Mars Roover Curiosity already crippled before launch

On 20 Jun 2011 10:57:00 +0200, wrote:


The PU-238 RTG has problems. The roover was bound for a launch in 2008:

http://nasawatch.com/archives/2011/0....html#comments
From the report: Department of Energy officials stated that the power
degradation issue is unlikely to cause a catastrophic failure. However,
as a cautionary measure, MSL Project managers have reduced the missionÆs
performance capabilities to processing 28 rather than 74 soil and rock
samples and to traversing 4.5 kilometers rather than 20 kilometers.

For some reason, this seriously reduced capability was not highlighted
elsewhere in the report.

Remember that this is the baseline (contract required) capability.
Like Spirit and Opportunity, Curiosity will probably greatly exceed
these requirements.


You are right. But this time it has to exceed the new base 5 times just
to get the original one. For anything more you realy need a lot of hope.
We dont know how the line of decline looks. Could be bad.

The OIG report said "unexpected degradation". PU-238 half-life is 88 years.
So I expect a new type of RTG thermocouples degraded and they have no
replacement. It is in prototype phase, has 110 We (2 kW thermal) nominal
by 4 kg Pu. Btw, the RTG is 100% DoE and build by Boeing, no fault at NASA.
They hide the percentage power loss from public but the 4.5 km to 20 km
gives a hint. Probably the power for data transmission is now restricted
too. That means considerable less images to expect. Still worth launch?
Maybe.

Curiosity will be transmitting most of its data back to Earth through
MRO and Odyssey, so that's not a problem.

Brian

No, its a problem. The uplink equipment was designed to expect a reliable
power source. RTGs are the most reliable sources you can get. No moveable
parts, all solid state and DoE had over 50 years very succesfule
expierence in building this stuff. So unlike the solar MER roovers,
power was granted. You dont oversize the com system then. With enough
power they could about keep the size of the antenna and still uplink much
more data. If the power is now restricted they have to reduce the data
transmission rate. They have no time or mass budget to put a bigger dish
on the roover now.

Take a look at the wikipedia page of MSL. Even stuff from ESA and Russia
on board. It is a rolling science lab of the best planet earth could send
today. Look at the lot of cameras. It will be the most expensive multi
billion dollar Mars mission since the 1970s Vikings. It is the roover the
world was waiting for 30 years. For this groundbreaking mission DoE
delivered a "prototype" piece of nuclear **** that breaks down under its
own radiation. Any words to describe this?



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