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Human Missions to Venus: Madness? Maybe Not…
NASA is quietly considering sending astronauts to the Earth’s twin planet
Might we one day send astronauts to Venus? The idea is not quite as farfetched as it sounds. True, the surface of the planet is quite literally hell — temperatures soar to hundreds of degrees and the air is filled with deadly sulphuric acid — but the upper atmosphere is something quite different, almost Earth-like.
Plans to visit Venus have centred around two possible concepts. The first, considered seriously in the 1960s and 70s, would see astronauts fly by the planet, scanning it from close range but not sticking around for long. The second would have astronauts stay for longer, perhaps for years, living in giant airships floating high in the Venusian atmosphere.
That second approach is the one recently considered by NASA. Their plan suggested a long-term strategy to prepare Venus for human habitation, beginning with a series of experimental robotic missions to test the idea. Later humans would make the long voyage, staying on Venus for longer and longer periods.
At an altitude of fifty kilometres, roughly thirty miles, where they propose to fly their airships, Venus takes on surprisingly pleasant characteristics. The temperatures, hot enough to melt lead at the surface, fall to around seventy degrees Celsius (160°F). Air pressures resemble the Earth’s surface, as does gravity. And, importantly, Venus’ atmosphere still provides high protection against the Sun’s radiation.
All those factors mean that the upper Venusian atmosphere may be one of the most Earth like places in the Solar System — far more easy-going on humans than any part of Mars. Encased inside a floating airship, future astronauts may not feel all that far from home.
Even so, life in Venus’ skies would be challenging. People living in airships would have little freedom, their world restricted to a few thousand cubic meters. Some fundamental questions seem unanswered — where would all the necessary food and water come from? Could they grow enough plants to support a long term colony? And what happens when the airship breaks down?
Instead, this kind of habitat would be limited to certain applications. Researchers may visit for brief periods, much as we now send scientists to Antarctica. But it is hard to imagine anyone choosing to live and die on Venus. And surely the planet could never support a large, growing population of the kind needed to colonise Venus.
For these things, planets with habitable surfaces, like Mars, are much more appealing. But the idea of visiting Venus, at least temporarily, does hold another attraction: the planet is by far the easiest one to reach.
That opens up opportunities for ambitious mission planners. Unlike Mars, for which flights must be carefully scheduled to synchronise with the planet’s distant orbit, Venus allows many more chances to visit. That permits more risk, and a faster iteration of designs and concepts.
If nothing else, then, Venus could act as a test bed for human spaceflight. Heading to Mars is a long term commitment. Visitors must be prepared to spend months, even years, on the surface of the planet. For Venus trips could be much shorter. Astronauts could spend a month floating through the Venusian atmosphere, observe the planet in detail, and then head back home.
Should anything go wrong, that greater degree of flexibility could be lifesaving — something that could be vital in the early, experimental, stages of interplanetary exploration. That benefit, though, can be obtained even without involving airships. Just reaching Venus would, for now, be a major achievement.
This brings us back to the first option, one that NASA last considered in the 1970s. Back then the space agency had a super powerful rocket — the Saturn V — and wanted to put it to work exploring the Solar System. One option proposed to send a team of astronauts towards Venus, skimming its surface, before heading for home.
That voyage would have involved a spaceflight of one year, by far the longest time anyone had spent in space (though it is worth noting that astronauts have since exceeded that in orbit around the Earth). Perhaps more importantly, it would have served as a test of how humans respond to the deep isolation of interplanetary travel. From Venus, Earth appears as nothing more than a tiny speck of light, shimmering in the void.
Ultimately NASA shelved the idea, facing funding cuts after the end of the Apollo Program. The Soviet Union had a plan to visit Venus too, but after the space race ended and interest in long-range flight waned, their plans were also abandoned. Venus itself, once the target of dozens of probes, lost its allure.
The abandonment of the planet is stark to see. Between 1961 and 1978 thirty missions targeted the planet. Since 2000, less than half a dozen have. NASA has peppered the surface of Mars with rovers, dedicating years to the study of the Red Planet. The surface of Venus, by contrast, has seen only a handful of probes — and a combined exploration time of just ten hours.
That made last year’s shock announcement of possible biology on Venus all the more stunning. NASA has dedicated huge resources to finding life on Mars. Were they looking in the wrong place all along?
Though those claims have been criticised, and may have been mistaken, the interest it created has pushed space agencies to return to our twin planet. NASA recently announced two new missions to explore the planet. ESA plans its own mission, as does Russia.
The rapidly expanding private space industry is also showing an interest in Venus. RocketLab, an American manufacturer of rockets, is planning to send a small probe towards the planet as soon as 2023. Others may follow with missions of their own.
This brings up one final, intriguing point. Might Venus become a testing ground for companies like SpaceX, bent on colonising Mars? Could they beat NASA in sending the first humans to another world? Venus, long overlooked, is starting to attract its fair share of attention.
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