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Future Venus Missions
HSchirmer
post Oct 3 2015, 06:24 PM
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Ok, so I just looked over the recent posts about a Venus-blimp-lifting-body proposal. It occured to me that Venus might be a good topic for wild ideas -

The surface temperatures and pressures on Venus are brutal, it is more like an ocean than an atmosphere. So, what if we treat exploration of Venus more like bathymetry, with a bundle of instruments on a tether. Drop it down, get the data, pull it back up before it melts.

So, here's one. I just read about New York skyscrapers saving power by making ice at night to store cooling power. Occurred to me that something similar might work well on a Venus blimp/flying wing. Solar powered refrigeration units create dry ice. Vent the blimp, drift down to the surface, get your measurements while CO2 evaporation cools the probe. Have the CO2 fill a couple of high temp weather balloons to lift you back up.
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ZLD
post Oct 3 2015, 08:12 PM
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I'd be highly interested to see this seriously explored but I would expect the miniaturization, low power requirements and low mass requirements would prevent this type of mission at this time. However, with enough money, anything is possible in a short time.


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ngunn
post Oct 3 2015, 08:28 PM
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I like the idea of using a phase change to drive raising and lowering through the Venusian atmosphere. Water would be another possible material for this purpose. Perhaps we are in for a new age of steam . . I think we can leave constraints like cost and mass at the door and just think about ideas, as long as they don't require fantasy science. The best ways of exploring Venus will be unique to that world. If the idea's good enough it will be paid for, and hefted. It's time for Venus!
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HSchirmer
post Oct 4 2015, 01:26 AM
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Ok, following up on earlier idea about a Venus probe, a sort of stratospheric diving bell.

If you happen to be 50 kilometers above Venus, it appears to be rather comfortable.
Standard earth pressure, standard earth temperatures, a bit of sulfuric acid rain, but tolerable.

Recent suggestion include a solar powered flying-wing-blimp,

and brain-ship loitering in the cool air, controlling a dumb but heat tolerant rover by radio...

I figure its' about time to think about what other ideas might work?

Lets consider "off the shelf" technology- specifically military cluster bomb tech. We now have cluster bomblets that use rotating laser and infrared scanners to survey the battlefield, identify targets, prioritize targets, and then navigate there.

I would suggest a similar layout, but to deliver science, not semtex.

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vjkane
post Oct 4 2015, 05:07 AM
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There's a blog post with additional information on the Discovery finalists. You can follow links for more detail for several of the proposals.


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Paolo
post Oct 5 2015, 07:39 AM
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QUOTE (vjkane @ Oct 3 2015, 06:04 PM) *
They may need a transfer orbit that provides a specific set of solar illumination and visibility from Earth tracking stations over the entry point.


You may be right. We will probably know more as more info on the mission is released.
BTW, I remember that Magellan too took 15 months and one and half orbit around the Sun to arrive at Venus. In that case, however, the orbit design was due to NASA opting not to launch two back-to-back Shuttle+IUS missions (Magellan and Galileo) on the same Venus launch window.
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JRehling
post Oct 5 2015, 04:06 PM
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It's curious that the landing sites already visited and photographed (Veneras 9, 10, 13, and 14) were in each case close to tessera or highland units, which seems very unlikely given how much of the planet is wide-open flat planitia. They are also in a very narrow band of longitudes due to the combination of the unexplained synchrony between Venus' revolution and the Earth-Venus synodic periods; the re-use of minimum-energy trajectories in every case; and, the desire to have a day-lit landing site. The aforementioned Veneras as well as the Pioneer Day and Large probes all landed within about 30 of longitude. If one of those variables changes (namely, length of cruise), then a totally different band of longitudes will be selected, potentially a wider one if Venus is gibbous rather than crescent at arrival.

Tesserae are pretty widely distributed. Most 60 bands of longitude would give you 1 or more tesserae landing sites to choose from.
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HSchirmer
post Oct 5 2015, 04:52 PM
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QUOTE (ngunn @ Oct 3 2015, 09:28 PM) *
I like the idea of using a phase change to drive raising and lowering through the Venusian atmosphere.


Well, it might only be necessary for raising.
Just occurred to me, after considering the spinning cluster bombs, that probes shaped like maple spinners could make a controlled descent.

If the probes had a camera pointed off-axis, you could naturally build up a spiral image, getting higher and higher resolution as you descend.

Seems that Venus has enough atmospheric diffraction that solar panels on the top and bottom of a wing can provide almost equal power.
So, perhaps a bunch of cube-sats tucked into a maple spinner enclosure, floating at 50km and using solar power to replenish a dry-ice cooling system, then fluttering down to the surface, use CO2 gas to inflate and lift back to 50 km, start all over again.

The other idea, that literally floated in, is to copy orb-spiders. When spiders hatch, they spin a thread, catch a breeze and fly away.
Even heavier adult spiders fly this way although they actually create a 2d "sail" rather than a 1d string.

So, anybody have ballpark energy requirements for probes floating in Venus's CO2 atmosphere, making dry ice to cool a lander, or fabricating polycarbonate sails?
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JRehling
post Oct 5 2015, 06:12 PM
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Great writeup, Van, as always!
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xflare
post Jan 11 2017, 08:11 AM
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Well, the only hope for a Venus mission in the next decades rests with the Venus in situ Explorer now
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vjkane
post Jan 11 2017, 05:05 PM
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I'm listening to Jim Green's program update at SBAG. He has now said several times that the asteroid missions were selected because they were "most technically ready" and "best fit into a cost capped program".

If you look at Lucy and Psyche, the spacecraft are straightforward, the instruments are all near copies of existing instruments, and the data return rates are likely pretty modest. The latter is one of the key drivers of spacecraft cost.

DAVINCI had the challenge of having a carrier probe (simple in itself, but another element), a high pressure vessel, and expensive composition instruments that had to be modified to work with high pressure, high temperature gasses.

VERITAS was using a modification of radar systems used at Earth, but I don't know if any modifications were required. The biggest challenge, I suspect, was the data return rate which would have driven the cost and complexity of the entire spacecraft system. (Ralph Lorenz published a great paper on how data rate is the driver of planetary mission costs.)

Following the cost overruns of the last decade following the selection of more ambitious missions, NASA's managers appear to have become more conservative. While surprises happen (InSight, for example), in general this has worked.


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vjkane
post Jan 11 2017, 05:09 PM
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QUOTE (HSchirmer @ Oct 5 2015, 08:52 AM) *
Just occurred to me, after considering the spinning cluster bombs, that probes shaped like maple spinners could make a controlled descent.

If the probes had a camera pointed off-axis, you could naturally build up a spiral image, getting higher and higher resolution as you descend.

The Huygens probe used spin to build up images. I can't remember if the spin was created by the parachute design or vanes on the probe.


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vjkane
post Jan 11 2017, 05:14 PM
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QUOTE (xflare @ Jan 11 2017, 12:11 AM) *
Well, the only hope for a Venus mission in the next decades rests with the Venus in situ Explorer now

The European community has united behind the EnVision Venus mapping mission for the M5 (fifth medium) class mission. It is similar to VERITAS with the biggest difference being the addition for EnVision of a subsurface radar instrument. We will know if it made the list of finalists mid year this year. Launch target is the very late 2020s.

There's also a joint Russia-US Venera-D mission in early discussion that would include an orbiter (I think without a radar unit) and an atmospheric probe/lander. However, the Russian space program is strapped for cash and has an ambitious lunar program in the queue ahead of any Venus mission.

There's also been vague (in the public press) talk about other space agencies such as China doing some kind of Venus mission.


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rlorenz
post Jan 13 2017, 02:33 PM
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QUOTE (HSchirmer @ Oct 5 2015, 12:52 PM) *
Just occurred to me, after considering the spinning cluster bombs, that probes shaped like maple spinners could make a controlled descent.


Such winged seeds are called 'samaras', and have been proposed for planetary atmospheric sensing, but typically would give you higher angular rates than you would want for imaging. (They are discussed at some length, as well as the spin vanes on Huygens, spinning parachutes, rifled bullets etc in my book "Spinning Flight : Dynamics of Frisbees, Samaras, Boomerangs and Skipping Stones"

Achieving slow descent on Venus is not usually a problem with conventional vehicles, however, since the atmosphere is so dense.

Small vehicles (like the 'cubesat') do not work well in the deep Venus atmosphere as they would warm up very quickly - active cooling doesnt scale down efficiently.


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