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Earlier this week, an international team of astronomers announced they had detected traces of phosphine, a simple molecule associated with living organisms, in the atmosphere of Venus. While it is not definitive proof of extraterrestrial life, it’s hard to explain without invoking extraterrestrial microbes floating in the acid clouds of Earth’s neighbor. The only way to know for certain is to send a spacecraft there to check it out, and the planetary science community is awash in calls for a mission to unravel the mystery. When it comes to the search for extraterrestrial life in our solar system, it seems that Venus is the new Mars.
Peter Beck wanted to send a mission to Venus before it was cool. Earlier this year, the founder and CEO of Rocket Lab, a small launch provider from New Zealand, announced the company’s plan to dispatch its own atmospheric probe to Venus to scout for signs of extraterrestrial life. Beck says he’s had a “long love affair” with Venus and that his desire to send a probe there isn’t just about looking for alien microbes. “Venus has a tremendous amount to teach us about our own planet,” says Beck. “Venus is just Earth gone wrong through climate change, and it can teach us a lot about some of the changes that we see today on our own planet.”
Beck says Rocket Lab has been working on its Venus mission for months and has collaborated with a number of researchers to design its scientific payload, including Sara Seager, a planetary scientist at MIT who was part of the team that recently detected phosphine in the planet’s atmosphere. Beck says the mission would use a modified version of Rocket Lab’s Photon spacecraft, which launched into Earth orbit for the first time this month and will deliver a cubesat to the moon next year for NASA. The Photon spacecraft itself won’t enter into orbit around Venus, but when it flies by the planet it will eject an 80-pound probe. The probe will enter the planet’s atmosphere at over 24,000 miles per hour without a parachute or any sort of braking system to slow it down. During its brief descent, it will sample the atmosphere and relay that data back to its Photon mothership before it succumbs to the brutal conditions near the surface.
“The goal of the mission is to find life,” says Beck. “I’m not naive enough to think that we can be successful on the first go, so I really hope to see a campaign of missions rather than just a single shot.”
Interplanetary missions have historically been the sole domain of national space agencies, due to their incredibly high costs, which typically run into the hundreds of millions of dollars—the cheapest interplanetary mission ever launched was the Indian space agency’s Mars orbiter, and it cost a cool $74 million. That’s hard for a profit-motivated company to justify, since there’s no real business case for planetary exploration. Beck is confident Rocket Lab can buck this trend. The company has the rockets it needs to get there, and now it has the Photon to carry a scientific payload. As for the money, Beck says some things in life are “just more important than trying to make a buck.”
Beck hopes that Rocket Lab’s Venus probe will demonstrate that planetary science missions don’t have to be a once-in-a-decade, billion-dollar affair. “What we’ve tried to develop here with Photon is the ability to go to destinations like Venus on a time frame and cost that’s never been done before,” he says. “It creates opportunities to do many missions quickly and affordably.”
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.
In the early days of planetary exploration, Venus was a hot destination. Between 1962 and 1985, there were 20 dedicated Venus flyby, orbiter, or lander missions. Since then, there have only been three. The detection of phosphine in the Venusian atmosphere has stoked interest in returning to our mysterious planetary neighbor, but we’ll have to wait at least a few years to return. Beck says the earliest Rocket Lab could launch its Venus mission is 2023. If NASA selects Davinci+ for the next Discovery mission, it wouldn’t launch until 2026.
Until then, planetary scientists will have to search for further evidence of Venusian cloud dwellers using Earth-based telescopes or data from opportunistic flybys of spacecraft headed to other planets—like the BepiColombo mission to Mercury, which may look for more evidence of phosphine when it passes Venus next month. When it comes to finding life on Venus, says Byrne, we’re going to need all the data we can get. “What we need is the kind of systematic, thought-out approach that has given us such valuable information for Mars and the moon, where multiple missions tackle different aspects of the planet's characteristics,” he says. “No one single mission is going to answer all the questions we have about Venus, including whether there's life in its clouds.”
