Now I will look at the small number of future Venus mission plans which I made maps for. I will come back to flown missions later. First is SAGE (Surface Atmosphere Geochemistry Experiments), a modified Soviet Venera lander suggested for an early Discovery mission and later expanded to include two landers. One would go to a tessera (faulted upland) region, one to the lowland plains. A possible third lander could go to a site of possible active volcanism, if one was found. #venus
SAGE was an attempt by Russian scientists to salvage something from their planetary program during a very difficult period for them. This map shows the upland areas - tesserae - which were of interest. The numbers are rankings - Aphrodite was the top choice, a sprawling continent-sized upland. Two specific sites are noted - we will see them tomorrow. #venus
Here is a closer look at the sites on Venus suggested for the proposed SAGE mission, which of course never flew. One is on top of the plateau of Ovda Regio, part of Aphrodite Terra. The highest terrain on Venus tends to be very bright in radar images, suggesting an unusual composition. This paper offers one explanation:
Treiman, A. et al., 2016. Venus’ radar-bright highlands: Different signatures and materials on Ovda Regio and on Maxwell Montes. Icarus, 280, pp.172-182. #venus
Treiman et al. (one co-author, Elise Harrington, had been one of our students at Western) suggested the following, which I am absolutely unqualified to assess:
"The... substance on the equatorial highlands is likely chlorapatite, formed by reaction between igneous fluorapatite and HCl in the... atmosphere.
On... Maxwell Montes... radar reflectance is consistent with presence of a semiconductor... formed in chemical reaction between the atmosphere and the surface... #venus
The next mission I will look at was another Discovery mission proposal, Venus Exploration of Volcanoes and Atmosphere (VEVA). A balloon would float at a height of 60 km, dropping small probes to the surface along the way. There was a 1 balloon version and a 2 balloon version. An atmospheric probe would be dropped to the surface when the balloon entered the atmosphere, other probes would image the surface during descent. This map shows an overview of the plan. #venus
These are just closer looks at the VEVA sites on Venus. The most interesting sites are near the start, where two probes each would go to Maat Mons and Ozza Mons, two major volcanoes. The descent imaging would have been quite dramatic. The sites further west are in less dramatic settings but still probably very interesting. Descent imaging has never been done at Venus. Think of the descent images of Titan from the Huygens probe. The mind boggles... mine does anyway. #venus
Mission studies are often used as exercises by university engineering classes and end up on the internet. One example from Virginia Polytechnic and State University involved a Venus Sample Return Mission. Only the landing site aspect is covered here. An equatorial site would simplify orbital operations. A large flat landing site was needed and the area chosen was at 1º N, 130º E near Aphrodite Terra, just north of Thetis Regio. That box is about 500 km across. #venus
Here is the site of that Venus sample return mission in more detail. A nice smooth plain surrounded by blocks of faulted uplands (tesserae). The plains are most likely lava flows of various ages. I don't recall how they were going to get that sample back but it's not an easy thing to do.
This was the last map I made before abandoning my Venus atlas project. But I will look at some later missions (real and imagined) briefly before moving on. #venus
Russian scientists have been hoping to return to Venus for a long time. A long-lived lander would be a bold new step, so the mission concept is called Venera-D, where D is the first letter of the Russian word for long-lived. Here are some mission descriptions:
We can summarize the mission's prospects by saying that I do not expect to live to see it (and I am in pretty good health for an old guy). Officially, launch is in 2036 but I doubt it. Too bad, I would like to see it but will content myself with people on the Moon. #venus
From a mission which might fly eventually to one that has already been successful - Europe's Venus Express. This was an atmosphere mission, and I have not said much about the atmosphere of Venus because I am primarily a surface guy. But atmospheres are important too... and Venus Express did give us a glimpse of the surface. Here is a link to a cloud image:
I have a colonoscopy video too. I hope I posted the right one.
Yes, I think I did. The south polar vortex... very weird. You wouldn't want to fall in. But enough about clouds. Can we see through them without using radar? We'll see tomorrow. #venus#venusexpress
It turns out that at some infrared wavelengths the surface of Venus can be detected through the clouds. Infrared - we associate it with temperature and indeed it seems we are seeing the surface temperature which is lower at high elevations. Here is an ESA release on the topic:
The text suggests the image at right is a radar image of Venus but it is really a rendered image of the altimetry data. Can we find it on a map? #venus#venusexpress
Yes, we can. Here is that area on the map I posted earlier.
The infrared image from Venus Express - its VIRTIS instrument - is showing those large tectonic features (Dali Chasma, Diana Chasma). So we know this is possible. Tomorrow, a different view of a broader area. #venus#venusexpress
It shows temperatures at the surface of Venus observed by the VIRTIS instrument on Venus Express. Blue is cooler (high elevations), red is warmer and lower. At right is a Magellan radar global mosaic with elevation colour-coded (blue = low, red = high). Letters show corresponding locations. #venus#venusexpress
These surface maps have very low spatial resolution but they do show the surface. We can do two things with this. First, there are some gaps in Magellan radar altimetry which can be filled in. Second... what if the temperature of an area is not only related to elevation? A recent lava flow would show up as anomalously warm. It would look like a depression where no depression should be. Can we find any examples suggesting recent activity? #venus#venusexpress
Let's start with filling in gaps in Magellan altimetry. Obviously the Venus Express surface temperature maps are much lower resolution, so no big changes in our understanding of Venus. This ESA release shows the gaps (triangular crosshatched areas) overlaid on a map where colours are temperatures. Elevations are shown as contour lines and match temperatures quite well.
Moving on to active volcanism, I was simplifying by only talking about temperature anomalies as a possible way to detect an eruption - there are other things we can look for in the data - but several lines of evidence do suggest active eruptions:
Venus Express is not the only spacecraft which could view the surface of Venus like this. The Parker Solar Probe uses gravity assists at Venus to shape its orbit to make close approaches to the sun, and can image the night side as described here:
goes to a series of beautiful images from Akatsuki showing the ever-changing clouds, including night-side clouds. They were processed by a French image processing virtuoso, Damia Bouic, who has also done lots of good work with Mars images:
