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NASA plans two future visits to Venus

It has been 30 years since NASA sent a mission to Venus. Today they announced they would be sending two, one designed to map the surface and a second designed to study the atmosphere.

On Wednesday, NASA Administrator Bill Nelson said the space agency would set its sights on a world that has not received much attention in decades: Venus, the fiery mystery of a planet that’s Earth’s closest planetary neighbor. In an address at NASA headquarters, Nelson said the agency would send not one but two missions there in an effort hailed by scientists as long overdue…

One, dubbed DAVINCI Plus, would send a probe plunging through the planet’s dense atmosphere to understand why it is, as NASA said, “a runaway hothouse compared to the Earth’s.” The mission’s name is an acronym for Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging Plus…

The second mission is called VERITAS and would map Venus’ topography with radar to chart its elevations as well as map infrared emissions to study rock types.

The missions will launch in the late 2020s. The renewed interest in Venus was spawned by claims that there were possible signs of microbial life in the planet’s atmosphere:

In the past year, a neglected Venus re-entered the planetary limelight after a team of scientists using Earth-based telescopes claimed they had discovered compelling evidence for microbes living in the clouds of Venus today where temperatures remain comfortably warm instead of scorching.

They said they had detected a molecule, phosphine, for which they could come up with no plausible explanation for how it might have formed there except as the waste product of living organisms.

But other scientists looking at the same data said they did not observe a convincing signal.

Mars got a lot more attention than Venus in the US, probably because the US sent landers and eventually rovers to Mars while the Soviets decided to focus on Venus. And because the surface of Venus is too hot, too pressurized and too full of sulfuric acid for any technology to survive very long, it makes for very short missions on the surface. Russia’s Venera 13 lander, which arrived on the surface of Venus in March 1982, lasted for 127 minutes. That’s still the record.

But when it comes to Elon Musk’s plan to make humans a multiplanet species, Mars seems like a pretty poor place to settle. It’s too small to hold much of an atmosphere and too far from the sun to hold a decent temperature. The Planetary Society, founded by Carl Sagan in 1980, published an article in April about the possibility of terraforming Mars. The bottom line: It won’t work.

If we stopped or limited Mars’ atmospheric loss, we could hypothetically pursue a number of warming methods. Over the next hundreds of years, we could restore as much as 1/7th the amount of liquid water as Mars once had in its oceans, and bring back some aspects of that period of habitability.

Even then, since Mars has 38% of Earth’s gravity, it can only retain an atmosphere of about 0.38 bar. In other words, even a terraformed Mars would be very cold by Earth standards and its air about as thin and chilly as the Himalayan mountains.

In short, it seems very improbable that we could transform Mars into a more Earth-like planet.

Venus on the other hand, has a size and density similar to Earth meaning similar gravity. It’s problem is a toxic atmosphere but as far as raw materials for an Earth-like planet go, Venus has what Mars lacks. But again, it’s not an appealing destination for expensive experiments because everyone involved knows the missions will end very quickly once the lander reaches the surface.