On Monday, astronomers announced an exciting discovery about Venus’ clouds: They seem to contain phosphine, a toxic and flammable gas that could be a sign of life.
On Earth, the only naturally occurring phosphine ever found is a byproduct of bacteria. In other words, it’s made by a living organism. So if Venus does indeed have phosphine, and it’s not created by some geochemical process we don’t yet understand, it would mean we’re not alone in the universe — not even in our own solar system.
“It’s very hard to explain the presence of phosphine without life,” Dr. Jane Greaves, an astronomy professor at Cardiff University and lead author of the study, said at a press briefing.
Still, many astronomers think there are other possible explanations for the gas’ presence. Phosphine has been found on Saturn and Jupiter too, for example, since those planets’ immense pressure can squish phosphorus and hydrogen atoms together. (Venus is too small to produce such pressure, though.)
There’s only one way to figure out what’s up on Venus: more research, preferably via a spacecraft that can check out the planet up close.
Such missions are extraordinarily expensive and take years to plan, so the earliest mission to Venus would likely be at least three years away. But in a remarkable coincidence, a spacecraft on its way to Mercury just happens to be weeks away from a Venus flyby right now, as Forbes’ Jonathan O’Callaghan reported.
The spacecraft, called BepiColumbo, launched in October 2018. It carries two satellites: one from the European Space Agency and one from the Japan Aerospace Exploration Agency. Its mission calls for these satellites to explore Mercury from different angles.
BepiColumbo is scheduled to enter Mercury’s orbit in December 2025. Before that, though, it has to slow down enough to get captured by the planet’s gravity. So it’s flying by Mercury six times – and before that, by Venus twice – to use the planets’ gravitational forces to curb its speed.
Its first trip past Venus is scheduled for October 16 — just a month from now.
“It’s kind of perfect timing,” Jörn Helbert, from the German Aerospace Center, told Forbes.
Helbert helps manage the MERTIS instrument, the device on the European satellite designed to study the atmosphere of Mercury. Helbert believes his team can use MERTIS to study Venus’ atmosphere during the flyby, but they aren’t sure.
“We are now seeing if our sensitivity is good enough to do observations,” Helbert said.
If it is, the instrument could potentially confirm the existence of phosphine on Venus.
It’s unlikely that astronomers will detect anything on the first flyby
Even if the MERTIS instrument is capable of searching for phosphine or other compounds in Venus’ atmosphere, it’s unlikely astronomers will detect anything on next month’s flyby. That’s because they haven’t had much time to prepare, and the BepiColumbo spacecraft will still be 10,000 kilometers away from Venus at its closest pass.
But in August 2021, the spacecraft will fly by Venus again. That time, scientists behind the mission will have had nearly a year to prepare, and will have learned from that first flyby. Plus, BepiColumbo will get much closer to Venus next time — only about 550 kilometers away.
To detect phosphine on the first flyby, the team would have to get “very, very lucky,” Helbert told Forbes. “On the second one, we only have to get very lucky.”