why is the mars rover's lifespan 90 days

Dan DeConinck posted:

Why is the mars rover's lifespan 90 days ?

Communication sats last years, even 10+.

Pioneer is 20 years old. Doesn't it have nuclear power ?

The rover is powered by solar panels and has internal batteries. Eventually,
enough dust will collect on the panels and the batteries will stop holding
their charge well enough so that sometime after 90 "sols", there may or may
not be enough power available to keep the lander electronics warm and the
rover completely functioning. The 90-sol lifetime is a "nominal" one (that
is, the rover is designed to last that long), but it may go somewhat longer
(Pathfinder was designed for only 30 days of functionality, but lasted nearly
three times that). Another factor is sun angle, which after 90 days, becomes
less favorable for generating electrical power from the solar panels than it
is now. If the rover was RTG powered (ie: nuclear "batteries"), the power
would not be an issue, but such power generators are expensive, heavy, and not
popular with some environmentalists. Clear skies to you.

David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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"David Knisely" wrote in message ...
Dan DeConinck posted:

Why is the mars rover's lifespan 90 days ?

Communication sats last years, even 10+.

Pioneer is 20 years old. Doesn't it have nuclear power ?

The rover is powered by solar panels and has internal batteries. Eventually,
enough dust will collect on the panels and the batteries will stop holding
their charge well enough so that sometime after 90 "sols", there may or may
not be enough power available to keep the lander electronics warm and the
rover completely functioning. The 90-sol lifetime is a "nominal" one (that
is, the rover is designed to last that long), but it may go somewhat longer
(Pathfinder was designed for only 30 days of functionality, but lasted nearly
three times that). Another factor is sun angle, which after 90 days, becomes
less favorable for generating electrical power from the solar panels than it
is now. If the rover was RTG powered (ie: nuclear "batteries"), the power
would not be an issue, but such power generators are expensive, heavy, and not
popular with some environmentalists.

Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??

Rick

Hi,

Why is the mars rover's lifespan 90 days ?

Communication sats last years, even 10+.

Pioneer is 20 years old. Doesn't it have nuclear power ?

Dan

Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??

Rick


What a wonderfully crass , anally generated, truly American attitude! It
isn't here, we don't know what's there so it MUST be zilch or worthless.

Do your kind ever learn?

D

"david" wrote in message ...


Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??


What a wonderfully crass , anally generated, truly American attitude! It
isn't here, we don't know what's there so it MUST be zilch or worthless.

Do your kind ever learn?

Perhaps your British public school training is a bit wanting.

Mars' surface has been relentlessly bombarded with gamma and
high energy X-ray radiation for at least the last billion years. The
extra amount of radioactivity from a nuclear power cell would be
the literal equivalent of adding a single drop of water to an ocean.

Rick

"Rick" wrote in message
...
"David Knisely" wrote in message
...
Dan DeConinck posted:

Why is the mars rover's lifespan 90 days ?

Communication sats last years, even 10+.

Pioneer is 20 years old. Doesn't it have nuclear power ?

The rover is powered by solar panels and has internal batteries.
Eventually, enough dust will collect on the panels and the
batteries will stop holding their charge well enough so that
sometime after 90 "sols", there may or may not be enough power
available to keep the lander electronics warm and the
rover completely functioning. The 90-sol lifetime is a
"nominal" one (that is, the rover is designed to last that
long), but it may go somewhat longer (Pathfinder was designed
for only 30 days of functionality, but lasted nearly
three times that). Another factor is sun angle, which after
90 days, becomes less favorable for generating electrical
power from the solar panels than it is now. If the rover
was RTG powered (ie: nuclear "batteries"), the power
would not be an issue, but such power generators are expensive,
heavy, and not popular with some environmentalists.

Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??
Er.
It is not the use of a radioisotope based generator on Mars that is the
problem. Remember it has to get there first. Every time such generators are
used, there is a huge balancing act, between the amount of extra
casing/shielding needed to ensure (hopefully), that the generator will not
burst in the event of a launch accident, and the gain to the mission. Hence
generally, such generators are used where the probe is intended to go much
further from the Sun. Also, even with such a generator, batteries would be
needed to meet high 'instantaneous' demands (just like the solar cells,
these generators provide a slow 'trickle' of power, rather than being able
to meet massive peaks), and batteries have a limited charge/discharge life.
Given the extra weight of the generator, you'd probably be looking at having
to throw away half the instruments, to keep to the launch weight required.
You'd have a ship that would live longer, but do less...

Best Wishes

"Rick" wrote in message
...
The rover is powered by solar panels and has internal batteries.
Eventually,
enough dust will collect on the panels and the batteries will stop
holding
their charge well enough so that sometime after 90 "sols", there may or
may
not be enough power available to keep the lander electronics warm and
the
rover completely functioning. The 90-sol lifetime is a "nominal" one
(that
is, the rover is designed to last that long), but it may go somewhat
longer
(Pathfinder was designed for only 30 days of functionality, but lasted
nearly
three times that). Another factor is sun angle, which after 90 days,
becomes
less favorable for generating electrical power from the solar panels
than it
is now. If the rover was RTG powered (ie: nuclear "batteries"), the
power
would not be an issue, but such power generators are expensive, heavy,
and not
popular with some environmentalists.

Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??

No---what concerns evironmentalists are the consequences of a failed launch
and the dispersion into the earth's atmosphere of radioactive materials.

RM

No---what concerns evironmentalists are the consequences of a failed launch
and the dispersion into the earth's atmosphere of radioactive materials.

RM


And thats absolute bull**** as well.....

During the open air nuclear testing era literaly hundreds of atomic bombs and
dozen of TONS of really nastly nuclear material was blasted into the earths
atmosphere....

yet to hear greepeace tell it....one relatively small plutonium isotope
generator could end human life on earth if the rocket launching it failed.....

AND they design these things like brick ****houses...the only thing that WILL
break one open is nuclear bomb exploded next to one...and if thats the case the
generator is the least of your local worries...

AND even IFFFF one broke open...there is no significant danger unless it lands
in the back of a crowded school yard and some idiot there decided to take a
belt sander to it to create and spread the dust....

take care

Blll

"BllFs6" wrote in message ...
No---what concerns evironmentalists are the consequences of a failed launch
and the dispersion into the earth's atmosphere of radioactive materials.

RM


And thats absolute bull**** as well.....

Indeed. In fact the orbiter in the current mission is powered with
2.7g of plutonium chloride..

Rick

"Rick" wrote in message
...
"david" wrote in message
...


Good grief, it's MARS for chrissakes. Would the radiation damage
the planet's native flora and fauna??


What a wonderfully crass , anally generated, truly American attitude!
It
isn't here, we don't know what's there so it MUST be zilch or worthless.

Do your kind ever learn?

Perhaps your British public school training is a bit wanting.

Mars' surface has been relentlessly bombarded with gamma and
high energy X-ray radiation for at least the last billion years. The
extra amount of radioactivity from a nuclear power cell would be
the literal equivalent of adding a single drop of water to an ocean.

Rick


Oh, thats okay then.

I wasn't arguing the physics, just the attitude.

D