If NASA finds signs of extinct life on Mars, it may be difficult to confirm is in fact what scientists have been looking for for decades.
Why is this important: Finding life on another planet would change our view of what it means to exist in the universe, but an extraordinary life-changing discovery also requires extraordinary evidence.
- “The burden of proof for establishing life on another planet is very, very high,” NASA Perseverance project scientist Ken Farley told a press conference last week.
Driving the news: NASA scientists announced last week that the Perseverance rover on Mars had cached some intriguing information samples that might be able to tell researchers if the Red Planet was once inhabited.
- The rocks were collected in Jezero Crater, which is thought to have been the site of a river delta billions of years ago. They contain organic compounds – molecules that contain carbon and hydrogen but may also contain oxygen and other elements – that can be created by living organisms or other natural processes like the interactions of water with rocks over time.
- One such sample, taken from a rock named Wildcat Ridge, likely formed “when mud and fine sand were deposited in an evaporating saltwater lake,” NASA said in a statement. . statement. Perseverance analyzed the rock with its SHERLOC instrument, revealing that it contains more organic compounds than any other sample collected so far.
- “We’re looking at rocks that were deposited in a habitable environment, with good preservation potential at a time on Earth when life already existed,” Farley said in an interview with Axios.
Yet scientists will have to wait until this sample and others are returned to Earth to find out if these compounds mean life once thrived on Mars.
How it works: Once back on Earth, scientists will use powerful laboratory tools to analyze the samples.
- These tools are far more powerful than any instruments researchers are currently able to send to Mars in a relatively small rover, increasing the chances of determining whether a given organic compound originated from life.
- If a lab were to find what it thinks is a biosignature inside one of these samples, it would probably have to bring in another lab to look into the context of the find, including the type of rock in which he was found, Farley said.
The plot: In order to determine whether these samples contain evidence of life, scientists will need to assess any degradation of the sample from Mars’ extreme environment and confirm their findings with several tools.
- This is actually a new kind of science, so defining what is considered a true signature of life will be a challenge in itself.
- Organic compounds also degrade over time with exposure to space radiation, which constantly bombards Mars. Scientists have to deal with the natural radioactive decay of elements like uranium and potassium also found on Mars.
- “Inevitably, organic molecules will have seen a lot of ionizing radiation, and that means we’re not looking for proteins. We’re not looking for DNA,” Farley said. This will make it harder to confirm that the organic materials scientists are studying were created by life.
What to watch: NASA is set to launch its sample return orbiter to Mars in 2027, along with the lander for the mission launch the following year.
- Once there, NASA plans to load the perseverance samples cached on the lander. If all goes as planned, the samples should be back on Earth by 2033.