# Tell me about space probes **URL:** \ **Category:** Factual Questions\ **Created:** [January 11, 2004, 4:17pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999 "2004-01-11T16:17:03Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Freejack00](https://avatars.discourse-cdn.com/v4/letter/f/b9e5f3/32.png) [@Freejack00](https://boards.straightdope.com/u/Freejack00)\ **Post date:** [January 11, 2004, 4:17pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/1 "2004-01-11T16:17:03Z")
I’ve always had the curiosity and have never heard much about what happens to a space probe that leads to it’s demise.Say it lands on Mars…after a few weeks or months the signal disappears.Do the bateries run out? Doesn’t it run on solar energy? Why do systems shut down so soon while I have read that other space probes such as Viking last for years? The Pathfinder only ran for a couple of months.😕 Thanks in advance ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [January 11, 2004, 4:46pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/2 "2004-01-11T16:46:03Z")
temperature and atmosphere also contribute to their destruction. ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [January 11, 2004, 5:02pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/3 "2004-01-11T17:02:26Z")
The Mars Rovers have solar panels, and also rechargeable batteries (to provide energy when the Sun isn’t shining). Some problems with the power sources (from the [Mars Exploration Rovers Website](http://marsrovers.jpl.nasa.gov/mission/spacecraft_rover_energy.html)): > [@](#): > > Over time, the batteries will degrade and will not be able to recharge to full power capacity. Also, by the end of the 90-sol mission, the capability of the solar arrays to generate power will likely be reduced to about 50 watts of power due to anticipated dust coverage on the solar arrays (as seen on Sojourner/Mars Pathfinder), as well as the change in season. Mars will drift farther from the sun as it continues on its yearly elliptical orbit, and because of the distance, the sun will not shine as brightly onto the solar arrays. Additionally, Mars is tilted on its axis just like Earth is, giving Mars seasonal changes. Later in the mission, the seasonal changes at the landing site and the lower position of the Sun in the sky at noon than in the beginning of the mission will mean less energy on the solar panels. Deep space probes (like the Pioneers and Voyagers) are powered by the heat-generating breakdown of radioactive isotopes, and this radioactive fuel is eventually used up, causing the probes to fade away. ---
**Author:** ![Freejack00](https://avatars.discourse-cdn.com/v4/letter/f/b9e5f3/32.png) [@Freejack00](https://boards.straightdope.com/u/Freejack00)\ **Post date:** [January 11, 2004, 5:36pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/4 "2004-01-11T17:36:00Z")
Thanks Buckner… I never considered the “dust” on the panels or the season’s.The use of radioactive isoptopes on deep space probes is also interesting…Thank you for clearing it up!! ---
**Author:** ![sibyl](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@sibyl](https://boards.straightdope.com/u/sibyl)\ **Post date:** [January 11, 2004, 5:40pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/5 "2004-01-11T17:40:41Z")
Couldn’t they have installed some sort of wiper on the solar panels to wipe the dust off? ---
**Author:** ![duffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duffer/32/1026_2.png) [@duffer](https://boards.straightdope.com/u/duffer)\ **Post date:** [January 11, 2004, 6:00pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/6 "2004-01-11T18:00:29Z")
That was my first thought, sibyl. Also, why not send it to the “equator”? ---
**Author:** ![ZebraShaSha](https://avatars.discourse-cdn.com/v4/letter/z/eada6e/32.png) [@ZebraShaSha](https://boards.straightdope.com/u/ZebraShaSha)\ **Post date:** [January 11, 2004, 6:24pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/7 "2004-01-11T18:24:45Z")
I have always heard that if the probe does not have a flanged base then it will be sucked up by Uranus. ---
**Author:** ![Freejack00](https://avatars.discourse-cdn.com/v4/letter/f/b9e5f3/32.png) [@Freejack00](https://boards.straightdope.com/u/Freejack00)\ **Post date:** [January 11, 2004, 7:20pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/8 "2004-01-11T19:20:15Z")
> [@](#): > > \*Originally posted by duffer \* > \*\*That was my first thought, sibyl. Also, why not send it to the “equator”? \*\* Good point…!!!😃 ---
**Author:** ![Ficer67](https://avatars.discourse-cdn.com/v4/letter/f/c57346/32.png) [@Ficer67](https://boards.straightdope.com/u/Ficer67)\ **Post date:** [January 11, 2004, 8:08pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/9 "2004-01-11T20:08:33Z")
They do send them to the equatorial regions of mars. There was a NOVA Special detailing the entire project on last night. It shouldn’t be that much of an issue to put a blower on the panels, except that everything has to fold up to fit inside the lander module, and such things may have gotten in the way. Also, the project engineers and physicist are on such a tight budget that the time required to design such a thing, and the money to build it could put them over budget. I will try to find a link to that special. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [January 11, 2004, 9:54pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/10 "2004-01-11T21:54:42Z")
I’ve wondered that myself. On the whole, there’s not a lot that can really go wrong with those things other than the power supply. I was just reading about this type of thing last week. If you go to the Pathfinder web pages, you can read the last (relevent) [news entry](http://marsprogram.jpl.nasa.gov/MPF/newspio/mpf/status/pf971029.html). The main battery failed (to be expected in the conditions), leading to a large temperature drop after the heaters stopped working (I assume due to the battery problem, I dunno). You can read the rest there. In addition, [solar panels](http://www.solaraccess.com/news/story?storyid=5834) on mars get slowly covered with dust, drastically reducing their efficiancy. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 11, 2004, 10:16pm UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/11 "2004-01-11T22:16:00Z")
As for why not wipers - because you draw the line somewhere. There are a number of components that fail on a rover over time. Sure, you might be able to increase the life of the panels, but then you just run up against some other mission-limiting problem. In the meantime, you’ve made the rover heavier, more complex, more expensive, etc. In any event, you don’t do engineering like that. You don’t say, “What can we do to keep the rover alive as long as we can?” Not in a device that has to be optimized as highly as a rover is. You start from the requirements. What do we want to accomplish on this mission? How much time do we have to build it? How much can it weigh? How much money do we have? From those requirements, you put together a list of proposed experiments, and the equipment you need to do it. Then you design a rover that can stay alive long enough to achieve those measurements. If it lives longer than that, it’s a bonus. But the design lifespan is going to be whatever it takes to accomplish the tasks you’ve set out. So you’ve got a Mossbaur spectrometer. You’ve got a rock abrasion device. A thermal imaging camera. A few other cool instruments. You lay out a plan for your experiments. Then you design the machine to carry it out. In the past, missions have failed because they’ve become a giant wishlist for everything. ‘Feature Creep’ is the #1 killer of engineering projects. Each little feature may cost very little, but once you start letting them in, it turns out that everyone has a little improvement, a cool idea for making something a little better, etc. They all sound good in and of themselves. But once you start adding them to a design, you generally find that everything goes to hell pretty quickly. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 12, 2004, 12:38am UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/12 "2004-01-12T00:38:54Z")
> [@](#): > > \*Originally posted by Sam Stone \* > ‘Feature Creep’ is the #1 killer of engineering projects. From Russian Admiral Sergei Gorshkov: _‘Best’ is the enemy of ‘good enough’_ ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [January 12, 2004, 1:22am UTC](https://boards.straightdope.com/t/tell-me-about-space-probes/223999/13 "2004-01-12T01:22:32Z")
They also have a problem with those pesky Martians sneaking up and turning them off. “Dol-burn rover’s gettin’ its tracks all in my ice farm. This’ll learn 'em.”