Veteran NASA probe Dawn: Winter is coming on Ceres (sort of)

There is icy activity on the surface of dwarf planet Ceres, according to researchers studying observations from NASA’s probe, Dawn. In news that will intrigue scientists and leave fans of science fiction series The Expanse* positively giddy with excitement, there is a sort-of weather system on Ceres resulting in ongoing …

[paulej72]

Orbit change without fuel

If the change to 50x4000 orbit will exhaust the fuel, how will the probe circularize its orbit at the end of its life?

[cray74]

Negative Reactions

Kepler, Dawn, Hubble, Hayabusa, ROSAT, and others have been hampered or outright ended by reaction wheel failures. What are the common failure sources of the reaction wheels, frictional/wear related?

[Ugotta B. Kiddingme]

Re: Negative Reactions

"What are the common failure sources of the reaction wheels, frictional/wear related?"

an older answer to your question, but presumably still valid and interesting.

[Stoneshop]

Winter is coming

Have you gotten your HBO notice yet?

[Anonymous Coward]

Re: Winter is coming

Surely prior art was established centuries ago with "Summer is icummen in" and those skilled in the art will readily see that this can be applied to a plurality of other seasons including, but not limited to, winter

[Ugotta B. Kiddingme]

The Expanse

If you aren't familiar with this series, I HIGHLY recommend it. One of the very few that tries to get the physics of life/travel in space correct without resorting to technobabble and exotic theories*. It's one of the few shows SyFy channel got right.

* NOT including one of the key plot points which I won't spoil. Strictly speaking of how the show addresses working/living/travelling in space.

[Anonymous Coward]

Re: The Expanse

I'd actually rather recommend the books. The T.V.-series - while good - pales in comparison.

[Mark 85]

Another extended mission coming to an end?

Pity that we don't think ahead some more and give them more fuel. I realize reaction wheels can get very expensive and heavy but the cheap route is just to load in more fuel.

Disclaimer, I realize not every explorer type of satellite will have it's mission extended but maybe should provide for that option.

[A K Stiles]

Re: Another extended mission coming to an end?

but more fuel means bigger tanks and more fuel required to get to the destination - it's all a bit Zeno's paradox with diminishing returns for your money.

[ThatOne]

Or carry a spare wheel? In the trunk?

[Francis Boyle]

Or if you want to wait

just nick one from Starman. I don't think he's really using them.

[cray74]

Or carry a spare wheel? In the trunk?

That's common actually. Three wheels are needed for all-axis control, but four are typically included in the design.