The end of MESSENGER's mission, What happens after March 2013? Options

[Seryddwr]

I know nothing about either the technological constraints or the funding possibilities, but I was wondering if anyone knew what might happen to the probe once the extended mission at Mercury comes to an end. Is it definitely going to be decommissioned? Or is there a chance of sending it somewhere else? Is there sufficient propellant to allow it to break orbit using the LVA, and (say) conduct a flyby of an Aten or Apollo asteroid? I do not know how much delta-v would be required to do this, or even if there are any targets in favourable positions, but it would (to my untrained eye) be an excellent reuse of what has proven itself to be a very capable spacecraft.

[jasedm]

No chance of Messenger spiralling sunwards I suppose, and snapping some solar limb movies on the way in ???

[JRehling]

Moving into a gravity well is just as hard as getting out.

You've all seen those spiral wishing wells for coins:

http://farm4.static.flickr.com/3449/328365...e235f0e17_o.jpg

Moving in or out of a gravity well requires propulsion in proportion to the local slope, which gets steepest at the center. A minimum-energy trajectory from Uranus to Neptune would require little impulse. Going from Mercury to the Sun would require more propulsion than any other two-body cruise in the solar system. Going from Earth to the Sun would require more energy than from the Earth to any other object in the universe. (Of course, a cruise from Earth to another galaxy would take a long TIME, but not as much energy as a cruise to the Sun.)

This is a key reason why it took so long to follow up on Mariner 10 and why Messenger utilized so many gravity assists.

Moreover, there's nothing much that Messenger could do in solar observation that a much bigger earthbound telescope can't do better from three times further away.

Finally, the planet itself has a nontrivial escape velocity. It's only slightly less than Mars's.

There's one intriguing science target left for Messenger, and that's Mercury itself.