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Posted by: Del Palmer Aug 30 2007, 03:57 PM

Anyone have any information/speculation on when such a balloon might fly?

http://www.jpl.nasa.gov/news/features.cfm?feature=1448

Posted by: elakdawalla Aug 30 2007, 04:40 PM

The Venus community would love to see a balloon-equipped "Venus In Situ Explorer" as the next New Frontiers mission. The problem is that Venus keeps getting nicked on technology readiness -- basically, anything else you can propose to do with a New Frontiers mission will be closer to something that has been done by NASA before than a Venus balloon, so it's hard to see how it will win the competition. You can see various discussions of this in my notes from the http://www.planetary.org/blog/article/00000039/ and http:///news/2006/0502_Reports_from_the_May_12_2006_Meeting.html.

Cool photo, thanks for posting the link!

--Emily

Posted by: gndonald Aug 31 2007, 03:56 PM

Interesting article, I hope that this proposal has better luck than the one NASA http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690006258_1969006258.pdf(23mb) back in the late 1960's.

Posted by: rlorenz Sep 1 2007, 01:08 PM

This particular incarnation is Kevin Baines' VALOR Discovery mission proposal, which
was submitted to the last round but not selected.. Kevin told me the other week that in
fact they weren't dinged too badly on the technology readiness but were hit (unfairly)
on other factors.

Disco is such a crapshoot.

But anyway, there are Venus balloon concepts out there which are less elaborate than
the New Frontiers class ideas that Emily mentions.

Something I have observed (in thinking about Titan) is that no planetary balloon has flown
(VEGA) or even got close to flying (Mars 96) as the sole element of a mission. Somehow
the science value vs risk tradeoff never seems to work. A 'politically viable' balloon IMHO has to be
an add-on, part of a broader scientific architecture (such that if the balloon tanks, the whole
mission isnt seen to fail), and quite possibly justified on technology development and outreach
grounds rather than purely scientific ones. Hence VEGAs were drop-offs with landers en route to
Halley, and Mars-96 balloon was part of a small armada of small landers, penetrators etc.

Jaques Blamont last week at Europlanet disagreed with me of course, but I contend that
often the case that science carried on balloons is important and/or has to be done from a
balloon (rather than from a platform whose perceived risk is lower, whatever the real
risks happen to be) is not well made.

Posted by: nprev Sep 1 2007, 05:24 PM

Hmm. Projectitis rears its head yet again; interesting to see that it's not confined to the US DoD.

Maybe the balloon proposal would fare better if the platform itself multitasks to the highest possible degree. Chemical analysis of the atmosphere at various levels is obviously the most desirable data that could be obtained, as well as meteorology. Would a hi-res (cm resolution) surface radar imager add significant scientific value? You'd get swaths al a Cassini, but all the time...

Posted by: rlorenz Sep 2 2007, 01:28 PM

First remember that most balloons cannot traverse large altitude ranges - maybe a scale height or
two at most. And even to do that you need clever ballasting like condensing vapor a la ALICE experiment
from JPL, or a Montgolfiere that you can control the heat to. So that's a lot of vehicular complexity
just to get chemical variation with altitude.

Note also re: multitasking that a balloon is probably more mass-constrained than a lander.

I'm not sure cm resolution radar is possible (not at cm wavelengths, anyway...) But in any case
SAR imaging is better done from orbit where you can map the whole planet. (SAR relies on
vehicle motion to synthesize the aperture in any case, so balloon SAR would not be ideal)

A sanitized (minus cost details and proprietary data) version of the Flagship mission report for
Titan (and the others) is supposed to be released to the public next month - you will see there
what the key Titan science from a tropospheric balloon (as opposed to a Lander and Orbiter)
is - high resolution imagery, subsurface radar sounding, and (only if the balloon descends
close to the ground) surface spectroscopy.

Posted by: nprev Sep 3 2007, 04:29 PM

Very illuminating as usual, Dr. L; thanks!

So, the case seems to be well-made that Venusian balloons in themselves do not justify a stand-alone Discovery-class mission. What about making one as a ride-along for a lander or rover? It could go off & do good things at some point during EDL with its own instrumentation...

Posted by: David Oct 19 2007, 06:07 AM

(From Mars & missions - past and future - Mars sample return)

I presume the way to do that would be to keep the balloon (and rocket) high in the atmosphere, and lowering the sampling package to ground level. If you wanted the "lander" to remain stationary, I suppose there'd be a problem either with the balloon-lander cable breaking; the lander being dragged off by the balloon; or the lander being so heavy that it couldn't be retrieved (although I guess only *part* of it needs to be retrieved). But if the plan is merely to hit the ground (possibly in a variety of places), scoop up random samples, and return, that might not be such a big obstacle.

But with an escape velocity close to that of earth, isn't a pretty large rocket needed just to regain Venus orbit?