[X] My Assistant

[dvandorn]

Just to start a general topic, we've discussed some aspects of the old Soviet planetary exploration programs, but we've never had a topic devoted to the discussion, where we can discuss it in general terms.

So, the question is, did the Russians have significantly more problems with their early lunar and planetary probes than the U.S. did? How about ESA or JAXA? How do they all compare?

And what would y'all say is the reason for differences in success/failure rates, and quality of data returned, by probes built and flown by the various polities which have attempted them thus far?

I can think, specifically, of Russian lunar orbiters that returned image data of far poorer quality and usefulness than contemporary American orbiters... of the '71 Mars debacle, in which a functioning Soviet orbiter couldn't be re-targeted real-time and spent all of its pre-planned science program photographing the blank, featureless top of a global dust storm... of more than their fair share of probes ending up as junk decorating the steppes of Kazakhstan.

But, then again, you can always bring up the failures of Rangers 1-6, two of the seven Surveyors, the partial failure of Lunar Orbiter 1, etc., etc., etc., while the Russians were merrily taking pictures (albeit low-quality ones) of the far side of the Moon and landing small pods on its surface.

What do y'all think the balances were? What learning-curve lessons-learned are we seeing repeat themselves in the ESA and JAXA programs?

Just trying to get a sense of the group on this one.

-the other Doug

[GregM]

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[Stephen]

Space probes have failed in the past and will doubtless do so again in the future. America has had to endure losses to its own Mars program, but unlike those on the Soviet/Russian program they have all been isolated cases. Doubtless each can all be sheeted home to particular causes, some preventable, others less so.

Long strings of repeated failures, on the other hand--like America's Rangers 1 through 6, and the Soviet/Russian Mars probes--are an entirely different matter. They surely point to more of a systemic problem (or problems) behind the failures. Simply figuring out what went wrong on a failed probe and correcting it is on the next attempt may fix an isolated failure but it is less likely to deliver a success if the real problem is not with the probes themselves. For even if the engineers prevent the last problem happening again there will probably be another problem waiting in the wings to bring you (and your probe) back down to the proverbial earth.

In that context to have such a long string of failures (and over such an extended period) as the Soviet Mars program had surely does point to an inherently flawed program. That does not mean Soviet engineers were any the less brilliant or inventive. It simply means that something in or about the program itself, or the way it was run, was defeating their efforts.

I do not pretend to know what that factor was or the systemic flaw or flaws were. I can only point to the statistics. That said consider the orbiter part of Mars 2, which arrived at the Red Planet in 1971. Technically Mars 2's orbiter was not a failure. AFAIK the hardware performed flawlessly. It arrived safely and did what it had been built to do. Yet that orbiter returned no useful imaging data because it happened to arrive during one of the largest global dust storms in modern martian history. Now you could put that down to sheer bad luck. Yet America's Mariner 9 was potentially in the same boat. When it arrived it too was faced with that same global dust storm obscuring the entire planet.

The difference was that whereas the Americans could re-program their probe and get it to sit the dust storm out the Soviets could not. They had foolishly given it a pre-programmed course of action which could not be changed.

To put it another way, by sending off Mars 2 on a pre-programmed mission the Soviets actually were relying on luck. And blind luck at that. They were relying on there being no problems at the Mars end of the mission.

Unfortunately, Mother Nature failed to cooperate. It threw both the Soviets and the Americans a nasty curve ball in the form of that dust storm. But whereas the Americans had enough foresight to send a probe which could handle the unexpected the Soviets chose to send one which could not.

That raises the question of what proportion of the other Soviet failures were due to the probes being unable to cope with the unanticipated?

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Stephen

[Guest_DonPMitchell_*]

The difference was that whereas the Americans could re-program their probe and get it to sit the dust storm out the Soviets could not. They had foolishly given it a pre-programmed course of action which could not be changed.

This is incorrect. Mars-3 took pictures on command and took many photos after the dust storm was over. The problems with Mars-2 and Mars-3 were related to their radio systems.

Mars-3 had a couple programming modes for photography. It would always take a sequence of 12 photos at once, and the film magazines held 480 frames. It could be commanded to orient itself using an infrared horizon and then take the photos, or it could be sent a detailed 3-axis orientation. Most of the photos I've seen were taken in the latter mode, while the probe was fairly far out in its elliptical orbit and showing the whole planet.