The detection of new Near Earth Asteroids (NEOs) continues at a rapid pace, a pace which will increase upon completion of the LSST in 2015. The number of NEOs known has at least doubled, perhaps tripled, since 2003. (cite needed, empirical evidence supplied below)
What I have in mind is a series of small spacecraft, say, 4-12 in number, that would each visit 3 asteroids or comets over a 4-6 year period of life. The tour is only "grand" in that we could explore nearly every known asteroid classification, and would probably be considerably cheaper in current dollars than Voyager 1 and 2 were, particularly if a new launcher like the Falcon 1 or 9 was used.
I haven't the foggiest idea how to generate the enthusiasm for this idea, or the funding, aside from writing about it, and... perhaps... since my stock in trade is as a software engineer, maybe I could work towards making broadly available the software for calculating possible courses (trajectories). Perhaps being able to plot a real course for Cruithne, or tens of thousands of other small bodies, like Sulu from Star Trek, would get more people interested and involved. I know the simulations that Bruce Damer did of the Mars Rover were wildly popular, particularly among youth.
All I really know (thus far) about re-solving this problem is from a chat with one of the scientists involved (items in bold are my open questions, italics is what he told me):
The trajectory code used for that analysis was JPL's Midas patched conic trajectory tool.(how does a US citizen get access to Midas? The conic section tool appears to be a commercial product from JPL. Is there an alternative? Is it even necessary?) The tool was automated to run 1000's of combinations of solutions. (How? What happened to the code?) These solutions were reduced using impulsive delta-V as a primary FOM. (OK, that's the easy part) The solutions that filtered to the top were then run through a low thrust trajectory code, segment by segment, to generate a end-to-end low thrust trajectory profile. (Solar-Electric propulsion makes a lot of sense, but old fashioned chemical propulsion might be more sustainable for in-situ refueling, being able to simulate a wider variety of spacecraft (included manned ones) would be useful)
Unfortunately it was rather labor intensive process and the work did not continue. Sigh.
It has taken me a long time to get interested in space again, ever since Trailblazerbecame ashes over the Pacific. What is making me think about it is that orbit@home is now up and running, and there is an amazingly powerful n-body code out there for CUDA , as well. Perhaps this would make it possible to solve a "New Grand Tour" problem for large numbers of asteroid and comet targets using differing types of spacecraft. For all I know, a 200 dollar card with CUDA and suitable software may well be more powerful than the compute clusters used during the development of Hera. (see left for a lovely example simulation of whole galaxies in collision - surely something like that ought to be able to help plot a few courses in our piddly little solar system?)
In terms of delta-v: there are presently 952 good reasons to go to the asteroids rather than the Moon. Some delta-v reasons are almost twice as good than the moon option.
It's also worth repeating the Deep Impact or Don Quijote missions 3756 times by the same criteria....
PS: I note that estimated delta-v via shoemakers method is not a particularly good criterion for justifying asteroid missions over Moon and Mars missions, but it may provide a good starting point for a conversation over the resources required to explore the solar system.
PPS: I really don't want to explain delta-v, please see wikipedia for delta-v, interplanetary superhighway, etc....
I would really like to see the above chart updated, but given what we know know about the solar system, vs what we knew in 1996, it would be all orange and red inside of Jupiter's orbit, on the scale at which the objects are plotted.