Rosetta Launch Memories
from Gerhard Holtkamp, 13. November 2009, 21:20
Everybody in the space business hates launch delays. I experienced my fair share of delays (even as close as two seconds before liftoff). But in case of the Rosetta spacecraft launch delays played in my favour and let to some unforgettable memories...
The European spacecraft Rosetta just passed Earth on its final gravity assist maneuver enroute to a historic rendezvous with a comet. Go-For-Launch co-blogger Michael Khan has given a detailed description of this third flyby. For me it brought back memories of the launch which I had the privilege of witnessing on the spot.
Rosetta had been ready to depart in January 2003 to Comet 46P/Wirtanen when the month before an uprated Ariane 5 rocket experienced a failure. This caused the delay of all further Ariane launches to sort out the problem. As flights to rendezvous with comets require complex trajectories with very specific launch dates a new target needed to be selected.
Analysis showed that Comet 67P/Churyumov-Gerasimenko could be reached by Rosetta in its original configuration with a launch date of February/March 2004. This new date allowed me to get an invitation to watch the launch in Kourou thanks to a colleague of mine.
With launch slated at 4:37 local time on February 26th we had to get up at around 2 o'clock. There was some mild chaos in the hotel lobby where we were assigned to the busses which would bring us to the various observation sites. I ended up on a hill overlooking the whole space complex some 13 km from the actual launch site. (A neigbouring hill is open to the general public to follow launches without invitation. Information about visiting the Guiana Space Center in Kourou can be found here.) Other observation sites (by invitation only) are the very control room and a place a little over 5 km away from the launch complex.
Arriving about half an hour before the planned liftoff there was just enough time to spot a pair of tarantulas (better watch your step at these early hours in the morning) when we were told that the launch was off due to excessive wind speed. (The Ariane 5 could have launched under these conditions but if the wind blows from the wrong direction debris and toxic gasses might reach the nearby town in case of an accident.)
Another launch attempt was being made the next night but this time we only got as far as the hotel lobby where a note was put that the launch had been postponed again. A piece of insulation of the liquid hydrogen tank had come loose. To fix it the Ariane 5 had to be rolled back to the assembly building causing a delay of three or four days.
Again the delay played in my favour. My colleague had an appointment (unrelated to Rosetta) to visit a ground station on the other side of the Guiana Space Centre and we happened to pass the launch area just in time when the Ariane 5 was rolled back to the assembly building (see the picture). It is only during those occasions that ordinary people have a chance to see an Ariane 5 up close as during the actual launch you are much farther away.
The next launch attempt was at 4:17 local time on 2nd March. Another bonus of the delay was that by now the group of VIPs which had been invited to see the launch had returned home and we were "upgraded" to the better observation sites. I ended up in the launch control room (or rather in the viewing gallery behind a large glass wall of that room).
Although the weather had been marginal with rain showers and heavy clouds the countdown proceeded smoothly. Exactly one minute prior to liftoff side doors opened and we could go out to a balcony looking straight toward the launch complex. There was no mistaking the liftoff when the night suddenly turned as bright as in the middle of the day.
Although the Ariane 5 disappeared into the clouds some 15 seconds after lift off it was then that the most interesting show began with the clouds suddenly being illuminated from above and the rocket reappearing through a gap in the clouds displaying a long trail of fire which we could follow for about a minute. You could sense the enormous power of such a rocket.
Once we lost sight of the Ariane 5 we had to rely on large computer displays and commentaries to follow the further progress of the flight. On a standard Ariane 5 launch the insertion orbit will be reached after half an hour. But for Rosetta a different procedure was required. A first burn put Rosetta into an elliptical orbit of 200 km x 4000 km altitude and after almost one revolution 2 hours later a second burn would propel the spacecraft into its desired escape trajectory.
This meant that we couldn't party straight away but rather had to bite our nails. Actually breakfast had been arranged to fill the gap. Finally we got news that the second burn had been successful and Rosetta was on its way - at long last the Champagne bottles were opened!
Although launch delays are taxing on mission personnel involved (let alone the spectators) they proved to be benificial for Rosetta. The launch window had been three weeks. Launching at the very beginning or end of such a window will satisfy mission requirements with certain margins but the optimal launch conditions are typically in the middle of the window.
As it turned out due to the delay the actual launch of Rosetta occurred at almost the optimal day. In addition the insertion by the Ariane 5 had been extremely accurate saving fuel which had been set aside to correct for launch errors. As a result Rosetta started out with more fuel than needed for its prime mission. This allowed mission planners to include two "scenic detours" to two particularly interesting asteroids. While asteroid Steins has already been passed in September last year there will be a flyby of asteroid Lutetia in July next year.
After that Rosetta will be put in hibernation for two and a half years. Due to its large distance from the Sun there is very little power left so most systems will be turned off and there will be no communication. Only at the beginning of 2014 will we be contacting Rosetta again. This is almost like in times long past when ships set sail on historic voyages of discoveries and they were cut off from their home ports for two or three years until they returned with exciting news about new worlds.
Meanwhile I'm still able to see Rosetta. Not the actual flight model which is quickly receeding from Earth but the engineering test model of Rosetta is at the European Space Operations Centre (ESOC) in Darmstadt. It is very useful for testing new procedures or sort out problems if they occur on such a long mission. It's also one of the attractions for visitors at ESOC who can get a better idea how such a spacecraft looks like in real life.
And if I take visitors on a tour around ESOC I can tell them about those tarantulas at the launch site...
The European spacecraft Rosetta just passed Earth on its final gravity assist maneuver enroute to a historic rendezvous with a comet. Go-For-Launch co-blogger Michael Khan has given a detailed description of this third flyby. For me it brought back memories of the launch which I had the privilege of witnessing on the spot.
Rosetta had been ready to depart in January 2003 to Comet 46P/Wirtanen when the month before an uprated Ariane 5 rocket experienced a failure. This caused the delay of all further Ariane launches to sort out the problem. As flights to rendezvous with comets require complex trajectories with very specific launch dates a new target needed to be selected.
Analysis showed that Comet 67P/Churyumov-Gerasimenko could be reached by Rosetta in its original configuration with a launch date of February/March 2004. This new date allowed me to get an invitation to watch the launch in Kourou thanks to a colleague of mine.
With launch slated at 4:37 local time on February 26th we had to get up at around 2 o'clock. There was some mild chaos in the hotel lobby where we were assigned to the busses which would bring us to the various observation sites. I ended up on a hill overlooking the whole space complex some 13 km from the actual launch site. (A neigbouring hill is open to the general public to follow launches without invitation. Information about visiting the Guiana Space Center in Kourou can be found here.) Other observation sites (by invitation only) are the very control room and a place a little over 5 km away from the launch complex.
Arriving about half an hour before the planned liftoff there was just enough time to spot a pair of tarantulas (better watch your step at these early hours in the morning) when we were told that the launch was off due to excessive wind speed. (The Ariane 5 could have launched under these conditions but if the wind blows from the wrong direction debris and toxic gasses might reach the nearby town in case of an accident.)
Another launch attempt was being made the next night but this time we only got as far as the hotel lobby where a note was put that the launch had been postponed again. A piece of insulation of the liquid hydrogen tank had come loose. To fix it the Ariane 5 had to be rolled back to the assembly building causing a delay of three or four days.
Again the delay played in my favour. My colleague had an appointment (unrelated to Rosetta) to visit a ground station on the other side of the Guiana Space Centre and we happened to pass the launch area just in time when the Ariane 5 was rolled back to the assembly building (see the picture). It is only during those occasions that ordinary people have a chance to see an Ariane 5 up close as during the actual launch you are much farther away. The next launch attempt was at 4:17 local time on 2nd March. Another bonus of the delay was that by now the group of VIPs which had been invited to see the launch had returned home and we were "upgraded" to the better observation sites. I ended up in the launch control room (or rather in the viewing gallery behind a large glass wall of that room).
Although the weather had been marginal with rain showers and heavy clouds the countdown proceeded smoothly. Exactly one minute prior to liftoff side doors opened and we could go out to a balcony looking straight toward the launch complex. There was no mistaking the liftoff when the night suddenly turned as bright as in the middle of the day.
Although the Ariane 5 disappeared into the clouds some 15 seconds after lift off it was then that the most interesting show began with the clouds suddenly being illuminated from above and the rocket reappearing through a gap in the clouds displaying a long trail of fire which we could follow for about a minute. You could sense the enormous power of such a rocket.
Once we lost sight of the Ariane 5 we had to rely on large computer displays and commentaries to follow the further progress of the flight. On a standard Ariane 5 launch the insertion orbit will be reached after half an hour. But for Rosetta a different procedure was required. A first burn put Rosetta into an elliptical orbit of 200 km x 4000 km altitude and after almost one revolution 2 hours later a second burn would propel the spacecraft into its desired escape trajectory.
This meant that we couldn't party straight away but rather had to bite our nails. Actually breakfast had been arranged to fill the gap. Finally we got news that the second burn had been successful and Rosetta was on its way - at long last the Champagne bottles were opened!
Although launch delays are taxing on mission personnel involved (let alone the spectators) they proved to be benificial for Rosetta. The launch window had been three weeks. Launching at the very beginning or end of such a window will satisfy mission requirements with certain margins but the optimal launch conditions are typically in the middle of the window.
As it turned out due to the delay the actual launch of Rosetta occurred at almost the optimal day. In addition the insertion by the Ariane 5 had been extremely accurate saving fuel which had been set aside to correct for launch errors. As a result Rosetta started out with more fuel than needed for its prime mission. This allowed mission planners to include two "scenic detours" to two particularly interesting asteroids. While asteroid Steins has already been passed in September last year there will be a flyby of asteroid Lutetia in July next year.
After that Rosetta will be put in hibernation for two and a half years. Due to its large distance from the Sun there is very little power left so most systems will be turned off and there will be no communication. Only at the beginning of 2014 will we be contacting Rosetta again. This is almost like in times long past when ships set sail on historic voyages of discoveries and they were cut off from their home ports for two or three years until they returned with exciting news about new worlds.
Meanwhile I'm still able to see Rosetta. Not the actual flight model which is quickly receeding from Earth but the engineering test model of Rosetta is at the European Space Operations Centre (ESOC) in Darmstadt. It is very useful for testing new procedures or sort out problems if they occur on such a long mission. It's also one of the attractions for visitors at ESOC who can get a better idea how such a spacecraft looks like in real life.And if I take visitors on a tour around ESOC I can tell them about those tarantulas at the launch site...
