MERs: what limits their lifetime on Mars surface?

Hello!

Reading various bits of info about Mars rovers on various sites
I haven't noticed (or missed?) any info about their life expectancy
on the Mars surface.

I'l curious to know what limits their life? Do they consume anything
like batteries charge-discharge cycles?

Is their ability to recharge batteries limited by the Mratian seasons?
In how long time the dust will cover the solar panels to such extent
that batteries could no longer be charged? Can these panels be rotated
briefly to vertical to allow the dust to fall off?

Is there any lubrication of the moving parts (especially wheels) that
is consumed over time?

What is the expected time for the dust to clog various moving parts?

Anything else?

TIA,
************************************************** ****************************
* Arie Kazachin, Israel, e-mail: *
************************************************** ****************************
NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap.

"Arie Kazachin" om wrote
in message ...
Hello!

Reading various bits of info about Mars rovers on various sites
I haven't noticed (or missed?) any info about their life expectancy
on the Mars surface.

I'l curious to know what limits their life? Do they consume anything
like batteries charge-discharge cycles?

Is their ability to recharge batteries limited by the Mratian seasons?
In how long time the dust will cover the solar panels to such extent
that batteries could no longer be charged? Can these panels be rotated
briefly to vertical to allow the dust to fall off?


Solar panels 'wear' out so the power generation drops. And the batteries
themselves also have a limited number of charge-cycles which they can handle
(same with recharcheable batteries in cell-phones etc.). The lifetime of the
electronics and moving parts is far longer, and not the limiting factor.

i have read that they are built to last 90 days. however, in the past when
they said it would work x, it has always worked 2x to 3x, so we could still
be watching them roll in late spring or early summer (earthime)

Bob

"Arie Kazachin" om wrote
in message ...
Hello!

Reading various bits of info about Mars rovers on various sites
I haven't noticed (or missed?) any info about their life expectancy
on the Mars surface.

I'l curious to know what limits their life? Do they consume anything
like batteries charge-discharge cycles?

Is their ability to recharge batteries limited by the Mratian seasons?
In how long time the dust will cover the solar panels to such extent
that batteries could no longer be charged? Can these panels be rotated
briefly to vertical to allow the dust to fall off?

Is there any lubrication of the moving parts (especially wheels) that
is consumed over time?

What is the expected time for the dust to clog various moving parts?

Anything else?

TIA,

************************************************** **************************
**
* Arie Kazachin, Israel, e-mail:
*

************************************************** **************************
**
NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM
trap.

On Fri, 9 Jan 2004 00:24:19,
(Arie Kazachin)
wrote:

Reading various bits of info about Mars rovers on various sites
I haven't noticed (or missed?) any info about their life expectancy
on the Mars surface.

90 days.

http://marsrovers.jpl.nasa.gov/mission/tl_surface.html

"Eventual End of Mission

Toward the end of the surface phase for both missions, both power and
telecom capabilities will be decreasing, as the Earth and the Sun
become more distant from Mars, dust falls on the solar panels, the
batteries lose capacity, and the Sun moves further North past the
landing site latitude. Eventually, somewhere near Sol 91 it is
expected that the rover will be unable to store up enough thermal or
battery energy to prevent its components´ overnight temperatures from
falling below flight allowable levels. That will sooner or later
result in failure of one or more of those components, silencing the
rover forever."


Someone at JPL needs to read that paragraph to the MER engineers. The
clock is ticking, folks. Get that puppy moving. No sense sending a
rover to Mars if you're too timid to drive it off the lander.

Brian

In article ,
Brian Thorn wrote:
Someone at JPL needs to read that paragraph to the MER engineers. The
clock is ticking, folks. Get that puppy moving. No sense sending a
rover to Mars if you're too timid to drive it off the lander.

The timeline has always included a few days of checkout on the lander
before driving off. The MER engineers are fully aware that the clock is
ticking, but there's lots to do. They aren't sitting around dithering.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Brian Thorn wrote:


Someone at JPL needs to read that paragraph to the MER engineers. The
clock is ticking, folks. Get that puppy moving. No sense sending a
rover to Mars if you're too timid to drive it off the lander.

I'm sure they are aware of it. But just think how much everybody
would squeal if they tip it over or get hung up because they just drove
it off forward and took their chances. It's one minor, planned-for
contingency in an otherwise close-to-flawless operation.


Brett

On Sun, 11 Jan 2004 18:10:52 GMT, (Henry Spencer)
wrote:

Someone at JPL needs to read that paragraph to the MER engineers. The
clock is ticking, folks. Get that puppy moving. No sense sending a
rover to Mars if you're too timid to drive it off the lander.

The timeline has always included a few days of checkout on the lander
before driving off. The MER engineers are fully aware that the clock is
ticking, but there's lots to do. They aren't sitting around dithering.

My main complaint is that they are reportedly "testing the turn to
drive off in another direction." Now, they going to rehearse the
maneuver and not drive off until Thursday (Sol 12, I think).

Why wasn't this tested before they got to Mars?

Brian

They say the internal temps are running a little higher than predicted, so that
would be good news for longevity, i would say... I thought on Sojourner, they
put inside little sealed plutonium or uranium capsules as solid-state heaters,
like mini RTG's withoutmhe power connections, ust to serve as 'hot water
bottles" to keep the insides warm overnight... zat true? And are any of thes
ein MER 1 and 2? Why not, if not?

(Henry Spencer) wrote in message ...
In article ,
Brian Thorn wrote:
Someone at JPL needs to read that paragraph to the MER engineers. The
clock is ticking, folks. Get that puppy moving. No sense sending a
rover to Mars if you're too timid to drive it off the lander.

The timeline has always included a few days of checkout on the lander
before driving off. The MER engineers are fully aware that the clock is
ticking, but there's lots to do. They aren't sitting around dithering.

Assuming all systems check out o.k. and the rover drives off into the
Martian sunset towards the distant hills in one direction, what is the
maximum possible range we can expect it to cover in the remaining 80
or so Sols of primary mission left?

Does JPL have any kind of 'range coverage' ambitions in mind or is it
all about geology and water search around the locale of the landing
site? My own wish would be to go for some exotic, elevated terrain
which is *different* to the Viking 1, 2 and MPF type open-field
scenes, which would be essentially repeat playbacks with no *new*
exposures in this mission.

AA

In article ,
MSu1049321 wrote:
...I thought on Sojourner, they
put inside little sealed plutonium or uranium capsules as solid-state heaters,
like mini RTG's withoutmhe power connections, ust to serve as 'hot water
bottles" to keep the insides warm overnight... zat true?

Yep. They're called RHUs, Radioisotope Heating Units. They use Pu-238,
just like RTGs although in rather smaller quantities. The one snag is
that you can't turn them on and off, so you have to go easy with them to
avoid overheating.

And are any of these in MER 1 and 2?

Yes.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |