ESA
English
Français
DeutschTeamwork & sweat: ESA's Bob Chesson explains ATV propulsion problem and how it was solved
We've got a series of great mp3 audio clips from a telephone call with ESA's Bob Chesson with a detailed explanation on the propoulsion problem involving the PDE (Propulsion Drive Electronics) that caused excitement on Sunday evening, shortly after orbit injection. The problem's now solved, but Bob mentions what caused the issue to occur, the solution and the incredible teamwork (Astrium, ESA, CNES) behind devising and implementing the fix (click on 'Full story' to access mp3 links). -- Daniel
Admittedly, the audio is a little techie - but after all, it **is** rocket science. 
ESA's Bob Chesson is located at ATV-CC in Toulouse, and as the head of the Human Spaceflight Operations team, he's watching every minute of ATV operations very closely. He has first-hand participation in all aspects of ATV activities and spoke to us yesterday on the PDE (Propulsion Drive Electronics) problem.
First off, here is Bob describing the origin of the problem. In the audio, he mentions the two propulsion reactants: "MON" and "MMH" - these are the oxidising agent, MON (mixed or modified oxides of nitrogen) and the fuel itself, Monomethylhydrazine (MMH). These are examples of so-called 'hypergolic' reactants, which ignite spontaneously when they come into contact. Due to their reliability, hypergolic systems are widely used by many spacecraft and rockets, including ATV, the Shuttle, Ariane and others.
Next, Chesson explains the fix: essentially, a set of new commands that were devised by engineers at Astrium, builders of the ATV, tested by Astrium with their engineering model of the ATV and by the ATV mission controllers using their simulation software, and then radioed up to ATV. In the audio, Chesson mentions "OMP" commands - these are Onboard Mission Plans that are uploaded to the Jules Verne computer for subsequent execution.
At the end, Chesson mentioned several times the immense teamwork displayed by everyone involved in the mission: prime contractor Astrium, ESA, CNES and ATV-CC - plus many sub-teams within these organisations. Bob mentions the Astrium engineers - they are working, in part, at the Astrium facility at Les Mureaux, France, where the contractor's core design and qualification teams for ATV are on stand-by.
13-03-2008 • 19:20:10
congratulations BOB, that is very good news for the complition of this wonderfull mission. I appreciate very much your comments on the very good spirit among the team, I which you to continue in such beautiful manner
Meilleurs souvenirs
JCC
14-03-2008 • 13:28:13
Dear authors,
the problem is a pressure regulator issue, as explained, and has nothing to do with the PDE itself. The behavior of the PDE is nominal as required. So the headline is missleading!
14-03-2008 • 14:22:55
Thanks Joachim; you are correct. I've updated the title. -- Daniel
15-03-2008 • 02:15:16
Thanks for so much insight into the information that is flowing with the mission right now. Very appreciated, and a great precedent to how ESA should present its missions.
Thanks for the effort of keeping this so well mantained and up to date. Greetings from Spain,
David
25-03-2008 • 17:05:58
I am amazed and very proud of this pioneering European ATV venture but am saddened that such a useful piece of space hardware is to burn up.
Could a future ATV with twin docking ports self-build a new lego space facility? The solar panels alone would have added a significant power boost to the ISS when plugged in by the new robot.
I await successful docking with the ISS with great interest.
Many thanks
25-03-2008 • 17:36:48
Hi RW,
Thanks for your note. No doubt, ATV is a useful vehicle! But it was strictly designed to deorbit and burn up once its useful life as an ISS module finishes. Your idea to re-use the solar arrays on the ISS is not a bad one, but I can speculate that the engineering & design requirements for such a 'transferable solar array system' would be large and well beyond the planned scope (and funding) of the ATV's basic design. For example, solar arrays that are designed to power the ATV through self-powered flight (light-weight, folding, etc.) are likely not the same type of design that the ISS would need. You may be pleased to know that, in fact, there have already been several initial studies done on the ATV's future evolution, including scenarios where it is fitted with a parachute re-entry pod, fitted with a crew pod, or twined up with a second ATV to boost cargo capacity, etc. Anything is possible (more or less) and everything depends on how the ISS evolves in the coming years. -- Daniel