Possible signs of life on Mars
For centuries, scientists have asked whether life is unique to just our planet.
In a new study the Mars rover, Curiosity, found elements that here on Earth are the building blocks of life. However, even if it links to life, it may have been created abiotically, or without lifeforms.
Amy Williams, an astrobiologist at the University of Florida and a scientist on the NASA Curiosity and Perseverance rovers, said Curiosity was able to discover this using a new technique called thermochemolysis.
“It's just a technique that you heat up a sample and you use a specific chemical with it, that's the thermos-chemo part of thermochemolysis,” Williams said “This is a new chemical we had not used on any flight mission before it's called TMAH…the chemical is really powerful, and that it's able to break apart larger, what we call macro molecular carbon. So, picture is almost what the material is that makes up, sort of like oil and gas, but it's not, it's not from, necessarily from life, you can make it abiotically.”
That process is made possible because of SAM, or the Sample Analysis at Mars, a suite of instruments on the rover. It includes 74 cups that deliver samples into an oven to start the thermochemolysis process.
From SAM and the samples, Williams said the findings allow scientists to see new possibilities about how life was created here on Earth.
“That material probably was the seed stock for the origin of life as we know it, at least on Earth,” Williams said. “So, you are seeing similar sort of feed stock falling on Earth and Mars. I'm viewing this as a way of thinking about sort of the things that were falling to Mars early on in its history. These rocks are maybe three and a half billion years old so that's still a billion years after the planets finished accreting.”
For Williams, she said finding this evidence within the samples is groundbreaking. She said that she expected that these molecules would not survive the radiation environment.
“It's actually really exciting to see that complex, macromolecular carbon like this is preserved,” Williams said. “It's sticking around. We're able to detect it even after billions of years. So, I think what you're getting from this is more of the story of how Mars was a habitable world in its ancient past, how we have all of the components that you need for life as we know it. We just haven't found that life yet on Mars.”
Bennu’s bouldery surface
The asteroid Bennu’s surface is covered in boulders that lose heat quickly. Scientists now know why.
The spacecraft OSIRIS-REx collected a sample from Bennu and delivered it back to Earth in late 2023. It’s a type of asteroid that’s carbon rich and could offer hints to the origin of life.
By taking surface temperature measurements, scientists learned that Bennu has low thermal inertia. It easily heats up and cools down, reacting to the day-night cycle like sand rather than stone.
Andrew Ryan, researcher at the University of Arizona, said the temperature change is caused by a large number of cracks in the boulders.
“We were expecting to find beaches, and we got there, and it was boulders all the way down,” Ryan said. “[Bennu] rotating every day, day in and day out for thousands, millions of years. You're heating and cooling those boulders, and they expand and contract over and over, and that introduces stresses into the material that can be manifested as cracks that begin to propagate.”
Bennu is a second-generation asteroid, or a fragment of a larger planetary body. In addition to the temperature changes, mineral deposits suggest that some cracks were formed by water from the parent body.
Ryan said these findings will help researchers interpret asteroid data in the future.
“We're going to be able to do a better job of understanding what might that asteroid be made of. That's useful for science and it's also useful for planetary defense, like if one of those asteroids is on a trajectory towards Earth,” Ryan said.
OSIRIS-REx's journey isn’t complete. The spacecraft has been renamed OSIRIS-APEX and will study the asteroid Apophis as it travels past Earth.
“Apophis will not hit the Earth, but it's going to be an amazing research opportunity, and that is a stony rubble pile asteroid.” Ryan said. “We'll get a second asteroid under our belt. We'll probably learn a lot of very interesting things when we see Apophis.”
