If Saturn’s moon has signs of life, impact with a 15,000 km/h spacecraft won’t stop it

When searching for signs of life in far flung planets or moons, sometimes the details are important.

For example, if a space craft was sent to collect samples from the icy plumes of a distance moon, would the high speed fly-through disrupt properties of the substance it is trying to collect?

Or more directly, could an amino acid even survive an impact with a spacecraft? A new study from researchers from the University of California San Diego says yes.

“The search for extraterrestrial life, especially within our solar system, is one of the biggest endeavours of mankind,” the researchers write in a new PNAS paper detailing the results. 

They say “the icy moons of Saturn and Jupiter, Enceladus and Europa, are particularly promising for hosting life, as they have shown evidence for the three important criteria: water, energy, and organic chemicals. Both moons eject their subsurface ocean material as a plume of icy particles.”

These ice plumes are perfect for a spacecraft to fly through and take a sample of the ice for analysis. There’s been a number of missions suggested over the years, including a privately funded venture called Breakthrough Enceladus.

Cassini even took its own sample of the icy spray over a decade ago.

But spacecrafts fly incredibly fast – 4 or 5 kilometres a second when doing a flyby. That’s more than 15,000 kilometres an hour. Could a small organic chemical, or amino acid, survive an impact this great?

In Cassini’s case, the answer couldn’t tell us everything: “high interaction velocities caused ambiguity as to the origin and identity of the organics,” the team wrote.

“Laboratory validation of this technique is needed to show that biosignature molecules can survive an impact at hypervelocity speeds for detection.”

So, they recreated the impact in a lab.

Using an Aerosol Impact Spectrometer and a Hypervelocity Ice Grain Impact Spectrometer, the team of researchers created their own 800 nanometre icy particles. Then they accelerated them to up to 4.2 km/s and then smashed them at a target.

The results were impressive.

“We show that amino acids entrained in ice grains can be detected intact after impact at speeds up to 4.2 km/s … validating the predictions from other model systems,” they wrote.

“Our results provide a benchmark for this orbital sampling method to successfully detect signs of life and for the interpretation of past and future data.”