Quercus wrote:geekguyandy wrote:speising wrote:why didn't they put an RTG into the lander? that would have provided energy for years.
They addressed this in one of the press briefings. They said it was a political hurdle they could not cross.
Urgh, if it was an engineering problem I'd be okay with it, but politics, blargh!
Pu-238 is the main isotope used for RTG's and nobody's making it; the US and Russia are running low (apparently NASA get there's from the Russians) and the ESA probably doesn't have easy access to any.
And Philae's expected mission duration is short; is it worth the effort of using such a heavy power source (aren't they around 50kg or something?) when it's not going to actively be used for long?
(Not to mention some people were upset with the Cassini launch due to its use of an RTG, but let's ignore them).
peregrine_crow wrote:So why don't they do a full test of all crucial systems inside a vacuum chamber before sending it on a decade long mission? Just to make sure something like this doesn't happen ten years down the line.
Do we not have vacuum chambers that large (I have no idea how large Philea is, but it can't be that big, right)?
The lander is 1 x 1 x 0.8 m and weighs about 100kg.
But probably nobody thought it necessary; the chemistry looked fine and you do get a reaction when you try to burn nitrocellulose in vacuum (it just doesn't explode).