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Messenger En Route To Mercury
Soft writes "NASA's Messenger space probe has lifted off on its second try on a Delta 2-Heavy rocket.
As mentioned earlier on Slashdot, it is poised to orbit Mercury in 2011 after three flybys, as well as two flybys of Venus and one of Earth for course corrections.
It will be the first probe to visit the innermost planet since Mariner 10 in 1974 and 1975.
Stories on the BBC and SpaceflightNow."
Seriously, the Metric/Imperial thing happened like 1999. Since then we have had Galileo end it's mission successfully, Mars Odyssey (2001), The exploration rovers, Cassini has so far performed flawlessy, and the hard part is over (Orbit insertion), NEAR, an orbiter, landed softly on an asteroid on it's solar panels, Deep Space 1 did the comet Borrelly encounter, Stardust has successfully collected the comet material (return in 2006)..and probably others that I don't remember offhand.
I mean, after so many successes, and some folks *still* don't let go. Now, if one of the probes were lost *again* due to a measurement system error then we could get a laugh out of it, but so far...they have not done that. Granted, in 1999 the *other* Mars probe, Polar lander was lost too, and so was Deep Space 2. But still...that's five years ago, and NASA has had loads of successes since then.
This is kinda starting to resemble *BSD is dying trolls..
*and you know you got them angry when they start whining/defending "but Beagle2 was England, not ESA!" - basically admitting it was a collossal failure but trying to shift blame elsewhere (and then throwing in a US-bashing joke for good measure).
I'm not an expert, but I suspect that the problem with Mercury is that the environment is so hostile that you want to spend all your time close to the sun doing science rather than getting into orbit. This craft is going to swing by Mercury a few times, but it also swings out again, so until final orbital insertion it is generally quite far from the planet. With an ion drive you'd slowly spiral in towards the sun from Earth, so you'd spend a lot of time near the sun but not yet at Mercury.
You might also still need to carry some fuel for orbital insertion. As you approach the planet its gravity accelerates you. If you don't dump your velocity quickly, you'll slingshot away again. I suppose you could potentially get yourself into a really big orbit and then slowly lower it, though, so maybe you don't need the rocket, but again, a bunch more time spent lowering your orbit to something useful.
I think the main problem, though, is that ion engines are still considered experimental. We understand rockets. If you were chief scientist on one of these once-in-a-lifetime missions which would you rather use... an ion engine, which has only been tested in space a few times, or a rocket, which we have tested dozens of times? If you were Congress funding a $400 million mission, which would you choose? Ion engines will continue to get tested on cheap, not too important missions for a long time before anyone considers using them for the important and/or expensive stuff.
The mission planners may well have some other objectives in mind. It might be nice to have data from other angles/distances and maybe some shots of Venus, as well, especially from inside it's orbit. Ultimately, though, there is simply no huge rush to collect data on Mercury, since we aren't planning on landing people there in the near future, so you might as well cut some fuel costs.
By the way, check out the drawings of the probe. It's pretty cool looking. It's got a big radiation shield on the side it turns to the sun, and the solar panels are actually cooled. It reminds me of the research station in Homeworld