Re: Mars Rover Windshield Wiper

"Jeff Findley" <jeff.findley@xxxxxxxxxxxxxx> wrote:

"John Crichton" <crichton@xxxxxxxx> wrote in message
news:mpysi.32477$Xa3.11494@xxxxxxxxxxxx
The real answer is to dump the solar cells and use radioisotope thermal
generators (RTGs). The viking landers used them and of course all of the
deep space probes (pioneer, voyager, etc) must use them due to the great
distances from the sun they are required to operate at. RTGs have become
politically incorrect for completely unscientific reasons.

Unfortunately, they also cost more in a project than solar panels.

They are also considerably heavier, and considerably hotter (in
temperature).

For the Mars polar landers to me it is not debatable. If solar powered
they are guaranteed to have a short life since the electronics *will* lose
power during the Martian winter and the extreme cold *will* kill them.

You seem awfully sure that the cold will completely kill these landers.
Why? I could see them getting covered in ice/now/whatever as the pole
freezes during winter, but why wouldn't it be possible for them to power
down during the winter and wake in the spring after solar power has
returned?

Because we don't have a battery that can hold sufficient charge across
the winter - and because it's awfully hard to design electronics that
will power down into a deterministic state that will power up reliably
when the solar panels are illuminated again in the spring. Then there
is the (AIUI) high probability of damage caused by differential
contraction as the lander cools.

D.
--
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
.

Relevant Pages

  • Re: Mars Rover Windshield Wiper
    ... The viking landers used them and of course all of the deep space probes must use them due to the great distances from the sun they are required to operate at. ... RTGs have become politically incorrect for completely unscientific reasons. ... they are guaranteed to have a short life since the electronics *will* lose power during the Martian winter and the extreme cold *will* kill them. ... I could see them getting covered in ice/now/whatever as the pole freezes during winter, but why wouldn't it be possible for them to power down during the winter and wake in the spring after solar power has returned? ...
    (sci.space.shuttle)
  • Re: Mars Rover Windshield Wiper
    ... generators (RTGs). ... The viking landers used them and of course all of the ... power during the Martian winter and the extreme cold *will* kill them. ...
    (sci.space.shuttle)
  • Re: On Topic Tuesday: The Looming [...] Shortage
    ... which basic materials run out, ... RTGs from and 10 of them are going to Mars. ... massively incompetent but because when it comes to outer planet probes, ... he had the nations of Earth and space run their power ...
    (rec.arts.sf.written)
  • Re: EV2?
    ... suggests the RTGs on Voyager were 37.69 kg, so if it is a linear ... although total electrical power output is low. ... If the isotopes were heating _air_, then the heated air could be used to drive some sort of electrical generator - like a Sterling cycle system or steam generator - with the isotopes replacing the heat source that would be normally be supplied by solar heating or combustion. ... Why can't you use the 'loose electrons' in plutonium as electron flow in a battery in place of lithium or other chemicals. ...
    (sci.space.policy)
  • Re: EV2?
    ... suggests the RTGs on Voyager were 37.69 kg, so if it is a linear ... although total electrical power output is low. ... If the isotopes were heating _air_, then the heated air could be used to drive some sort of electrical generator - like a Sterling cycle system or steam generator - with the isotopes replacing the heat source that would be normally be supplied by solar heating or combustion. ... Even if you could get it made at a lower cost, the total weight of isotopes needed to replace all motors on cars, trucks, and trains throughout the world would imply a world running entirely on nuclear fission electrical power generated by breeder reactors, and when you kick things up to that level the radioactive ores are going to run out in fairly short order. ...
    (sci.space.policy)