[X] My Assistant

[Guest_BruceMoomaw_*]

http://www.nasawatch.com/archives/2006/05/...finally_so.html : "Yikes! ITAR issues aside, it is obvious why NASA sat on this report for a year -- it has a high embarassment coefficient."

I put this report in this place on the website because of the crucial importance of robotic rendezvous and docking to Mars sample return. Overall causes of the failure were our familiar old friends: too small a team, lack of a systems engineer, over-hasty schedule, and above all "High Risk, Low Budget Nature of the Procurement". Seems to me I've heard that song before...

[Guest_BruceMoomaw_*]

Two of my sources E-mail me to tell me I'm partially mistaken about saying that DART would just have repeated what "the Russians have been routinely doing for 39 years." First:

"From what I know of the 'KURS' docking system the Russians used (I don't know if they still use it) this isn't a valid comparison. The way I understand things, the Russians flew their vehicles up to proximity operations space (i.e. they did the rendezvous maneuvers) from the ground, and then the KURS system only took over when they got within some prox-ops boundary (i.e. 250 m) -- at which point KURS, which is a simple computer that reacts to radar signals from the target and the chaser, fires the engines to line the vehicle up and dock it.

"Not only isn't this part very hard, but KURS also relies on intervention from the ground when it screws up, which it regularly does, or at least did during the MIR days.

"DART, on the other hand, flew all the way from launch without any possible intervention from the ground, and it flew the whole rendezvous part and the prox-ops part autonomously and bullseyed the MUBLCOM spacecraft using GPS and other onboard orbit determination stuff that has never been tried before.

"Several very smart friends and collegues of mine worked among the Orbital Sciences engineers after the DART Mission to figure out what went wrong, and their response was very similar to this report -- i.e. that this was ultimately a very successful mission on which a whole lot of very new technologies worked very well. In the end the hardware all worked, and everything was there for the mission to be successful, but some poor software testing screwed them. The fix is very simple. The system would work as-is with the software fix.

"I try not to spend much of my time apologizing for NASA, and I certainly think the ITAR crap that they are using to hide the real report here is a crock. That said, I think it is incorrect to characterize this mission as a complete failure. It was a difficult set of problems, and they almost got all of them right on the first try.

"As far as I know, the Russians have never done anything like this, and I don't even know that they can build the KURS system any more. They were having a hell of a time doing so during MIR. I recall hearing that they had to recycle the computer out of old Soyuz modules because they couldn't build them and the Ukranians didn't want to sell them any new modules for a reasonable price."

Second (from Jeffrey Bell): "Actually, they haven't [been doing what DART tried for 39 years]. Progress auto-dockings frequently fail in the later phases, and humans have to take over manual control with a Mk1 Mod0 eyeball and joysticks."
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My initial reply is that I stand partially corrected -- but the facts remains:

(1) This docking system OFTEN works fully automatically for the Russians, whereas the US hasn't yet done it successfully once -- and...

(2) It shouldn't be that much harder for a spacecraft to carry out the pre-docking rendezvous sequence autonomously, using data which it acquires from GPS rather than from ground tracking stations, and/or using autonomous optical sightings of the target in orbit (such as many manned crews have done using a sextant and computer). I still think there is no excuse for a screwup this big, and I still think that Goldin's stupid semi-religious belief in Faster-Better-Cheaper claimed still another victim this time.

This, in turn, has ignited a further multiple exchage between me and my different sources on just how innovative and how successful DART really was -- which I'm still trying to digest. More details later (I hope).