Re: Cassini-Huygens Mission status report

From: Henry Spencer (henry_at_spsystems.net)
Date: 06/13/04 

Date: Sun, 13 Jun 2004 16:45:53 GMT

In article <6eb47d23.0406122115.297de041@posting.google.com>,
Duncan Young <smudog@mac.com> wrote:
>> But there are lots of other low-hanging fruit remaining, as witness all
>> the rejected Discovery proposals.
>
>There were reasons why those missions got rejected - some more than others.

*Some* of them certainly had problems, or were pushing things too hard.
Others were perfectly reasonable missions which simply didn't make the cut.

>> The Moon remains poorly mapped in several important ways, e.g. we still
>> do not have good topographic maps of the poles or gravity maps of the
>> farside.
>
>True - but the moon now has its own entire Office outside of
>Discovery.

And it could be back in Discovery a year from now. But what relevance has
that to the topic? The issue at hand is that there is still significant
work that could be done there at relatively low cost. Which office it's
run from is irrelevant.

>> I predict that we're going to find out that comets, like asteroids, are
>> much more diverse than we'd thought. We've barely scratched the surface
>> of what can be done with low-cost missions to them.
>
>And its a damn shame about CONTOUR. A tightly-proscribed program like
>Discovery might not be the best program for investigating diversity.

The big problem with Discovery for that is that it's not really a
"program", just a random grab-bag of missions, whoever did the best sales
pitch last year. For properly investigating diverse objects, you want a
series of similar spacecraft, and there's no home for that in Discovery.
(In fact, there isn't really a comfortable home for that anywhere in NASA.
Even the Mars program, which really is a *program* to some extent, finds
it difficult to just repeat a successful mission, even when that would be
scientifically a very interesting thing to do.)

>> It's not unthinkable to do non-RTG missions to Jupiter in particular...
>
>It seems to me that propulsion requirements for entering Jupiter orbit
>and DSN support issues limit what you can do with non-nuclear power at
>Jupiter, especially when you include the mission duration constraints
>of Discovery.

Some of this is a matter of artificial limitations of Discovery, rather
than inherent difficulties of doing low-cost missions. The DSN issue
definitely is a bad one, though.

>> Cheaply landing on Mercury or Venus is pretty hard. But there are plenty
>> of more-accessible unexplored bodies in the inner solar system.
>
>Again, Moon and Mars have their own offices.

I wasn't thinking of either one. And again, I'm talking about missions,
not about bureaucratic turf.

>> Finally, let us not forget that if you're willing to limit yourself to
>> carefully-chosen objectives in the inner solar system, there are people in
>> several places who think they could give you a sizable program of unmanned
>> missions for the cost of one Discovery mission. There's no inherent
>> reason why planetary missions have to cost hundreds of millions each.
>
>Beagle 2 and Deep Space 2 remain counterpoints.

Note the words "carefully-chosen objectives". If you insist that the
objective has to be a Mars landing, and you have no tolerance for failure
so the hardware has to work the first time, that does make for an
expensive mission which can't be slimmed down below a certain point. 

-- 
"Think outside the box -- the box isn't our friend."    |   Henry Spencer
                                -- George Herbert       | henry@spsystems.net

Relevant Pages

  • Discovery@15 - Looking Back, Moving Forward
    ... "PI-led" missions of both directing the science effort and being ... Hosted by NASA's Planetary Science Division and the Discovery Program ...
    (sci.space.news)
  • Re: Messenger - long way to Mercury?
    ... > henry@spsystems.net (Henry Spencer) writes: ... Isnt' that part of the discovery missions goals? ... a bit like Discovery but with bigger budgets, ...
    (sci.space.history)
  • Re: Cassini-Huygens Mission status report
    ... >>asteroid mission, the moon mapper, the comet probe, the IPM sample ... There were reasons why those missions got rejected - some more than ... Well, it was a joke, but witness DAWN - an extremely extended ... Discovery, unless you are content with flybys. ...
    (sci.space.history)
  • Re: Messenger - long way to Mercury?
    ... Isnt' that part of the discovery missions goals? ... Discovery. ... half-hearted attempt to encourage proposals to include some technology ...
    (sci.space.history)