The Western Lines

April 11, 2009

Venus, not Mars, first

Filed under: Astrobiology,Ralph Buttigieg,Venus — ralphbuttigieg @ 7:54 am
credit NASA

People have been debating whether the next goal for human space exploration should be a return to the Moon or an expedition to Mars for decades. In more recent times there has been serious consideration of another destination, the Near Earth Asteroids. In my view we are forgetting another alternative: Venus.

Suggestions of crewed missions to Venus are usually greeted with disbelieve. The surface of Venus is far too hot, the atmospheric pressure too high and the atmosphere contains sulphuric acid. But paradoxically, its for these very reasons that a Venus mission prior to a Mars mission makes sense.

It will be a very long time before a human landing on Venus can be contemplated. The only realistic mission that can be done in the foreseeable future is an orbital mission. NASA studied a Venus orbital mission using Apollo technology back in 1967. Edward Willis compared a Venus orbital mission with a Mars orbital mission. The result was even the easiest Mars mission required 70% more mass then the hardest Venus mission. A Mars landing would be more difficult still. So in terms of difficulty and therefore cost the choices are:

a) A Venus orbital mission

b) A Mars orbital mission (at least 70% more difficult)

c) A Mars landing (the most difficult)

Venus is the low hanging fruit.

Now critics well say Venus is more difficult because its closer to the Sun. Certainly the solar radiation will be greater at Venusian orbit then at Mars. However making the spacecraft reflective should handle the heat problem. A greater concern is ionizing radiation. Cosmic rays are not linked to the Sun, they are a concern to explorers no matter were they go in the Solar System. So the shorter mission times of a Venus mission reduce the dangers compared to a Mars mission. However solar flares are a real concern, as they are for Mars missions. They can be countered by having a radiation storm shelter. Admittedly the shelter will need to be more massive for Venus but you still have the mass advantage.

A Venus orbital mission would be scientifically rewarding. The astronauts would be spend some 40 days at Venus in a highly elliptical orbit. Combined with Venus’s slow rotation, they would be able to keep in contact with robotic probes for days. They could teleoperate robots without a lengthly time delay allowing for rapid exploration of the Venusian atmosphere by aircraft and the surface.

As to what to look for on Venus, how about life? The surface may be inhospitable but at the 50 km altitude level the temperature is cool enough for liquid water and atmospheric pressure is similar to Earth. In fact , trace gases provide evidence of possible life. In the thick Venusian atmosphere ordinary air becomes a lifting gas which has lead Geoffrey Landis to seriously propose Venusian colonization by aerostat.

So onward to Venus!



  1. I agree with your analysis of the benefits of an orbital mission to Venus, before a Mars mission. Teleoperating probes (in Venus’ case, including floating balloon probes) in real time from either Venus’ or Mars’ orbits would be a great advantage; imagine how much more quickly the MER rovers could explore if we could teleoperate them! Maybe our first goal regarding Mars should be a buried (for radiation protection) base on Phobos. There was a recent article on about a breakthrough, at least in the lab, in small (but completely adequate) electromagnetic/plasma fields, which would provide radiation shielding on spacecraft venturing beyond LEO. The power needed to maintain such shielding would be quite easily achievable with current technology.I also like the idea of an early Orion mission to a near-Earth asteriod; again, this “million mile mission” was described on, as well as in/on other sources.Lets walk before we can run; and lets do these missions sooner rather than later!-Stuart YoungSan Antonio, TX

    Comment by Stuyoung29 — April 13, 2009 @ 1:52 pm | Reply

  2. Teleoperating high-temperature rovers on the surface of Venus would be a good way to look for signs of hydrated minerals in the highlands. If found they’d provide information on how Venus lost its water and how much it originally possessed. Another bonus of Venus is that its atmosphere is more puffed up than Mars’s and thus friendly to aerocapture into orbit around.

    Comment by qraal — April 25, 2009 @ 2:24 am | Reply

  3. I wonder where they are getting the data that the “easiest Mars mission is 70 percent harder than the hardest Venus mission”. Considering a round-trip mission we have the following data assuming Hohmann (i.e., minimum energy) transfer orbits going from a 500 km altitude circular orbit at the originating planet and arriving at a 500 km altitude circular orbit at the destination planet:Earth to Mars delta-v’s:6.10 km/sec leaving1.28 km/sec arrivingtotal delta-v outbound = 7.38 km/secMars to Earth delta-v’s:4.02 km/sec leaving6.10 km/sec arrivingtotal delta-v inbound = 10.12 km/sectotal delta-v round-trip = 17.5 km/secEarth to Venus delta-v’s:5.65 km/sec leaving5.63 km/sec arrivingtotal delta-v outbound = 11.28 km/secVenus to Earth delta-v’s:5.63 km/sec leaving0.66 km/sec arrivingtotal delta-v inbound = 6.29 km/sectotal delta-v round-trip = 17.57 km/secThus, the total delta-v for a round-trip to Mars is approximately the same as a round-trip to Venus.

    Comment by Tom Marking — May 3, 2009 @ 7:08 pm | Reply

  4. G’day Tom.The orbit at destination is a high elliptical, nota low circular. The original NASA paper is here:

    Comment by Ralph Buttigieg — May 5, 2009 @ 12:58 pm | Reply

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    Comment by Alice Thomas — July 19, 2010 @ 6:10 am | Reply

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