Venus, not Mars, first

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!