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J.J.
I was wondering if anyone here knew how many sols Viking 1 and Viking 2 operated on Mars, for comparison purposes. I know the basics (that Viking 2 went out in 1980, and Viking 1 two years later), but the actual numbers of sols would be appreciated.

Thanks in advance!

-J.J.
jamescanvin
Wow, how many times has this question been asked here now? blink.gif

Viking 1 - 2245 sols
Viking 2 - 1281 sols

cf. Design liftime 120 sols

James
tedstryk
Viking 2 - 1281 Sols, after which its batteries failed.
Viking 1 - 2,245 Sols, when it was turned off by a bad command.
centsworth_II
QUOTE (tedstryk @ Sep 21 2006, 07:54 PM) *
... when it was turned off by a bad command.

I assume there is positively, absolutely no way this could happen with the MERs. . . . Right?
djellison
There's always a way where by you could turn a spacecraft actually off. BUT - it would have to be very very deliberate.

Doug
edstrick
"Viking 1 - 2,245 Sols, when it was turned off by a bad command."

Viking 1 was in an entirely automated mission with the commanding team pretty much disbanded when it started to show signs of battery failure similar to those that killed (actually disabled) Lander 2 shortly before Lander 2's only link to Earth (via Orbiter 1, both direct-to-Earth-transmitters were dead).

A group was assembled to design and uplink a battery conditioning sequence and it was transmitted to the spacecraft, which was never heard from again. They believed that the code inadvertently overwrote the code for calculating the position of the Earth in the sky for automated transmissions in the blind to the ground.

They tried to calculate when Earth would be in the line of site of the mis-pointed antenna (apparently it was expected to be doing weird wanderings across the sky) and get new commands uplinked, but nothing they tried resulted in further contact. It's plausible -- even PROBABLE -- that battery failure finally caused the spacecraft to permanently safe-mode in some fashion, but we'll never know until and if the memory and tape recorder on the spacecraft are directly examined.
NoVi
QUOTE (djellison @ Sep 22 2006, 07:00 AM) *
There's always a way where by you could turn a spacecraft actually off. BUT - it would have to be very very deliberate.

Doug



something like this

if actual_cost > budget
and budget_approval false
then shutdown_mer

biggrin.gif
J.J.
Thanks much, all. smile.gif
helvick
Sad and all as that code might be at least it would be better than some dodgy autonomous navigation code that caused Oppy to continue to driver over a cliff rather than stopping. Here's looking forward to plenty of sanity checking tests over the next few days. I'm in absolutely no hurry to see more pictures.
gndonald
QUOTE (edstrick @ Sep 22 2006, 04:31 PM) *
They tried to calculate when Earth would be in the line of site of the mis-pointed antenna (apparently it was expected to be doing weird wanderings across the sky) and get new commands uplinked, but nothing they tried resulted in further contact. It's plausible -- even PROBABLE -- that battery failure finally caused the spacecraft to permanently safe-mode in some fashion, but we'll never know until and if the memory and tape recorder on the spacecraft are directly examined.


Do you know if anyone at NASA has tried to use any of their currently orbiting satellites (MGS/Mars:Odyssey) to listen for, or to beam signals to Viking One just in case it is still in a workable condition, however unlikely it may be?
djellison
I would be utterly amazed if MGS, Odyssey, MRO or MEX could use UHF in a way that would be compatable with the Viking landers.

(update - infact, it's a no. The Viking UHF was around 381Mhz, whereas modern Mars Relay operations are conducted at the 430ish range )

Doug
Paolo
QUOTE (tedstryk @ Sep 22 2006, 01:54 AM) *
Viking 2 - 1281 Sols, after which its batteries failed.


I may be wrong, but I remember that Viking 2 was shut off after its high gain antenna failed and the orbiter relay had to be discontinued due to... well, lack of orbiters!
tedstryk
QUOTE (gndonald @ Sep 22 2006, 02:44 PM) *
Do you know if anyone at NASA has tried to use any of their currently orbiting satellites (MGS/Mars:Odyssey) to listen for, or to beam signals to Viking One just in case it is still in a workable condition, however unlikely it may be?


Its RTG would have hit a level in the early 1990s where it wouldn't have had enough power to operate. Had Mars not gone 17 years without an orbiter, excluding the three month Phobos-2 interlude, this might have been possible, but the chance of it now is gone.
edstrick
Viking 2 suffered battery failure shortly before its last links to earth were severed by Orbiter 1 running out of attitude control gas and being shut down.

The vikings had "steady state" power output from the RTG's but could do essentially nothing on RTG power alone. They'd charge up the batteries and then run on the higher current they'd provide while doing something like running the cameras and storing the data to the tape recorder. They found that in battery failure, when VL2 tried to run the tape, it went undervoltage and would safe itself. Same thing would have happened to VL1. It might have been able to call home, but not do any useful science after the batteries failed.
ljk4-1
If the MERs had landed right where the Vikings had - or if the
Vikings had been equipped with wheels instead of landing pads -
what interesting sites could they have visited?

I am particularly wondering where Viking 2 could have gone
that would be of any interest, aside from already being on Mars.
Ames
QUOTE (ljk4-1 @ Sep 26 2006, 02:34 PM) *
If the MERs had landed right where the Vikings had - or if the
Vikings had been equipped with wheels instead of landing pads -
what interesting sites could they have visited?

I am particularly wondering where Viking 2 could have gone
that would be of any interest, aside from already being on Mars.



http://www.msss.com/mars_images/moc/2005/05/05/

smile.gif
ljk4-1
QUOTE (Ames @ Sep 26 2006, 09:47 AM) *


That pretty much answers my question.

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