Thursday, June 16, 2005

OPAG Meeting Part II: New Horizons 2

One of the items discussed at the OPAG meeting in Boulder was the proposed New Horizons 2 mission. This mission would use a clone of the New Horizons spacecraft, a mission is preparation for a Pluto/Charon flyby as well as a pass by a smaller Kuiper Belt object. New Horizons 2, if launched in 2008 or 2009, would flyby Jupiter and Uranus on its way to a large KBO. The Uranus aspect is time critical given its setting during the Uranian equinox. This would provide excellent global coverage of Uranus' mid-sized icy satellites (like the oddity Miranda), as well as study Uranus' magnetosphere and atmosphere at this juncture.

For more in-depth information on this proposal, check out a power point file over at the New Horizons website.

From my understanding, the reaction to the proposal was mixed. The issue came down to the lack of ability to propose a New Frontiers mission outside of the 5 recommendations in the Decadal Survey. This certainly needs to be changed if new discoveries or targets of opportunity (like a flyby of Uranus at equinox) are found.


Anonymous JRehling said...

This is a very good, if not great, candidate mission, and if it is buried, that will illustrate some flaws in the mission selection process.

Fundamentally, there are numerous top-down constraints imposed upon mission selection now, well-meant, but they only rob the agency of some potential value.

Preconceptions concerning what the target should be punish precisely the kind of mission NH2 would be (returning science from Jupiter, Uranus, and a KBO -- an unlikely trio).

A better formula than the present set of arrangements is to post a "bounty" for all imaginable science goals, and select missions based upon their science/dollar (count risk assessment, too). By definition, any deviation from this method means less science for your budget.

I don't know where NH2 would rank among all possible missions, but it is going to compete at a disadvantage because of institutional top-down constraints that rob the agency of science returned per dollar.

6/16/2005 05:44:00 PM  
Blogger Bruce Moomaw said...

I continue to be queasy about NH 2 (a fact which distresses Alan Stern, who had hoped to make me into a wild-eyed cheerleader again). $500 million is still a hell of a lot of money at a time when NASA's science budget is seriously pinched -- and, when you get down to it, absolutely the only thing NH 2 could do that some other, modestly later composite mission couldn't is its equinoctial view of Uranus and its moons. Scientifically useful, yes -- but worth all that money at this time?

What kind of alternative "composite missions" am I talking about? Well, the new Solar System Roadmap currently plans to make a Neptune orbiter with entry probes one of 3 to 5 alternative choices for a really big (possibly multi-billion dollar) Solar System mission in the 2025-35 period. I've been pushing, as a possible alternative, a Neptune flyby with entry probes, which might not cost much more than a New Frontiers mission (maybe $800-900 billion). This would have an excellent chance of flying in this period (or earlier) if the Neptune orbiter isn't picked for that period; it would make the Neptune orbiter itself a good deal easier by removing the entry probes (which, given the plan to aerocapture the orbiter into orbit around Neptune, would have to be later ejected by it from a HIGH orbit around Neptune); it could still give us one close flyby of Triton (these are one of the orbiter's main goals); it could probably emulate NH 2's plan to fly by a really big pre-chosen KBO; it might very well be able to also fly by a Trojan asteroid and/or a Centaur object (which, together, are regarded as justifying a NF mission of their own during this period); or -- if it passed up the Trojan flyby -- it could make a gravity-assist flyby of Jupiter which might also give it a chance for a really close flyby of Io.

Alternatively, however, we might aim such a fairly near-term flyby/entry probe mission not at Neptune but at Uranus. All the Neptune flyby mission's positive points apply to this one, except that it wouldn't be able to make a close flyby of any moon as big and interesting as Triton. That is: for just a few hundred million more than NH 2, it would also be able to give us our first entry-probe look at an ice-giant planet, which is considered very important whether the planet in question is Neptune OR Uranus; and if properly planned and timed, it could also do any of the other possible things which the Neptune flyby/probe mission could do (flybys of a Centaur, and of a Trojan or Io) that NH 2 can't because of its timing and mission design. It would also allow the Neptune Orbiter to not duplicate a target -- and that Orbiter would still likely be scientifically worthwhile whether it carried Neptune entry probes or not. Finally, if we launched it early enough, it would still be able to get a good look at Uranus at about the midway point between the planet's equinox and solstice. And, of course, it would arrive at Uranus sooner than it would have at Neptune, and its chances of failing en route would be mildly reduced.

So: as I say, I just cannot build up any big head of enthusiastic steam for NH 2 -- although I also can't present any really condemnatory case against it. In any case, I await the coming reports on the NH 2 mission mentioned on the last page of the new OPAG report.

6/16/2005 11:50:00 PM  
Blogger Bruce Moomaw said...

"...which might not cost much more than a New Frontiers mission (maybe $800-900 billion)."

That's "$800-900 MILLION". Oy.

6/16/2005 11:51:00 PM  
Anonymous Anonymous said...


I'm with Bruce on this one. I'd love to see a solid mission to one of the ice giants, but NH2 isn't optimized for those targets. You really want a microwave instrument to probe the deep interior and/or an entry probe (ideally both, since they answer different questions).

The fair way to view this is if NASA has a spare $400M for planetary studies, what is the highest priority purchase it can make for that money. Ideally, NH2 should be allowed to compete in the Discovery 12 competition (which would require a waver for the nuclear power source). That would allow a competition for the best mission for about this amount of money.

6/18/2005 12:00:00 AM  
Blogger Bruce Moomaw said...

Now, THAT'S an idea -- especially since NASA will be raising the cost cap for the next Discovery AO to $450 million.

6/18/2005 02:05:00 PM  
Blogger Bruce Moomaw said...

The presentations from the June OPAG meeting are now online:

Perhaps the most interesting are the two on the new design of the Europa
Orbiter. This work is now very advanced and detailed, and the science
payload has been greatly enlarged from the earlier design -- although it
still seems questionable that a small lander could be added. (They may also
be aiming for a launch as early as 2012.)

However, most of the others are also of note. Note in particular the piece
about work on two possible Titan mission designs -- one of which consists
not of an aerobot, but of a small surface rover with inflatable wheels,
which might be able to drive 500 km in 3 years. (The other, oddly enough,
is simply a Titan orbiter -- no aerobot mission design is presented here,
although it's very unlikely that the concept has been rejected.)

6/29/2005 02:29:00 AM  

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