hier auf Deutsch)

This does not appear to have been widely reported outside of Germany, which I find surprising. After all, Germany is not only a founding member of CERN, but also its largest single contributor of funds, with almost 20% of CERN's budget. Had the injunction been imposed as sought by the plaintiff, this would likely have posed a significant impediment to the operation of the LHC. So the ruling is good news for science.

Reasons for the ruling are listed on the web site of the German Constitutional Court (in German).

Here is the salient paragraph, in German:

[...] Zur schlüssigen Darlegung möglicher Schadensereignisse, die eine Reaktion staatlicher Stellen erzwingen könnten, genügt es insbesondere nicht, Warnungen auf ein generelles Misstrauen gegenüber physikalischen Gesetzen, also gegenüber theoretischen Aussagen der modernen Naturwissenschaft zu stützen [...]. Praktisch vernünftige Zweifel setzen - wenigstens - die Auseinandersetzung mit Gegenbeispielen, also Widerlegungsversuchen der jeweiligen Aussagen voraus. Namentlich im Bereich der theoretisch weit fortgeschrittenen Naturwissenschaften erfordern vernünftige Zweifel zudem ein hinreichendes fachliches Argumentationsniveau. Die schlüssige Darlegung einer Warnung kann jedenfalls nicht auf solche Hilfserwägungen abstellen, die ihrerseits mit dem bewährten, anerkannten Hintergrundwissen des jeweiligen Faches in Widerspruch stehen. Die Beschwerdeführerin unterschreitet diese Anforderung, soweit sie neben einem Theorem, auf welches es für die Sicherheit des LHC nicht ankommt, diverse Hilfserwägungen („Atto-Quasar“, „Superfluidität“) vorträgt, von denen die „Weltgefahr“ zwar ausgehen könnte, die aber - jedenfalls was diese Ergänzungen angeht - nach ihrem eigenen Vortrag bislang weder wissenschaftlich publiziert noch auch nur in Umrissenen theoretisch ausgearbeitet sind.

I won't even try to translate this from German legalese to English legalese because I know that my translation would not do it justice. Also, legalese gives me a headache. What I can do is to give you just the gist:

If you want to voice your concern, and especially if you expect the government to take action, you have to do better than merely couch your concern in terms of general mistrust against physics. You need expertise, you need to understand the theories that you are trying to refute sufficiently well and you need to formulate salient counter-examples, all the more so if the theories you are up against are well-established, mature, have a solid theoretical foundation and are generally accepted among scientists in the field. If you have nothing more to offer than irrelevant side issues and vague pseudo-theories that are not even consistent with fundamental precepts of physics and are not based on solid, extensively published theory, then that just isn't good enough.

And if you want just the gist of the gist, here goes:

If you have no idea what you're talking about, then shut up and don't waste everybody's time with drivel.

Further Information

CERN web site

LHC information on CERN web site

Simple Math: How Fast Can an Asteroid Rotate?

There are many really great things about astronomy. One is that one can get quite far just with elementary physics and basic math.

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Take asteroids, for example. "How fast can an asteroid rotate without being ripped apart?" - answering that needs a lot of high-powered math, right?

Wrong. It's really trivial.

OK, OK, I have to modify that statement. It's trivial if we can make some assumptions: (1) the asteroid must be of the rubble pile type, i.e., a pile of rock held together by mutual gravitational attraction, as opposed to a massive monolith and (2) the density distribution inside the asteroid should be more or less homogeneous. But those assumptions apply to the overwhelming majority of asteroids, so it's OK to make them.

The underlying physics is quite straightforward: rotation creates a centrifugal force. The faster something rotates, the larger the centrifugal force. If we assume the rubble pile model, the asteroid is composed of a heap of rocks of various shapes and sizes. These have mass, so they exert gravity. Each rock attracts the others, so they end up nestling against one another, with some gaps in between. If the centrifugal force, which tends to pull the rocks outwards, away from the centre of mass, exceeds gravity, which acts towards the centre of mass and holds the rubble pile together, the asteroid will be ripped apart. If the centrifugal force does not exceed gravity, the asteroid will not be ripped apart.

In between, there must be a rotation speed where the centrifugal force is exactly equal to gravity. This corresponds to the maximum rotation rate that we are looking for. It's that simple.

I'm not going to attempt to write the entire calculation in html. Was it Stephen Hawking who said that every equation reduces the potential reader base by half? I'm going to need seven equations, so I'd lose over 99% of my readers, and obviously, I don't want that. So I resorted to a trick. The equations are still there, but I put them in a separate document here.

The results were amazing, also to me. In the end, the limiting rotation period depends only on the density. I get a shortest possible period P of 375780 divided by the square root of the density in kilograms per cubic meter. If you hear a hissing sound now, don't worry, it's just physicists who are hyperventilating when they see my cavalier treatment of the units without which, let me hasten to add, no meaningful calculation are possible. Please relax, dear physicists. I'll be really rigorous next time. I promise.

Anyway. We get this very simple formula that shows that the minimum rotation period is a function of the asteroid's density. That's all there is to it, provided they're not monoliths. It doesn't matter whether the asteroid is large or small.

2000 kilograms per cubic meter is a good guess. Then the minimum rotation period is 8403 seconds or 2.33 hours. An asteroid that that takes a longer time to rotate will maintain gravitational cohesion.

None of this is new. If even I could compute this, many others could, and did. But I like it, because it's such a simple, elegant computation, and it turns out to be very consistent with observations. Asteroids are normally somewhat irregular bodies, so when you observe them, there will be a ripple in their apparent brightness. This is what is called the "light curve". The period of the light curve is the asteroid's rotation period.

Until lately hardly any asteroids with periods of less than around 2.2 hours were known. Most rotate a lot more slowly than that. Only recently have a few fast rotators been discovered; all of these are very small. This gives rise to the conjecture that the overwhelming majority of asteroids must be held together by gravitation. They can be rubble piles or ex-monoliths that have been fissured by an impact.

No large, fast-rotating asteroids have been observed. This does not constitute proof that there are no large monoliths, but even so, it can be seen as a strong indication. All known monoliths (or metallic bodies) - fast rotators with periods as low as several minutes - are small. That's why they weren't detected earlier.

These fast rotators must be interesting bodies. No pebble, not even a speck of dust could remain on them, and of course, no spacecraft could land there, it would just be swept away by the massive centrifugal forces.

Such bodies likely constitute the remnants of impacts between asteroids that led to their mutual destruction. A fascinating idea ... and all of that follows from one simple mathematical equation.

Not bad, huh?

Further Information

Planetary Database - Small Bodies Node

Harris: The Rotation Rates of Very Small Asteroids: Evidence for Rubble Pile Structure (LPI, 1996): A statistical analysis of the rotation rates of small asteroids known until the, lending support to the conjecture of rubble pile composition due to the absence of rotation rates that would require tensile rather than gravitational cohesion (i.e., a monolithic asteroid). Although many more small asteroids have been detected since then, Harris' observations still hold. Fast rotators are few in numbers and all of these are small.

Harris, Wisnewski: paper on asteroid rotation rates

Donnison, Wiper: Statistical analysis of asteroid rotation data (MNRAS 1999)

Fujiwara, Kawaguchi, Yeomans et al.: The Rubble-Pile Asteroid Itokawa as Observed by Hayabusa (Science, 2006):This paper summnarizes what was learned through the Japanese sample return mission Hayabusa to asteroid 25143/Itokawa, including conjecture that Itokawa was created by collisional break-up of a parent body and re-agglomeration of debris

Scheeres, Hartzell, Sánchez: Scaling Forces to Asteroid Surfaces: The Role of Cohesion (ArXiv, 2010): This paper looks specifically at very small, gfast rotating asteroids, suggesting that for small bodies, Van der Waals Forces maybe dominant and thus allow a degree of cohesion suprior to that explained by gravitational cohesion

Vernazza, Binzel et al.: Solar wind as the Origin of Rapid Redding of Asteroid Surfaces (Nature 2009):This paper analyzes the time scale for solar-wind induced weathering of silicate-rich asteroid regolith and the associated reddening, stating a figure of 1 million years for this process. From the observation that many near-Earth asteroids lack this reddening, suggesting recent action of a mechanism of surface re-shaping, it is conjectured that this must be due to gravitational perturbations during near-Earth flybys

Levasseur-Regourd, Hadamcik, Lasue: Interior Structure and Surface Properties of NEOs: What is Known and what Should be Unterstood to Mitigate Potential Impacts (Advances in Space Research, 2005): A comprehensive compilation of data on NEO properties and a summary of what can be derived regarding their interior composition, cohesion and porosity

"No Bucks, No Buck Rogers"

Today may mark the imminent end of US ambitions to lead space exploration. The "Vision for Space Exploration" (VSE) that former president Bush initiatied (however, neglecting to provide appropriate funding) may be axed.

(Lesen Sie diesen Artikel hier auf Deutsch)

If this proposal goes through, it may limit the US human space exploration to low Earth orbit for a long time. Not a very attractive option, especially in view of the more than $9 bn that already have been invested into the development of the Ares I and Ares V heavy launchers and the Altair moon landing craft, which may now well be eliminated from the Constellation project.

Here is an interview with spaceflightnow's Miles O'Brien with Lockheed Martin's John Karas on the future of the VSE. LockMart is prime contractor for the Crew Exploration Vehicle Orion that, if also axed, will not leave much of Constellation, nor of American manned spaceflight leadership.

Further Information

spaceflightnow.com web site

"This Week in Space" on youtube with this and other interviews und information

Article "White House Confirms Course Change for NASA" on space.com

Close Asteroid Encounter Tomorrow

Tomorrow, Wednesday, January 13, 2010, a small asteroid called 2010 AL 30 (presumed diameter 10-15 meters) will buzz the Earth at just 1/3 of the lunar distance. The point of closest approach will be passed around 13:00 UTC (14:00 CET). +++ Please also note the update at the bottom of this post. +++

(Lesen Sie diesen Artikel hier auf Deutsch)

This announcement in the Minor Planet Electronic Circular lists a set of observations that were used for orbit determination. They start on January 10, 2010 - that's how short a warning we get with these little fellas.

At first sight the asteroid's orbital period appears remarkable: It's almost exactly one year, just a bit more. The orbit is inclined by around 4 degrees with respect to the ecliptic, and it's quite eccentric. The aphelion is larger than 1.3 AU, the perihelion less than 0.7 AU.

The orbital period led to speculation that the object might be man-made, in analogy to the object J002E3, which probably is a spent Saturn V stage from the Apollo missions that barely managed to escape into a heliocentric orbit and then was temporarily re-captured into an orbit around the Earth in 2002.

For various reasons, this scenario does not apply here. The 1-year orbital period probably is no more than a fluke.

Where does this thing come from?

Probably 2010 AL30 is of natural origin. However, the possibility that it is man-made cannot be completely excluded. If so, it might be the upper stage of a rocket used in an earlier planetary mission, possible to Venus. The current orbit would have been acquired through a Venus swingby and other orbital perturbations.

The perihelion radius is somewhat suspicious. It's almost identical with the orbital radius of Venus, as this diagram shows. I produced this based on the orbit determination results given in the MPEC for Jan. 4, 2010. I numerically propagated the given orbital state backwards in time, taking into account the gravitational attraction of all planets and the Sun. As can be seen, the asteroid orbit intersects the Venus orbit in two locations close to its perihelion (well, almost, because there also is a difference in inclination).

In such a scenario, it's very likely that at some point in time the object must get close to Venus and undergo some more or less significant orbital perturbations. My numerical simulation also showed that this was the case. But then, of course, the initial orbit determination uncertainties will tend to multiply in the propagation, especially if there are close planetary encounters. This is rocket science .... but still, I have to live with the inaccuracies in the data available.

When plotting the obtained distances from Earth and Venus over time, as in the diagram to the left (Note: logarithmic y-scale), you can see that there was a close Earth encounter almost exactly 1 year ago, on January 12, 2009. This makes sense: If the period is 1 year, and we have an encounter on January 13, 2010, then logically there must have been one also one year earlier. There are no Venus encounters or anything else that might have changed the orbit in 2009.

Then, it looks as if there was a close Venus encounter in spring 2006, preceded by an Earth encounter in late 2005. Again applying all due caution and pointing out the uncertainties, these results do not appear to be altogether inconsistent with the conjecture that we have here the Fregat upper stage of the Soyuz launch vehicle that launched the ESA spacecraft Venus Express on November 9, 2005, with Venus arrival on April 11, 2006.

There are indications that the object may be rotating quite fast, which also would not be surprising in the case of a spent upper stage. If this is in fact a Fregat, then it is clad in reflective metallized foil for thermal reasons, so its albedo would be a lot higher than that of a natural body. Despite the Fregat's smaller size, distinctly less than the 10-15 meters tentatively assumed for this body, the reflective material would make it appear bright.

I assume that the hypothesis I am putting on the table here will be easy to disprove or to confirm once we have more observations and also some spectroscopy and radar, which hopefully will be the case by tomorrow.

An Afterthought: Coincidences Galore ....

I just couldn't let it rest, so I decided to approach the problem from a different tack. Let's assume that 2010 AL30 is the Fregat upper stage from the Soyuz launcher used for Venus Express. Then I need to find out whether the gravitational perturbation of the stage during its close encounter with Venus could have led to the orbital parameters we see now. The answer to this analysis was clearer than I had expected.

The hyperbolic arrival velocity at Venus amounted to around 4.6 km/s, the date and time and the direction are known. I used this data to compute the post-encounter heliocentric orbital elements for a large set of sample points in the B-plane. The B-plane is a commonly used tool for mission analysis, it constitutes an imaginary plane that is centered in the target planet (here Venus) and is perpendicular to the hyperbolic arrival velocity vector.

The results are plotted in the attached diagrams. The white circle in the middle is the impact zone. If you try to target a flyby within this zone, the pericentre radius is too small, so the craft (a space probe or a spent stage) would enter the atmosphere and burn up.

The first diagram shows that a post-encounter orbit with a semi-major axis of 1 AU (and therefore a period of 1 year) is easy to reach. The B-plane target parameters must then be on the dotted white line.

The second diagram shows the achieved post-encounter perihelion. No problem with around 0.7 AU.

Finally, the aphelion radius, shown in the third diagram. The orbit of object 2010 AL30 has an aphelion of just over 1.3 AU. No problem there, as the dotted white line shows. And here's what's strange: For the B-plane target area delimited by the little red circle in all three plots, you get exactly the combination of all three: a period of 1 year, a perihelion of just under 0.7 AU and an aphelion of 1.3 AU.

And there is more: This marked zone happens to be exactly the zone that you would target at if a Venus orbit insertion over the planet's north pole is wanted (It appears to be on the bottom side in the graphs, but that is just due to the way the B-plane axes are defined. Anyway, astronomers are used to seeing things represented upside down). Incidentally: Venus Express was targeted for orbit insertion over the north pole.

So, let's summarize briefly:

Numerical backwards propagation of the orbital state of object 2010 AL30, as determined in January 2010, turns out to appear to lead to a close Venus encounter in spring 2006 and an Earth encounter in late 2005. These epochs are consistent with the Venus arrival and Earth launch dates, respectively, of ESA's Venus Express probe.

From the known approach conditions of Venus Express to Venus one can derive that a target point close above the planet's north pole, as was chosen in that mission, would lead to a deflection of an inert body on the same trajectory, such as the spent Fregat stage, that has a period of 1 year with perihelion and aphelion distances of 0.7 and 1.3 AU, respectively. These orbital parameters closely coincide with those of object 2010 AL30.

Obviously this does not constitute proof. But I would say that we have a surprisingly long chain of unusual coincidences here. Wouldn't you agree?

Update

It is now Thursday, January 14, 2010. Object 2010 AL30 has come and gone. Improved orbit determination results are now available. The backwards propagation I performed on January 12 was based on the "old" set of orbital data. In fact, though there is some change in the orbital parameters, this change is a lot smaller than I expected, in view of the relatively short arc spanned by optical observations.

As you can see from the description of part of my analysis above, where I propagated the orbit backwards from the date for which the January 12, 2010 orbit determination was provided, I obtained a Venus encounter in early spring 2006. Date and distance were not entirely consistent with the Venus Express case, but close enough to warrant a closer look, and I expected that the uncertainties in the orbit determinaton, together with a magnification effect of the 2009 Earth encounter, would lead to some change here, moving the encounter date to April 11 and reducing the encounter distance.

However, as the post-encounter orbit determination does not differ significantly from the pre-encounter ones, there is no alternative but to conclude that 2010 AL30 in fact did pass no closer than 0.011 AU to Venus in 2006 and that this happened on February 25, some 6 weeks prior to the Venus Express arrival (see the updated distance plot). This is not consistent with the conjecture that 2010 AL30 might be the Fregat upper stage.

What does this mean? As stated earlier, probably 2010 AL30 is of natural origin. This hasn't changed. Even though the initial conjecture that the timeline of planetary encounters of object 2010 AL30 might indicate that it is the upper stage of the rocket that launched the Venus Express spacecraft did not survive the ongoing process of orbit determination - well, that's the way science works, in the end it's the data that counts - my other set of calculations also holds.

Anyone with a computer and some experience with celestial mechanics can check my results: if you send a spacecraft to a planet, it is not unlikely that the expended upper stage will pass close to the target planet and be deflected into an orbit that differs significantly from the original one. There is no reason to assume that man-made objects, even uncontrolled ones such as spent rocket stages, can only encounter the Earth with a relative velocity and direction that are akin to those it was launched to.

And to clarify another piont that was frequently made in reference to the 2010 AL30 issue: There is considerable confusion related to the significance of the fact that the orbital period amounts to almost exactly 1 year. This point is only of relevance if the object in question escaped the Earth at a very low velocity and remained in an orbit very similar to that of the Earth (either a "leading" or a "trailing" orbit.). On such an orbit there is no chance of meeting another massive body, so the object's orbit around the sun will not change significantly, and there is a high probability it will come back to the Earth, again at low relative velocity. But for rocket stages from interplanetary missions, this does not apply. These very likely did enconter a massive body along the way and one should not assume that their orbit must have remained essentially unchanged or that their period is close to one year.

The Low Down on Methane on Mars

From November 25-27, 2009, I attended a workshop on the topic of "Methane in the Mars Atmosphere", held at the site of the European Space Research Institute ESRIN in Frascati, Italy. This is my summary of what went on there and what I learnt.

(Lesen Sie diesen Artikel hier auf Deutsch)

First of all, I have to tell you that I am not a scientist. I am a spacecraft engineer and a mission analyst, and I have worked on more space missions than I care to remember. A major portion of these were missions to Mars. Not all of these missions actually happened - it's normal in the space research business to study dozens of missions, out of which, if you're lucky, two may proceed any further than the initial planning stage. That's the way it goes, like it or not. I do know a fair bit about the science, though obviously not nearly as much as someone who is active in the science proper. But perhaps my knowledge makes up in breadth at least partly what it lacks in depth.

I also have a German blog, and mostly, my English articles are more or less close translations of the original German ones. Not this one, though, because I wrote the German account of the workshop as a kind of diary, during the conference breaks. The present English article however is more like a digest of the salient facts, or rather, my interpretation of them. Feel free to point out any errors to me, I will gladly correct them.

So, what's it all about then?

The title says it all. The issue is methane on Mars, or more precisely: methane in the Martian atmosphere, because it because it hasn't yet been found anywhere else than in the atmosphere. In fact, so far, no organic matter (i.e., no carbohydrates) have been found in the Mars surface or subsurface. The existence of gaseous methane in the Mars atmosphere has been proven by three different sources. It's been measured independently and repeatedly by spectroscopes attached to terrestrial telescopes and Mars-orbiting spacecraft.The average abundance in the atmosphere can be in the low tens of parts per billion (ppb).

Since 2004, several papers have been published on the topic. In 2004, this one by Formisano et al. on observations of methane by an instrument called the Planetary Fourier Spectrometer (PFS) riding on the European Space Agency (ESA) Mars orbiter Mars Express created a stir. So did the latest one by Michael Mumma et al. on a plume of methane observed with a spectroscope peering through a terrestrial telescope over specific locations for a few months before it subsided. Both Dr. Formisano and Dr. Mumma and their collaborators were present and gave presentations at the workshop.

So there's methane on Mars, and so what? There's plenty of it in the Earth atmosphere, so why should we get excited if it's found on Mars? Well, that's precisely why we should get excited. 90% of the methane present in the Earth atmosphere is there due to biotic processes, i.e., because there is life on Earth and living organisms are releasing methane. We might in fact be seeing a sign of alien life here. If so, it would be the most significant scientific finding ever. Good reason to get excited. Very excited. But precisely because of the enormous implications, it is imperative be be extra-careful and explore all possible alternative explanations.

Where does the methane come from?

Methane, once released, has a limited lifetime. Ultraviolet radiation, which on Mars is not filtered by an ozone layer, would completely destroy (photochemically dissociate, for those who like big words) it in just 300 - 600 years. So there must be a source that replenishes it. There aren't all that many processes that could plausibly explain what scientists have been observing. Comets contain methane, among lots of other things. So a large comet impact a few decades ago might be the source?

Well, no, because observations show that the abundance of methane varies considerably with time over spans of just a few months. In fact, what is observed is most accurately described as plumes: Methane appears to emanate from limited regions and then is dispersed over wide areas by winds before subsiding. The Mars year lasts 687 Earth days, not quite two Earth years, and Mars has seasons because its equator is tilted with respect to its orbit, as is Earth's. There seems to be more methane around in northern spring and summer; it then disappears in Northern autumn and winter, though then it is spring and summer on the Southern hemisphere. So we're talking about a cycle here, and one that spans a few months, not hundreds of years. The observed cycle appears to be related to seasons (and thus to correlate with sunlight or temperatures?) and one might also be tempted to conjecture that it is more likely to be released on the northern hemisphere. But comets that periodically hit in Northern spring and summer? Nah. That just doesn't sound right.

This topographic map (Click to enlarge) shows regions where Mumma et al detected large methane plumes. According to Mumma et al., an increased abundance of methane correlates with a geologically ancient surface below, though not everyone agreed with this statement

Then there is a geological process called serpentinization. This refers to a series of chemical reactions, starting out with volcanic minerals, olivine or pyroxene being subjected to liquid water - lots of it - and creating another mineral, serpentine, along the way, and also methane. There we have a problem already, as liquid water cannot exist on or near the Martian surface. The atmospheric pressure is less than 1% of the Earth's. Liquid water would evaporate, ice would sublimate. Deep below the surface, water can exist in the liquid state, so if the process of serpentinization takes place, it has to be due to a significant subsurface reservoir of water. This has not been found so far, although two spacecraft are looking for it with a radar that can penetrate the ground, in one case up to a depth of several kilometers: ESA's Mars Express with its MARSIS and NASA/JPL's MRO with its SHARAD. But the fact that it hasn't been found yet doesn't mean it's not there.

A variant of the serpentinization theory is that this took place very long ago and that resulted in extended subsurface reservoirs of methane, from which some portions are periodically released. There is abundant evidence that large quantities of liquid water once existed on the Mars surface, when the planet was young, warm, volcanically active and clad in a much denser atmosphere than the tenuous wisp of today. As volcanism ceased and the planet cooled and froze, so did that water. Water ice is still plentiful, and sporadic volcanism seems to have existed until fairly recent times, which might have melted some of the ice at least for limited periods. All the ingredients for serpentinization were there, so if this is the source of atmospheric methane, we should look for the reservoirs and the vents.

The reservoirs could be in the form of clathrates: methane molecules trapped in "cages" inside ice crystals. One of the presenters addressed this issue, which by the way also is of relevance for the Earth. Some theorists have conjectured horror scenarii involving massive releases of methane from submarine clathrates. Such theories appear to ignore the fact the methane release is an endothermic and therefore self-limiting process, releasing part of the methane also lowers the ice temperature and thus inhibits the release of further gas. Apart from the implications for terrestrial doomsday scenarii, this effect seems to indicate that clathrates might not be a plausible type of reservoir that would support short-term release of a massive plume of methane.

The case for life

And then of course, there is the possibility that methane might be generated by life. If life does exist on Mars, it is unlikely that one could expect anything more than primitive microorganisms. On Earth, we know Archaea, a class of ~~very primitive microbes~~ microorganisms that do not even contain ~~cell membranes~~ a cell nucleus. Some of these are anaerobic methanogens, meaning that they thrive on the absence of oxygen (they would even be killed by the presence of free oxygen) and their metabolism produces methane.

Conditions on Mars are not exactly benign. Ultraviolet radiation, as mentioned, likely sterilizes the upper few millimeters of ground. On top of that, as Mars is not protected by a magnetic field nor a dense atmosphere, cosmic radiation, mostly charged particles from the Sun but also much heavier and faster particles from elsewhere in the galaxy, sleets through the ground up to several meters of depth. This bombardment, which goes on continuously, day after day, aeon, after aeon, easily packs enough punch to break up complex molecules which are a prerequisite for life.

And then there are aggressive oxidants, mostly hydrogen peroxide, which is triboelectrically created through strong electrostatic charges induced by the frequent massive dust storms that engulf large portions of the planet. Oxidants could oxidize (burn) carbohydrates and thus break them up, ultimately, to carbon dioxide and water. In fact, that's why we use hydrogen peroxide as a disinfectant, because it efficiently kills germs.

Not a situation that sounds conducive to life. On the other hand, lately more and more extremophile biots have been found on Earth - life forms that live and thrive near submarine volcanic vents, deep down in rocks, in enclosed Antarctic lakes, in crude oil reservoirs, even inside the Chernobyl reactor, thriving on radiation. A geologist at the workshop presented findings from the Rio Tinto region in Spain, where methanogens were found to exist in very salty, acid water. Is it unthinkable that life originated on Mars, when it was still a more benign place, and now continues to exist somewhere below the surface, safe from the most harmful radiation and oxidants? It wouldn't even need a continuous supply of liquid water. A sporadic one might do. Terrestrial biots have shown their ability to survive amazing stretches of time, especially if they can form spores. But even higher life forms, even actual animals such as tardigrades have proven their skills as survival artists.

It is in fact possible to discern between a geological and biological origin of methane by studying the isotope ratios (deuterium vs. hydrogen, 13C vs. 12C, 18O vs. 16O). But this imposes added requirements on the measurement accuracy and probably will only be feasible with solar occultation measurements (more on those later) or with dedicated lab equipment on landed craft.

Where does the methane go?

As stated, the observed plumes disperse and the methane abundance decreases much faster than would be explained by photochemical dissociation. There must be another process, one that removes methane - tens of thousands of tons - in months, rather than hundreds of years. You mazy have heard of the Saturn moon Titan, which was shown to have an actual methane cycle similar to the water cycle on Earth. But on Titan, surface temperatures are around 90 K (-180 C), the pressure is 1.5 bar, close to the methane triple point. On Mars, conditions are nowhere close to that. Methane condensation is not an option. Water, carbon dioxide, those, yes, but methane, no. Likewise, chemical decomposition in the regolith or re-introduction of the methane to underground reservoirs were regarded, but experimental evidence suggests that this is not a plausible explanation either.

So what else? There appears to be some correlation between the abundances of water vapour and methane, though increased amounts of water vapour do not necessarily coincide with increased amounts of methane. So water may have to do with the release or generation of methane. But it could also have to do with the methane depletion, perhaps via intermediate products such as hydrogen peroxide and hydroxyl. Hydrogen peroxide alone could do it, as one presenter pointed out, the available quantities should be largely sufficient. But then, there should be methane decomposition products such as formaldehyde (which was claimed to have been observed in 2004, but that claim was never substantiated) and carbon monoxide, which is present, but in much lesser quantities than that methane decomposition process would suggest.

So we still have a problem here and much research is still needed. There clearly is hydrogen peroxide in the atmosphere, and the fact that the methane tends to disappear in southern spring and summer, which is the global dust storm season on Mars, promoting triboelectric hydrogen peroxide generation, also seems to be more than just a coincidence. There may be other agents involved, in particular, hydroxyl, which is known to be highly reactive and could accelerate the chemical decomposition to the observed levels.

Just how do they measure a few ppb, anyway?

That is a good question and it also explains why methane was not discovered earlier. On distant Titan, the dense atmosphere contains several percents of methane. That's a lot of methane, and that's fairly easy to measure. The much lower abundances on Earth are a different matter. In fact, several recent new technologies made these measurements possible.

In general, the chemical composition of a planetary atmosphere, down to the trace gas level, is measured via spectroscopy. This comes in different flavours. One is absorption spectroscopy using terrestrial telescopes. There, you observe the sunlight that shines on the Mars atmosphere and is reflected to your detector. If you analyze the spectrum of the received electromagnetic radiation (visible, infrared or ultraviolet light), some discrete frequencies will show decreased intensity. The frequencies are typical for given chemical elements and compounds. However, you have to watch out because certain frequencies might already not have been present in the spectrum of the light that shone on the planet, and other frequencies may be absorbed in the Earth atmosphere.

You have to take into account that the observed absorption bands will appear at frequencies that are different from their actual values because of Doppler shift: Earth and Mars are moving on their different orbits, and the Earth is rotating, and all of that adds up to significant relative velocities. That is in fact a good thing, because the same compounds you are trying to detect in the Mars atmosphere also exist on Earth, and the signal from the Earth atmosphere would completely blot out the minute radiation you receive from Mars. But thanks to the Doppler shift, the "signature" of the Mars atmosphere moves to different apparent frequencies, where there is no interference with terrestrial gases.

A way to avoid these difficulties is to get closer to the red planet. Then you can apply extinction spectroscopy. To do that, you have to observe the light from a known object, such as a star as it shines through the planetary atmosphere. Ideally, you observe sunlight as it traverse the Mars atmosphere, which is obviously not possible from the Earth, as Mars is farther from the Sun than we are. Ideally, the spectroscope is on a spacecraft orbiting Mars. In particular if sunlight is used, this form of spectroscopy will allow the precise measurement of even minute quantities of trace gases. If in orbit around Mars, you can also observe the thermal emission of the atmospheric gases and analyze this spectrum, if the appropriate hardware is installed on your spacecraft. This is referred to thermal emission spectroscopy.

So, what will come next?

The workshop also gave an overview on Mars missions looking for methane in the near future.

NASA'S MSL will be launched in the 2011 launch window. The landing site of this 800 kg monster still is to be decided; there are five possible options.

The 2013, NASA's aeronomy mission "Maven" will be launched. This is an orbiter that will be placed in an orbit with a pericentre altitude of only 150 km, so it will ~~grave~~ graze the upper atmosphere during each orbital revolution. The primary mission aim is to study the loss of atmospheric matter through interaction with the interplanetary medium.

The launch windows in 2016, 2018 and 2020 will see launches of joint ESA-NASA missions. In 2016, an ESA-led orbiter mission will be launched. This shall specifically study trace gas abundances via extinction measurements during occultation events, when the spacecraft enters or exits the planet's eclipse cone and therefore "sees" sunlight filtered by the atmosphere.

As stated, this type of measurement allows accurate detection of even the rarest trace gases, so will will finally find out about methane's decomposition products such as formaldehyde or methanol.

In 2018, a NASA-led mission will send two rovers to Mars. One will be provided by ESA, the other by NASA. The ESA rover's task will be to search for traces of extant or previous life. Both rovers will land at the same location and then pursue their separate mission goals. The fact that for the first time two rovers will be active that the same location is expected to ~~load~~ lead to considerable synergies. The orbiter that will have been launched in 2016 will serve as data relay.

Finally, in 2020, a network of landers will be placed on the Martian surface. The exact scientific aims yet remain to be defined, but they are likely to cover a wide range, including meteorology, soil chemistry and atmospheric research.

The low down

The most important thing I learnt during this conference was that, though it indubitably is interesting and important to find out what process releases methane into the Martian atmosphere with a local and seasonal variability, in the methane concentration on Mars, the really big question is how the methane is so rapidly removed from the atmosphere. There clearly is a very efficient process at work here, but science currently has no idea what that may be.

I think it is likely that we will find that both methane source and sink are not single, but rather combinations of different processes, as is the case on the Earth. It will be very interesting to find out how the competing processes interact, perhaps synergetically. And of course, there remains the biggest question of all: whether a biological process is involved.

Further Information

Workshop web site on the ESA web pages

Article on the workshop on the ESA Science web pages. The presentations held at the workshop are available through this page via hyperlinks in PDF format.

Web site of NASA/JPL's MSL rover mission

Michael J. Mumma, Geronimo L. Villanueva, Robert E. Novak, Tilak Hewagama, Boncho P. Bonev, Michael A. DiSanti, Avi M. Mandell, Michael D. Smith: Strong Release of Methane on Mars in Northern Summer 2003, Science 20 February 2009: Vol. 323. no. 5917, pp. 1041 - 1045

V. Formisano, S. Atreya, T. Encrenaz, N. Ignatiev, M. Giuranna: Detection of Methane in the Atmosphere of Mars, Science, 3 December 2004: Vol. 306. no. 5702, pp. 1758 - 1761

E. Chassefiere: Metastable Methane Clathrate Particles as a Source of Methane to the Martian Atmosphere, Icarus Volume 204, Issue 1, November 2009, Pages 137-144