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NASA's Phoenix Mars Lander Killed By Ice
coondoggie writes "NASA officially ended its Phoenix Mars Lander operation today after a new image of the machine showed severe ice damage to its solar panels, and repeated attempts to contact the spacecraft had failed. 'Apparent changes in the shadows cast by the lander are consistent with predictions of how Phoenix could be damaged by harsh winter conditions. It was anticipated that the weight of a carbon-dioxide ice buildup could bend or break the lander's solar panels. [Michael Mellon of the University of Colorado] calculated hundreds of pounds of ice probably coated the lander in mid-winter.'"
Remember that the lander was not meant to last through the Martian winter, and in fact was only tasked with a three month long mission. It lasted five months, which was longer than expected. The newer rovers are supposed to be able to survive for much longer, but this mission accomplished all that it was supposed to.
Destroying one of our rovers is a hostile act!
I feel your pain. It destroyed a Boeing 777 a couple of years ago.
http://michaelsmith.id.au
It was a re-do of the Mars Polar Lander. (Failed due to an un-debounced landing sensor switch).
Phoenix rose from the ashes of MPL.
--Carlos V.
Of course, an RTG would mass much more than solar power so every part of the system would have to be beefed up. Launcher, cruise stage, aerobraking. Before you know it you are paying for two missions when one at that location was all you needed.
http://michaelsmith.id.au
Astronomers refer to lots of things in their solid state as "ice", and almost always refer to what you would call "ice" as "water ice". And it makes plenty of sense.
The sun was down too far on the horizon to generate any useful power (or absorb heat directly) during winter.
Mars has axial tilt of 25 degrees; Earth's is 23.5 degrees or so. So there's an equivalent Arctic Circle zone where the sun's below the horizon during the worst of winter. Earth's Arctic Circle is at 66 degrees north; with slightly greater tilt, Mars' Arctic Circle will be even lower. The landing site was around 67 degrees north on Mars.
The sun would have been down long enough that no reasonable amount of batteries could have kept it warm overwinter. A RTG could - as discussed - or little RHU units (Radioactive Heater Unit - it's like a mini-RTG heat source module, with the protection but no power generation units, just designed to keep parts warm). But there was a decision made that the lander was unlikely to survive with all the overwinter issues, so they didn't bother.
Yes there is. Those temperatures have been observed on the south pole. (Read a report about a team that did stay “overnight” [= over winter]) And that doesn’t even include the windchill effect. Which can make it feel like a horrible -140C. A temperature that literally smacks you in the face so hard you fall over backwards. A temperature that lets your breath crackle and freeze before it lands on the floor. A temperature where pissing in the snow may make you impotent trough freezing the inside of your penis all the way. ;)
Yes, there you might find some dry ice... (e.g. the one that you just did breath out.)
But good luck finding it in nothing but endless planes of real actual ice.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
and either way, at 1 bar it doesn't freeze until about -78C. I don't think there are any natural places on Earth that cold.
Actually it's been down to -89C in Antarctica, so -78C is well within the extreme. But you go find it first, I'll stay inside by the fire long before that...
Live today, because you never know what tomorrow brings
Ok, I just found a page with waaaaaaaaay too much information, but I'll give you the short brief. First by the lower pressure at the poles and higher elevation of the coldest measurement stations, you might not pass the freezing point at all, it seems right on the border. Secondly, because there's so little CO2 in our athmosphere the sublimation effect is much stronger than the freezing effect, dry ice won't last even if held below the freezing point.
Live today, because you never know what tomorrow brings
The vapor pressure of 'dry' CO2 ice is larger than the partial fraction of gaseous CO2 in our atmosphere. That means that it will sublimate, even if it's below the freezing point. You have to go far below the freezing point, until you find the temperature where the vapor pressure is lower than the partial fraction.
This is why water ice will sublimate in very cold, very dry air. If the humidity is low enough, a blanket of snow will slowly disappear, even at -20 C. You can see that in the Midwest every winter.
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