Rumour has it that although the Viking Orbiters are not being tracked anymore as they are silent since early 1980s, one of them has actually been spotted by Spirit. Any info on that?

Also, I wonder how many orbiters from the early era of Mars exploration are still around... Have any of them impacted Mars upon orbital decay? Is Mariner 9 still around? And how about the Russian orbiters?

Regards,

Karol P.
Poland

Hi Karol, we've had a few discussions regarding these matters, but opinions *do* vary. Generally, most of the orbiters are still likely to be up there. The MERs have looked at the night sky and seen various objects, but I've not heard specifically that either of the Vikings were identified. What they have certainly seen are Earth, Jupiter, and some meteors (and Phobos and Deimos!).

Bob Shaw

Mariner 9 and the Viking orbiters were deliberately placed in orbits
around Mars where they would remain in space for at least fifty
years to kill off any stray microbes that might have hitched a ride
to avoid contaminating the planet when they do finally crash on it.

Maybe, just maybe, a future expedition could recover them for
study and exhibition, thus avoiding their touching the Red Planet
at all. Unless they are placed on Mars.

Can't say what the status or contamination protocols are for the
Soviet orbiters or the newest crop of similar vehicles.

BTW, is this the image you are referring to (scroll down 2/3 of the way):

http://marsrovers.jpl.nasa.gov/gallery/pre.../20040311a.html

From the accompanying text:

It's a Bird, It's a Plane, It's a... Spacecraft?

Observing the sky with the green filter of it panoramic camera, the Mars Exploration Rover Spirit came across a surprise: a streak across the sky. The streak, seen in the middle of this mosaic of images taken by the navigation and panoramic cameras, was probably the brightest object in the sky at the time. Scientists theorize that the mystery line could be either a meteorite or one of seven out-of-commission spacecraft still orbiting Mars. Because the object appeared to move 4 degrees of an arc in 15 seconds it is probably not the Russian probes Mars 2, Mars 3, Mars 5, or Phobos 2; or the American probes Mariner 9 or Viking 1. That leaves Viking 2, which has a polar orbit that would fit with the north-south orientation of the streak. In addition, only Viking 1 and 2 were left in orbits that could produce motion as fast as that seen by Spirit. Said Mark Lemmon, a rover team member from Texas A&M University, Texas, "Is this the first image of a meteor on Mars, or an image of a spacecraft sent from another world during the dawn of our robotic space exploration program? We may never know, but we are still looking for clues."

Thanks a lot, that answered the second question that bothered me for some time, namely how many orbiters are left up there. Phobos 2 is in orbit around Mars, so I guess Phobos 1 did not make it and simply flew by the Red Planet. But how come Phobos 2 did not send any data if it DID succeed in achieving the intended orbit?

It did...Here is a link to some of its images that I worked on.

http://pages.preferred.com/%7Etedstryk/phobos2.html

It also returned some interesting results from its other instruments.

I am impressed! Not only with the colour Phobos imagery, but the whole site as well. Some of the Soviet images from Venera and Luna landers were published in Polish books. A friend of mine also enjoys playing with planetary imagery. He has also made an animation of the first triple asteroid - Sylvia, based on a scientifically accurate shape model:

http://republika.pl/moonlets/animacje.html

Perhaps you would enjoy his planetary moons website as well (all translated nicely into English):

http://republika.pl/ksiezyce/

He is experimetning with maps of the larger moons, like this one:

http://republika.pl/ksiezyce/neptune/triton_en.html

(you need to click on the image to open a popup, then "activate" rotation and rotate using any key)

And, he has made rotating maps for many other moons, all of which are accessible from this huge table:

http://republika.pl/ksiezyce/table_en.html#Table

The ones with rotating maps have a tiny blue ball next to their names.

Thank you for the link to the planetary moon website karolp.
That was a source I was happy to make at bookmark for.

And yes Phobos 1 died enroute due to a faulty computer.
My information on Russian space back in those days came mostly from books that was published about a year or more after. We did have a few newspaper items on this mission though since several european countries had a stake in this mission, and I do remember feling disappointment over one uneven colour image with Phobos over the limb of Mars. Im quite certain its the one tedstryk have on top of his webpage, but quite reprocessed making it look quite better now.

As for sceience return, Phobos 2 did not return much information, it ceased not so long after having achieved orbit, contact was lost when it was set to approach Phobos.

The soviet time Russians had done the Venera series all on their own as well as the Mars series so this Phobos mission can in fact be seen as a start for the kind of cooperation that are so common today between Russia, ESA and the US space agency.

Some years after we learned that it had been known that Phobos 1 & 2 had faulty computers before launch, but that it was decided to take a gamble with these two probes.
And thats a bit sad when you consider the fact that they had invited several european partners for this project. Perhaps they felt a pressure to go ahead for this very reason, and that might very well have been the case.

The Phobos missions were supposed to be the start of the Soviet Union's
plans to place cosmonauts on Mars by 2015. But between their failures
and then the major changes in the USSR during 1989-1991, that plan
obviously fell by the wayside.

Regarding the failure of Phobos 1, this is from the Wikipedia entry:

"Phobos 1 operated nominally until an expected communications session on 2 September 1988 failed to occur. The failure of controllers to regain contact with the spacecraft was traced to an error in the software uploaded on 29 August/30 August, which had deactivated the attitude thrusters. By losing its lock on the Sun, the spacecraft could no longer properly orient its solar arrays, thus depleting its batteries."

http://en.wikipedia.org/wiki/Phobos_program

Poor Phobos 2 was just a week away from deploying a lander and a hopper
on the moon when things went wrong. Sadly the probe design had it turning
the communications dish away from Earth when the probe was taking images
and other data. Well, finally at some point the probe did not turn back properly
and despite a few transient signals, the craft and mission were lost.

Supposedly Phobos 2 might have eventually crashed into the moon. Has anyone
here or elsewhere tracked this possibility?

The lander actually carried an engraved copy from Asaph Hall's notebook
from when he discovered the Martian moons in 1877, to be deposited on
the surface. Sky & Telescope had a photo of the plaque circa 1988.

http://en.wikipedia.org/wiki/Phobos_%28moon%29

Myran:

I think the faulty computer story was originally attached to some of the earlier Mars-series of spacecraft, not Phobos 1 & 2, the demise of which were, so far as I know, as described above.

The full list of Mars Orbiters is:

Mars 2
Mars 3
Mariner 9
Mars 5
Viking 1 Orbiter
Viking 2 Orbiter
Phobos 2
Mars Global Surveyor
Mars Odyssey
Mars Express
Mars Reconnaissance Orbiter

Some Mars Climate Orbiter debris *may* have attained temporary orbit; the two Viking bioshield caps may also be in orbit.

Bob Shaw

Thank you for the correction Bob Shaw.
Yes that about the computers might have blended in my memory, the rest should be correct though. That the dual Phobos mission was unusually open as for the information by Soviet standards and it recieved considerable interest here in Europe as long they did last.

At the time it WAS reported that the triplet computers had gotten in conflict though, I will check on this matter and get back if I find something more on the subject.

Edit:

"Phobos 1 operated nominally until an expected communications session on 2 September 1988 failed to occur. The failure of controllers to regain contact with the spacecraft was traced to an error in the software uploaded on 29/30 August which had deactivated the attitude thrusters. This resulted in a loss of lock on the Sun, resulting in the spacecraft orienting the solar arrays away from the Sun, thus depleting the batteries.

Phobos 2 operated nominally throughout its cruise and Mars orbital insertion phases, gathering data on the Sun, interplanetary medium, Mars, and Phobos. Contact was lost shortly before the final phase of the mission, during which the spacecraft was to approach within 50 meters (110 feet) of Phobos' surface and release two landers, one a mobile 'hopper', the other a stationary platform. The mission ended when the spacecraft signal failed to be successfully reacquired on 27 March 1989. The cause of the failure was determined to be a malfunction of the on-board computer."

Phobos 1 was lost due to the software, and Phobos 2 due to the computer went on the blink.
Im pleased to say we both got it right.

Was Phobos 1 also moon science or was it going into Mars Orbit?

Both were intended to operate in orbit around Mars, and to study Phobos. And Mars.

Bob Shaw

He has some really cool stuff!