But Venus is a particularly hostile destination. On the surface, temperatures are hot enough to melt lead, and the atmospheric pressures are intense. Things are a bit more tolerable high in the atmosphere where researchers recently detected phosphine. Here, temperatures hover around a balmy 80 degrees Fahrenheit, atmospheric pressures are slightly lower than those at sea level on Earth, and the sun is visible through the clouds. Sure, those clouds are made of a corrosive sulphuric acid, and the high-altitude winds whip around the planet at tornado-like speeds. Still, it’s paradise compared with the surface.
Many planetary scientists, including Carl Sagan, have long suspected that relatively clement conditions high above Venus’ surface could support microbial life. The recent detection of phosphine in the upper Venusian atmosphere is the best evidence yet that there might be something to that theory. But whether the phosphine points to life or is just the result of some weird high-temperature reaction we don’t yet understand requires sending an intrepid robot to find out. “No matter what you find, the amount of learning is going to be tremendous,” says Beck.
If Beck’s vision comes true, Rocket Lab would be the first company to launch a private interplanetary mission. But while its Venus probe could certainly yield some interesting data about the planet’s atmosphere, some experts aren’t sure the probe would be big enough to carry the kind of tech it would need to sniff out signs of phosphine, much less life itself.
“Small probes, like that proposed by Rocket Lab, are unlikely to have the mass to carry more sophisticated instruments such as mass spectrometers, which are exactly the kind of tools we need to really get to the heart of this phosphine detection,” says Paul Byrne, a planetary scientist at North Carolina State University. “Rocket Lab’s mission could give us key physical measurements of the region of the atmosphere where this gas was detected, but to really answer this question we need at least a dedicated orbiter to search for phosphine and then a mission to the clouds themselves—not a descent probe, but an aerial platform of some sort.”
Seager, who has collaborated with Rocket Lab on its probe, says it should be possible to identify complex molecules that wouldn’t exist without life. “A probe without a parachute could last up to an hour, and there are instruments that take one second to make measurements,” she says. Still, she agrees with Byrne that an aerial platform is the ideal way to search for life on Venus.
It’s not a new idea. In the 1980s, the Soviet Union launched a pair of Venus landers—Vega 1 and 2—that each released a balloon-borne probe during their descent to the surface. Those probes only transmitted for around a day before going dark, but they operated in the part of Venus’ atmosphere where researchers found phosphine. Ballooning on Venus has only grown more attractive since the Vega missions, after companies like Google demonstrated it’s possible to keep large balloon-borne payloads aloft at high altitudes for months at a time on Earth. In 2018, NASA’s Jet Propulsion Laboratory initiated a study of possible Venus balloon probe concepts, and the agency has also explored whether the Venusian clouds could support crewed missions in blimplike spacecraft. But so far none of these ideas has moved beyond a conceptual stage.
That doesn’t mean NASA is ignoring Earth’s fiery sister. Earlier this year the agency announced the finalists for its next round of Discovery missions, and two of the four missions selected for further study have Venus in their sights. One of the Discovery proposals, Davinci+, is similar to Rocket Lab’s envisioned Venus mission. The NASA researchers plan to drop a spherical probe from a Venus orbiter that would slowly descend to the surface under parachute. On its way down, it would use an onboard chemical laboratory to sniff out gases in the atmosphere. It would focus on rare inert gases like krypton and neon that could shed light on Venus’ history, but there is the possibility it could also look for gases like phosphine that are associated with living organisms. Lori Glaze, the director of NASA’s Planetary Science Division, says the Davinci+ scientists can’t speculate on the possible capabilities of the mission while the team competes for selection in the agency’s Discovery program.