NASA considering sending a fleet of spacecraft to Venus

Thursday, March 19, 2009

Venus doesn't look like this yet.

Do it do it do it!

Two high-altitude balloons built to hover in sulphuric acid clouds could be part of a future fleet of spacecraft sent to Venus, a NASA advisory team says.

The multi-billion-dollar mission concept – which is being considered for launch in the next fifteen years – could help reveal more about Venus's runaway greenhouse effect, any oceans it may once have had, and possible ongoing volcanic activity.

It could be the next flagship mission sent to a planet, after a planned mission to Jupiter and its moons set for launch in 2020.

The Venus mission would cost some $3 billion to 4 billion and would launch between 2020 and 2025, according to NASA, which in 2008 tasked a group of scientists and engineers to formulate goals for the mission.

Venus is a severely overlooked destination, and needs to be studied in further detail for a number of reasons:

1) its similarity to Earth,

2) the cloudtops might harbour some sort of microbial life for all we know,

3) humans could settle the cloudtops as well.

And of course, in the very far future we may be able to change the entire climate of the planet as well.


As always though, I have issue with the temperature of Venus always being reported in a slightly misleading way. Take a look at this:

The landers, which would only last a few hours in the intense heat, could look for evidence of minerals formed by water. Since such hydrated minerals have a limited lifetime, they could help reveal how long Venus's oceans might have lasted, a question that could shed light on whether life might have arisen on the planet.

The first link there leads to the following information:

The surface of Venus broils at a temperature of about 450 °C - hot enough to melt lead. Several probes in the Soviet Venera and Vega series, as well as a NASA Pioneer Venus probe, landed on Venus and returned data from the surface in the 1970s and early 1980s. But they all expired in less than 2 hours because of the tremendous heat.

Now, two NASA researchers have designed a refrigeration system that might be able to keep a robotic rover going for as long as 50 Earth days. The work was carried out by Geoffrey Landis and Kenneth Mellott of NASA's Glenn Research Center in Cleveland, Ohio, US.

The problem with that is that the surface temperature is not 450 °C, but 380 ~ 450 °C depending on altitude. It might seem like splitting hairs considering how both 380 °C and 450 °C are searingly hot, but when considering the life of a surface mission this can make quite a difference. Surface pressure is also much lower at higher altitudes on the surface.

In any case, this is welcome news. Don't forget that in cosmic terms Venus is just around the corner, so even though the missions won't launch until after 2020 they'll arrive just a few months after they lift off. Compare that to a probe like New Horizons, which launched in 2006 and won't arrive until 2015.

4 comments:

Anonymous said...

The problem with that is that the surface temperature is not 450 °C, but 380 ~ 450 °C depending on altitude.

Well, 375-525°C, more accurately.

I did bring this up in the actual presentation version of the paper you mention-- here, for example, is the link to an overview talk on Venus exploration that I gave at MIT, and I on slide three (slide four in the file, since they added the abstract, I think) I mention the temperature at the top of Maxwell Montes.

It was one of the first things I looked at, but for the case of exploration technology, it turns out to be a distinction that makes little difference. Silicon-based microelectronics won't work at 380°C either, and although it would take the heat a little longer to diffuse into the electronics box, the difference lifetime is not enough to make a significant difference in mission design. 380°C is still hotter than your oven when it's in the broil cycle, and to the electronics, it's still too hot.

Me said...

Hi, and thanks for the clarification. What of the difference in atmospheric pressure when it comes to mission design? There seems to be much more variation there (90 bars at "sea" level vs. 50 bars or so for 10 km up) compared to the difference in temperature.

Anonymous said...

Different people have proposed different approaches to dealing with the pressure. (My proposal was to pressurize the interior with a halocarbon so that the net differential was zero). Overall, pressure is not as bad a problem as the temperature, but there's one big footnote to that-- the heat transfer into the probe from the surrounding atmosphere is likely to have a component that's going to increase with the atmospheric pressure, so the pressure does make the thermal problem worse.

Geoffrey A. Landis said...

Different people have proposed different approaches to dealing with the pressure. (My proposal was to pressurize the interior with a halocarbon so that the net differential was zero). Overall, pressure is not as bad a problem as the temperature, but there's one big footnote to that-- the heat transfer into the probe from the surrounding atmosphere is likely to have a component that's going to increase with the atmospheric pressure, so the pressure does make the thermal problem worse.

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