Stardust + Deep Impact mission extensions, ...two new comet flybys approved Options

[ynyralmaen]

- Deep Impact to fly by Boethin on December 5, 2008.

- Stardust to visit Tempel 1 (DI's previous target) on February 14, 2011.

More details here:

http://stardust.jpl.nasa.gov/news/status/070703.html

[tedstryk]

Yes!!!!!!!!!! Thanks for posting that. I am glad to see that they won't squander two good spacecraft. I wonder if the light curve/rotation period of Temple-1's nucleus is pegged well enough to ensure catching the crater. I doubt it, but it would be nice. Even still, it will be interesting to see it again. While the press release statement, "It will mark the first time a comet has ever been revisited," had me screaming HALLEY FLOTILLA!, this will be the longest period of time between visits to the same comet.

I am also glad to see Deep Impact being used again. Although HRI isn't great, the spacecraft has a lot of other great instruments, and even HRI's out of focus shots are better than anything we could get of a comet's nucleus from earth.

I wonder if they will try to free Stardust's filter wheel. I remember it was never attempted because it was stuck on a convenient filter, and they didn't want to risk getting stuck on something less desirable for the Wildt-2 encounter. However, with having to have NAVCAM for the sample return mission over, it sure would be neat to try to free it.

[ElkGroveDan]

The EPOCh investigation also will use the Deep Impact spacecraft to observe several nearby bright stars, watching as the giant planets already known to be orbiting the stars pass in front of and then behind them. The collected data will be used to characterize the giant planets and to determine whether they possess rings, moons, or Earth-sized planetary companions. EPOCh's sensitivity will exceed both current ground and space-based observatory capabilities. EPOCh also will measure the mid-infrared spectrum of the Earth, providing comparative data for future efforts to study the atmospheres of extrasolar planets.

Brilliant on both counts. I'm really impressed.

[Paolo]

This is a very good new, but it also makes me wonder: is this all for this round of Discovery missions? Do they only approved extensions and no new missions?

[Alan Stern]

New mission proposals not yet fully evaluated. Decisions expected by early October.

-Alan

[Paolo]

New mission proposals not yet fully evaluated. Decisions expected by early October.

-Alan

Thanks! Nice to hear that

[edstrick]

Note there is *no* mention of imaging the Deep Impact crater in the press release. It's clear they consider rotational synchronizing on the basis of available light curve etc data too "iffy" for it to be an objective. I think they're assuming that any illuminated sub-hemisphere Stardust will observe will be as geologically diverse and interesting as the one imaged. *IF* we're lucky to be able to retarget the impact hemisphere, we get to observe changes between the 2 encounters due to mass loss and whatever at and beyond perihelion.

[nprev]

Starting to see a theme emerge here wrt Discovery missions...creative reuse/extension of available assets. I like it, and gonna blame it all on Alan!

Begs one question, though: will Discovery-class proposals be henceforth evaluated not only on their ability to satisfy primary science objectives, but also on their capability for reuse? Hopefully not, because that might impose a lot of cost/schedule/performance risk on the initial design effort that just doesn't need to be there for cost-capped missions... ...exploiting serendipity where you find it after the fact seems like a wiser strategy.

[edstrick]

"Starting to see a theme emerge here...."

Uh.. the first mission extension was Mariner 4. After the Mars flyby and data playback, Earth started to move out of the view of the fixed high-gain antenna. The spacecraft was left in as safe a mode as possible and the carrier signal monitored at sparse intervals when possible. When it came around from the far side of the sun into good communications geometry, an extended interplanetary fields-and-particles study mission was started.

They attempted to contact Mariner Venus 67 (Mariner 5) in what would have been it's extended mission, as the vehicles would have drifted into alignment on the same solar-wind sector, but they could not find it's signal. Ultimately, they found it, way off frequency and drifting in frequency, carrier wave only, amplitude variations indicating slow spacecraft roll, and TOTALLY unresponsive (as far as they could tell) to commands. So much for THAT extended mission... permanently vegetative state.

Mariner 4 finally ran out of attitude control gas, went into a slow roll, and it's transmitter was turned off.

Mariners 6 and 7 had limited extended missions, Mariner 9, all Vikings, Mariner 10 (venus/mercury), etc etc etc had extended missions, as did all responsive Surveyors and Lunar Orbiters.

[Alan Stern]

Nprev-- Thx for the vote of confidence, but the credit you offer me is undeserved. Proposal teams
form the pool of ideas. From that these two Mission of Opportunity were selected for Phase A studies.

All of that took place before my watch began in April. What we did was, after assuring ourselves both of these proposals in study had no significant flaws, was to find the resources to fund both. We did not architect the ideas. We simply leaned forward in selecting both vis an either or situation, and I think as a result, we have both reinvigorated US comet science and added to our exo-planet detection efforts as well.

-Alan

[Littlebit]

Even though it is not promised, it is time to reopen the pool on the depth and diameter of Tempel 1's crater. (providing the very ticked-off aliens don't shoot first this time...)

[Oren Iishi]

Yes!!!!!!!!!! Thanks for posting that. I am glad to see that they won't squander two good spacecraft. I wonder if the light curve/rotation period of Temple-1's nucleus is pegged well enough to ensure catching the crater. I doubt it, but it would be nice. Even still, it will be interesting to see it again. While the press release statement, "It will mark the first time a comet has ever been revisited," had me screaming HALLEY FLOTILLA!, this will be the longest period of time between visits to the same comet.

I am also glad to see Deep Impact being used again. Although HRI isn't great, the spacecraft has a lot of other great instruments, and even HRI's out of focus shots are better than anything we could get of a comet's nucleus from earth.

I wonder if they will try to free Stardust's filter wheel. I remember it was never attempted because it was stuck on a convenient filter, and they didn't want to risk getting stuck on something less desirable for the Wildt-2 encounter. However, with having to have NAVCAM for the sample return mission over, it sure would be neat to try to free it.

I would also like NASA to make an attempt to correct the filter wheel issue. My guess is that it might be too risky. I was also wondering what additional information could be obtained if they were able to fix the problem.

[edstrick]

Part of the problem is that COLOR imaging at comets is really marginal. Deep Impact did see subtle color variations related to exposures of sublimating water that were seen by the infrared spectrometer, but comet nucleii are nearly featureless as far as regular color imaging goes. You have to have high signal to noise ratio images taken with widely spaced (in wavelength) color filters for maximum spectral separation, or a true middle infrared camera, equivalent to the CRISM on Mars Recon Orbiter or the imaging infrared spectrometer on Cassini, before you can see much of anything.

[tedstryk]

The filters were well selected, such as the NH2 Emission filter and Oxygen Emission filter. The results would have been scientifically interesting.

[edstrick]

Those would image coma chemical structures. Very interesing and important, but I'm thinking more in terms of nuclear "geology"