Future Venus Missions Options

[Steve G]

This is a general question about the atmospheres of Venus, Earth, Mars, and Titan. Can someone explain how Mars and Venus are both primarily carbon dioxide and little nitrogen. On the other hand, (before life began on the planet) Earth's atmosphere was largely made up of nitrogen and carbon dioxide gases. Titan is primarily nitrogen. How come Earth's primary atmospheric component is nitrogen when Mars and Venus has hardly any. And why is Titan's so similar to Earth's and not Carbon Dioxide like Mars and Venus?

[mcaplinger]

Short and probably too simple answer: there's lots of N2 on Venus, just not much fractionally. CO2 was removed from the early Earth's atmosphere by formation of solid carbonates (CO2+H2O+mineral reactions). This didn't happen on Venus, perhaps due to lack of water. Titan is so cold that CO2 freezes out so it can't be in the atmosphere. Why Mars has a lot of CO2 and few carbonates (since water was present on early Mars from most evidence) is still something of a mystery.

[Holder of the Tw...]

My turn to oversimplify. Venus' atmosphere is .035 nitrogen. Surface pressure around 92 earth atmospheres. Multiplication gives Venus an atmosphere of nitrogen that is 3.22 times higher pressure than earth's nitrogen/oxygen atmosphere if you removed all the CO2, even with the slightly lower gravity. Under earth gravity the pressure would increase further by around 10%. So, assuming this is a good enough approximation... yeah, Venus has plenty of nitrogen. Even with a surface area 10% smaller than earth, Venus should have around three times the amount of atmospheric nitrogen that we do. Therefore my own question would be... why so much?

[tolis]

Turning to studies of the interior, balloon-borne infrasound detection is considered as a means of seismic sounding:

https://www.jpl.nasa.gov/news/nasa-balloon-...next-stop-venus

[rlorenz]

Turning to studies of the interior, balloon-borne infrasound detection is considered as a means of seismic sounding:

https://www.jpl.nasa.gov/news/nasa-balloon-...next-stop-venus

It's a neat idea, sure. But determining that you have detected a signal above the background in quiet conditions at 3km altitude above California, when you know from a dense seismic network that there was a quake with given characteristics at a given time, is one thing. Floating near the turbulent cloud tops of Venus, where the infrasound background is likely high and poorly characterized, and being able to confidently attribute a signal in there to seismic activity on the surface, would be an altogether different proposition......

[Mongo]

speaking of which, anyone has any "hard" information (papers, abstracts etc.) on the private Rocket Lab Venus mission? other than, I mean, the articles in online media saying that it is being studied with little or no real information...

beside, being old enough to remember private missions which never took off including ISELA, Lunacorp, NEAP, Red Dragon and many more I am not holding my breath for this one

Venus Life Finder Mission Study

The Venus Life Finder Missions are a series of focused astrobiology mission concepts to search for habitability, signs of life, and life itself in the Venus atmosphere. While people have speculated on life in the Venus clouds for decades, we are now able to act with cost-effective and highly-focused missions. A major motivation are unexplained atmospheric chemical anomalies, including the "mysterious UV-absorber", tens of ppm O2, SO2 and H2O vertical abundance profiles, the possible presence of PH3 and NH3, and the unknown composition of Mode 3 cloud particles. These anomalies, which have lingered for decades, might be tied to habitability and life's activities or be indicative of unknown chemistry itself worth exploring. Our proposed series of VLF missions aim to study Venus' cloud particles and to continue where the pioneering in situ probe missions from nearly four decades ago left off. The world is poised on the brink of a revolution in space science. Our goal is not to supplant any other efforts but to take advantage of an opportunity for high-risk, high-reward science, which stands to possibly answer one of the greatest scientific mysteries of all, and in the process pioneer a new model of private/public partnership in space exploration.

The paper talks about the VLF Rocket Lab mission in sections 2 and 3 (pages 15 to 23).

The rest of the paper is even more interesting, talking about the proposed privately funded Venus Life Finder Mission (sections 4 and 5, pages 24 to 33) and the later proposed Venus Atmosphere Sample Return Mission (sections 5 and 6, pages 42 to 52).

[antipode]

Is there any info on whether mission planners expect or need the Davinci+ descent probe to survive on the surface for any length of time?
The mission CGI is amusingly coy on that one as the probe disappears behind a rock!

Obviously we are talking about minutes not hours considering the conditions there, and yes, I know that imaging on the surface probably wont
happen if the probe lands upright (the imager being on the underside i think), but what about the other instruments?

I guess I was hoping for a Huygens-like surface surprise.

Presumably there are limits on how long the orbiter and probe are in line of sight too?

P

[StargazeInWonder]

"The DAVINCI+ probe will also descend over a tessera called Alpha Regio, taking up to 500 images as it falls to the surface. Although the spacecraft will eventually be destroyed, there is a small chance that it could survive on the surface for several minutes before it is wiped out by the intense pressure and temperature. These pictures of the tessera could be enlightening. “Our final images should have a resolution of tens of centimetres,” says Garvin."

https://www.nature.com/articles/d41586-021-01634-3

[antipode]

Thankyou!

P

[rlorenz]

Is there any info on whether mission planners expect or need the Davinci+ descent probe to survive on the surface for any length of time?....

Presumably there are limits on how long the orbiter and probe are in line of sight too?

The mission objectives do not require survival of impact. (as was the case for Pioneer Venus, and Huygens. I was heavily involved in the assessment of post-impact survival and operation of the latter.)

I guess in terms of expectation, you could consider that contact was lost at impact with 3 of the 4 Pioneer Venus probes (quite possibly simply by tipping over and depointing the antenna, rather than due to damage) whereas transmissions from the 4th were received for another hour or so until it got too hot. So maybe there's a 25% chance of continued operation. You could argue that the prior info on the terrain is that it may be rougher than average, so that reduces the odds a little.

In any case (as for Huygens) the relay spacecraft gets too low in the sky to sustain the radio link about 20 minutes after landing even if the probe is upright and still transmitting, so it wont be a long surface mission. And if the probe is upright, then the camera window is embedded in the dirt, so the images will not be exciting.

Ralph

[antipode]

Thankyou Ralph,
its always a pleasure to see your posts,

Id forgotten that one of the PV probes had survived for that long.

Im hoping for a surprise outcome, a good one, even if it is only 20 minutes.

P

[vjkane]

In any case (as for Huygens) the relay spacecraft gets too low in the sky to sustain the radio link about 20 minutes after landing even if the probe is upright and still transmitting, so it wont be a long surface mission. And if the probe is upright, then the camera window is embedded in the dirt, so the images will not be exciting.

Ralph

Anyone on this forum know where the atmospheric sample port is located on this probe. If it would not be embedded in the dirt, then additional or extended composition measurements on the surface might be made.

I suspect that the other good use of any post-impact time might be to relay additional descent imaging data.

[StargazeInWonder]

FWIW, the most important compositional measurements made by DAVINCI+ will be for the heavier inert gases, krypton and xenon, and should have no variations owing to altitude near the surface. Any measurement made in the final few km of the descent will be perfectly adequate. For those who haven't read about it, the methodology that will give great precision over previous measurements is quite clever: First, the composition of a sample of unaltered venusian atmosphere will be made, then chemical processes will remove most of the CO2 and N2 and a compositional measurement of the remaining gases will have much higher precision for those; finally, the sample will be cooled to the freezing points of krypton and xenon, the remaining gases blown way, and a measurement of the Kr+Xe only will be made, pinpointing the isotopic abundances. This will answer questions about the formation of Venus's atmosphere and speak to an outstanding mystery regarding the xenon isotopic abundances in Earth's atmosphere!

https://www.nasa.gov/feature/goddard/2021/davinci-vms

If there are any atmospheric compositional gradients right at the surface, I'm sure we wouldn't mind knowing about them, but the big questions will already be investigated before landing.

DAVINCI+ has a bowl shape and it will descend pretty slowly. Every image from Venera showed rocky rather than dusty or powdery surfaces, so I doubt if there's much chance of the surface making a tight seal against any atmospheric input port, should the craft survive landing.

[atomoid]

DAVINCI uses a sapphire camera window to handle the intense heat and pressure, according to this site the Venera camera windows were quartz. one wonders if saphire was chosen because the thermal expansion characteristics might perhaps be more favorable across expected deep space vs surface conditions?

[Xcalibrator]

DAVINCI uses a sapphire camera window to handle the intense heat and pressure, according to this site the Venera camera windows were quartz. one wonders if saphire was chosen because the thermal expansion characteristics might perhaps be more favorable across expected deep space vs surface conditions?

Could be window transmission. Sapphire is pretty transparent over 0.14-6 microns vs quartz 0.17-3.5 (give or take a bit, depending on window thickness).