Har har...think I'll try to undercut him by offering all of the Russian landers in a package deal (as-is with no warranties, of course)!

Oh, gadfry, Messenger, are you still peddling that stuff about major violations of the laws of gravity elsewhere in the Solar System? Especially when the only thing we need to explain these crashes is the major fluctuation in Mars' air density already known to exist?

And Mars 3, don't forget, actually made it to the surface -- it just broke down, for unknown reasons, 90 seconds later. V.S. Perminov, who was associated with the Soviet Mars program, writes that he suspects a static discharge caused by the major planetwide dust storm in which Mars 3 landed as a possible cause (and, in fact, static discharge was also listed as one of the multitude of possible causes for the Deep Space 2 failures).

He also provides -- for the first time, I think -- an explanation for the Mars 2 crash: because of the Soviets' lack of faith in the quality of their own deep-space radio tracking, the craft was equipped with its own Autonav system that sighted on Mars several days before encounter and made a final automatic course correction to put the lander into the right entry corridor. But because the Soviets had slightly incorrrect data on Mars' true ephemeris (which, ironically, was corrected only a year later during the US/Soviet exchange of planetary probe information), the lander entered at too steep an angle and therefore crashed (shades of Mars Climate Orbiter!) He doesn't speculate on the cause of the Mars 6 failure -- although, given all those crumbling transistors on the 1973 Mars probes, it may simply have failed to fire its last-second retrorocket.

I should add that the Polar Lander failure report does not list lower-then-expected air density as a possible cause for that failure -- and the software flaw discovered by the Board is fully adequate by itself to explain that crash (although it's always possible that something else wrecked the mission even before then, since a number of possible alternative causes ARE listed).

Note that the Viking landers directly measured the gravity of Mars while sitting on the surface with their entry/descent accelerometers and got a decently accurate estimate for each lander of it's radius from the center of the planet. That would not have been possible if there were non-square root, or non-trivial "second order" whatever that means in this context, deviations in Mars' gravity from that determined by inter-planet peturbations, flyby estimates, and orbital measurements.

Messenger's gravity 'thing' has appeared here before, and he was suspended from the forum for a month for continually spouting pseudo science.

Infront of everyone here - go down that path again, and I'll just ban you. I'm not having that pseudo-science junk in this place. Speculation, yes. Discussion, yes. Debate, yes. Crap? No.

Doug

Well, I cannot make up anything from the images and I guess we shall have to wait untill Mars Reconnaissance Orbiter is operational in April - May 2006...

Meanwhile:


Merry Christmas & Enjoy the end-of-year period !!!

... all the best for the New Year 2006 !!!

I remember reading that Mars 3 may have kept working just fine on the surface - it was the orbiter that somehow lost the link with the lander. Any details on this?

I wonder if it stored any data onboard? Would it still be readable if so? Yes, I realize I am talking about a 1971 Soviet computer.

Enclosed is the data from astronautix web page about Mars 3 correspondient to Soviet unmmaned space M-71 :May 1971 Mars 3 Program: Mars. Launch Site: Baikonur . Launch Vehicle: Proton 8K82K / 11S824. Mass: 4,643 kg. Perigee: 1,528 km. Apogee: 214,500 km. Inclination: 60.0 deg.:
The descent module (COSPAR 1971-049F) was released at 09:14 GMT on 2 December 1971 about 4.5 hours before reaching Mars. Through aerodynamic braking, parachutes, and retro-rockets, the lander achieved a soft landing at 45 S, 158 W and began operations. However, after 20 sec the instruments stopped working for unknown reasons. Meanwhile, the orbiter engine performed a burn to put the spacecraft into a long 11-day period orbit about Mars with an inclination thought to be similar to that of Mars 2 (48.9 degrees). Data was sent back for many months.

Cherry Christmas

Rodolfo

A couple of points:

MRO's mapping orbit isn't at 150 km -- it's between about 250 km and 320 km. Early in mission planning a lower periapse was considered, but this wasn't chosen.

Both MGS and I believe Odyssey routinely went below 150 km during aerobraking.

Bummer. The mapping will provide much more detail, and hopefully provide better insight into what is proving to be the ellusive - the moment of inertia.

I think it is how the degeneracies in the harmonics have been identified, but I do not fully understand the details.


It would be fun to send one of the MER's on a long-hull mission to check it out...extend the mission to 2304...

Mars 3 impacted at about twice the expected velocity (~20m/s), but was designed to withstand such an impact. Since little in the way of lightning has been noted by MER's in a year of exploration, the possibility that the quick zap out was due to static effects is appearing less likely.

http://klabs.org/richcontent/Reports/mars/...oad_to_mars.pdf
(Soviet Report on the Difficult road to Mars, this is a good read.)

http://nssdc.gsfc.nasa.gov/database/Master...og?sc=1971-049F

The surface gravity numbers I have for the Viking probes are 1.5% above NASA's currently published estimate (3.725 Viking mean, current NASA: 3.71m/s^2), but I do not know how this current value was derived. Until the moment of inertia is pinned down, the unknown mass distribution limits the resolution of the surface gravity.

http://techreports.larc.nasa.gov/ltrs/PDF/...76-cr159388.pdf
(Vintage Viking document, also a fun read)

As per Doug's request, I will keep my speculations-as-to-cause off the board, but everyone appreciates the importance of noting and trying to understand the cause of anomalies.

This board is too good to miss - for any reason.

Thanks to The Messenger for the references which are very good.

Rodolfo

Talking about spacecraft that kept working...
I believe that of the 1997 Pathfinder-Sojourner combination, first the base station failed meaning that the little rover couldn't get nor send images/instructions.
The rover had a tiny heat source of its own and it was designed to start up again if it didn't hear from Earth for 7 days ...

Yep. The rover was also programmed, if it didn't hear from the lander after a certain time, to assume that it might have wandered into a terrain feature that was blocking the radio signal, and to then automatically drive in a curve until it heard from the lander again. Nobody knows how far the Little Lost Rover drove after the lander failed, calling futilely for Mama. Pathetic, isn't it?

Bruce, you just blew out my anthropomorphometer!

Though I too have imagined the lil' puppy rover wandering..... and wondering where momma went... *sniff*

Uh, sorry, must have got something caught in my eye....

Hang in there little guy!)

And to get back on topic of the current thread's canine, I remain highly skeptical that this is really Beagle.... I hate to say the P Word, but this seems right on the edge of perception. We will see I guess, or not!

Just a hypothetical thought here - but say for example Beagle 2 DID land successfuly in the location the Beagle 2 team are suggesting but missed the crater it "might" be resting in by a few metres. Would the probe have continued to bounce and roll right into the giant crater to the right?

It might be. However, up to now, we are not wearing the proper eyeglasses so we cannot see any good pictures until after MRO starts to work...Hope that the end of the year 2006 we are going to have a much better eyeglasses to spot with certainity to Beagle 2.

Rodolfo

Don't know if You all noticed the redesign of the Beagle 2 website, which now focuses on the images of the possible location of the ill-fated Beagle 2 lander:

http://www.beagle2.com/index.htm

Philip

It would have been interesting, had MGS been in an appropriate orbit at the time (I think it had just arrived when Pathfinder failed, but it may not have been there yet - at best, it was in a looping orbit not suitable to look for a lander), might it have at least picked up that Sojourner was transmitting. Pathfinder suffered from having to operate with no orbiter support, both in terms of data transmission and the fact that its site had to be picked from old kilometer-scale Viking images.

Sojourner was on 459.7 MHz, and MGS Relay is on 401.5275 MHz and 405.6250 MHz.

Soj-MPF was 9600 bps I think, where as MGS relay is 8 or 128.

I'm not sure if any other assets might have been able to listen in on Sojourner directly, but I dont think MGS could

Doug