Future Venus Missions Options

[Phil Stooke]

Oh well, might as well start that new topic since it's already well advanced in the Juno area...

My perspective on landers is as follows. All the landers we've had so far were dropped blind onto an essentially unknown surface. Any future landers can be targeted for specific terrains. It really is not true that we have had representative landings. Even a descent image or two, a panoramic photo plus a bit of surface composition, from a simple Venera-class lander just updated a bit, would be useful if we could put several down at well chosen targets. My choices would be:

Examples of the main plains units (smooth, fractured, ridged)

tesserae

high elevation radar-bright tesserae

large fresh lava flow unit ('fluctus')

crater dark parabola

crater ejecta outflow unit

dunes area.

And I have always assumed, rightly or wrongly, that it would be relatively easy to put these down, so they ought to be fairly inexpensive as planetary landers go.

Phil

[Guest_BruceMoomaw_*]

Well, it's a fact that E.E. Barnard -- one of the sharpest-eyed of all astronomers (which is how he discovered Amalthea) -- is also the only naked-eye astronomer to swear that he saw Mars covered with craters.

[ljk4-1]

Well, it's a fact that E.E. Barnard -- one of the sharpest-eyed of all astronomers (which is how he discovered Amalthea) -- is also the only naked-eye astronomer to swear that he saw Mars covered with craters.

There was an article in Sky & Telescope magazine (exact issue I do not recall,
but likely within the last 10 years) that claims the craters he saw were actually
the Tharsis volcanoes.

But why were scientists so surprised when Mariner 4 found so many craters
on Mars? Did they really expect the planet to have more erosion mechanisms?

[Bob Shaw]

There was an article in Sky & Telescope magazine (exact issue I do not recall,
but likely within the last 10 years) that claims the craters he saw were actually
the Tharsis volcanoes.

But why were scientists so surprised when Mariner 4 found so many craters
on Mars? Did they really expect the planet to have more erosion mechanisms?

George Pal put craters on Mars in the 1950s! So they must have been not far below the surface of the semi-technical consciousness...

Bob Shaw

The following are the best references I have found online:

The Venus-Halley Missions, Don P. Mitchell

The above covers the entire flights and the origins of the ballon plan. The following two pages from Astronautix.com provide additional information into the original VeGa plan, which would have seen four probes launched, two of which would have been dedicated ballon carriers.

Vega 5VS and Vega 5VK

Graham

Graham:

Thanks - none of these offer very much in terms of detailed construction, though...

Bob Shaw

[Guest_DonPMitchell_*]

Bob, what in particular did you want to know about the construction of the Vega aerostats?

[Bob Shaw]

Bob, what in particular did you want to know about the construction of the Vega aerostats?

Don:

I've only seen (a very few) poor quality illustrations of their design - they've always struck me as being one of the more fascinating unsung planetary missions (probably well covered in French, though!). It's primarily the general layout, the deployment, and suchlike which I'd like to learn more about!

Bob Shaw

[Guest_DonPMitchell_*]

Don:

I've only seen (a very few) poor quality illustrations of their design - they've always struck me as being one of the more fascinating unsung planetary missions (probably well covered in French, though!). It's primarily the general layout, the deployment, and suchlike which I'd like to learn more about!

Bob Shaw

Blamont's book (in French) talks at length about this. The Vega balloon mission didn't have much to do with the French. In 1978, Blamont proposed an idea to send a much more complex mission to Venus that involved a big metal-foil balloon probe and an orbiter to relay its telemetry. As far as I know, nothing was ever built or designed in detail. The Mars sample-return mission was sucking the life out of their space budget though, so they sent the Venera-11/12 mission, and botched up some aspects of it. The head of NPO Lavochkin was fired after these probelms.

The Vega probes were designed at Lavochkin, based on a proposal by V. Linkin and others. It's made of teflon and nylon, and quite a bit smaller that what Blamont had proposed.

The idea of combining a Venus mission with a rendezvous with Halley's comet is from Vladimir Kurt. He and a mathematician worked out the celestial dynamics, and got it approved. Some kind of serious falling out occured between Kurt and Sagdeev though, so you don't see Kurt's name mentioned much, even though he was a primary mission planner for Vega.

Here is a diagram of the deployment:

[attachment=5484:attachment]

Here are a couple pretty good diagrams of the aerostat:

[attachment=5481:attachment]

[attachment=5480:attachment]

[Bob Shaw]

Don:

Thanks!

I hadn't previously realised that the entry/deployment sequence was quite so complex - I'd presumed (for no good reason that I can think of) that the lander simply had a bolt-on atttachment which was the ballooon and whatever bits were required to set it going! It's really impressive that a clockwork spacecraft could do so much and so well.

Bob Shaw

[Guest_DonPMitchell_*]

Don:

Thanks!

I hadn't previously realised that the entry/deployment sequence was quite so complex - I'd presumed (for no good reason that I can think of) that the lander simply had a bolt-on atttachment which was the ballooon and whatever bits were required to set it going! It's really impressive that a clockwork spacecraft could do so much and so well.

Bob Shaw

Yeah, the balloon and helium bottles were stored on a ring-shaped unit that wraped around the lander antenna.

The Russians were very good at clockwork. You wouldn't believe what one of those PVUs looked like! Think, miniaturized Babbage difference engine.

The main spacecraft had a real computer on it, but not the lander or aerostat.