The Search For Life on Earth

Pictured above is a really bad glitch from an early-1980s video game. Or maybe it’s a picture of a cell under some sort of weird microscope. Or maybe it’s what happens when you put an apple into an MRI?

Nope. It’s a picture of the Earth, taken from a thermal imaging spectrometer orbiting Venus. And it’s one of the weird ways we look for aliens.

In 2005, the European Space Agency (ESA) launched Venus Express, its frst-ever effort to explore our planetary neighbor one hop closer to the sun. The major mission of Venus Express was, per the ESA, to engage in “the most comprehensive study of the Venusian atmosphere” then to-date. It by all accounts, Venus Express was successful. It arrived at Venus in April of 2006, originally with the hope that it could orbit the planet for 500 days, taking detailed images of the planet’s atmosphere and cloud cover and send those back to us back here on Earth. It delivered on that promise — many of the best images we have of Venus are from Venus Express — and it greatly outlasted the promised 500 days. Venus Express’s mission, originally, was set to expire in February or March of 2007, but it managed to keep functioning until early 2015. The ESA lost contact with Venus Express on January 18th of that year, and the craft is believed to have burned up in Venus’ atmosphere in the subsequent weeks.

To get that job done, the ESA outfitted Venus Express with the “Visible and Infrared Thermal Imaging Spectrometer,” or “VIRTIS,” a device used to measure different parts of the electromagnetic spectrum (e.g. visible infrared light, as its name says). VIRTIS wasn’t intended to take measurements from extraordinarily long distances — as Venus was more than 2.1 million miles (3.5 million km) from Earth, Venus Express had to go to Venus to effectively use it to map the atmosphere. But while it was there, Venus Express didn’t just study Venus. It also was able to study Earth: by looking for signs of life. From that really far distance.

As the ESA further noted, from Venus Express’s Venusian perspective, the Earth “appear[ed] as a single dot with no visible surface details.” That’s not dissimilar to the best tools we have, right now, to study exoplanets outside of our own solar system. Using VIRTIS, Venus Express began searching for evidence that Earth may be habitable. Or, more accurately — as we already know that Earth has life on it (hi!!) — the ESA was hoping to see what life looks like, in aggregate and from very far away, using thermal scanning tech. The image above is, basically, what that looks like. And VIRTIS also gave us a comparison for the image; per ESA, “the Moon has also been observed, providing additional observations of particular interest for calibrating the instrument.”

While the VIRTIS view of Earth is valuable, it, alone, has not proven very promising toward our search for extraterrestrial life. The good news, according to VIRTIS Co-Principal Investigator Giuseppe Piccioni (in one of the above-linked stories), is that “we [saw] water and molecular oxygen in Earth’s atmosphere,” even at this great distance. But “as Venus also shows these signatures, [. . .] looking at these molecules is not enough” to conclude that anyone’s living here.


Bonus fact: In 2013, with tensions high between India and China, the Indian army was on high alert. When they noticed some strange objects in the sky above, they began monitoring them, suspecting that China had deployed spy drones in Indian air space. The monitoring went on for about six months, according to the BBC, before Indian authorities realized that they were looking at Venus and Jupiter.

From the Archives: Venusian Blinds: An ill-fated attempt to see Venus do something cool from Earth — to say the least.