Neil deGrasse Tyson explains why NASA's discovery means there are high expectations of life beyond Earth

We have been talking about life on Mars for a long time and now scientists have finally found some evidence of it. In September, NASA's Perseverance rover made a breakthrough discovery when it excavated the site of an ancient river delta on the planet and found organic matter indicating that Jezero Crater had potentially habitable environments 3.5 billion years ago.
 
Speaking to CNN about this discovery, astrophysicist Neil deGrasse Tyson explained that the research shows the prevalence of "water elsewhere" other than Earth. "This continues to affirm the possibility—let me even say [the] likelihood—[of] the prevalence of organic molecules elsewhere, not just on Earth. By the way, we found organic molecules in meteorites that fell from space. So, all the basic ingredients are there, the question is what kind of spark is necessary to go from inanimate organic molecules to self-replicating life. That's a big frontier in biology today but it happened on Earth and it happened pretty quickly.”

He added that the discovery "gives very high expectations for there to be life, in many many places, possibly in our solar system but certainly across the galaxy.”

The latest Perseverance research has been mentioned in three extensive studies which were published last week, one in the Science journal and two in the Science Advances journal. Abigail Allwood, a geologist at the NASA Jet Propulsion Laboratory in Pasadena, told Washington Post that they found organics "in pretty much every rock."

Caroline Smith, who works at the Natural History Museum, also spoke to CNN about the discovery and the clues it provides about past life on Mars. "So what we found with the data that's been come back from the rover and has been studied for the past few months is that we see igneous rocks that have been formed through volcanic processes which have also been affected by the action of liquid water. That's really interesting and exciting because liquid water is one of the key ingredients that you need for life to start," she said.

Speaking about the presence of organic molecules, she said: "Organic molecules are chemical molecules made of the elements carbon, hydrogen, nitrogen, oxygen, sometimes with some sulfur, sometimes with some phosphorous and maybe some added up things. Those are really really important because you need organic molecules for life to start and the other thing that is really important about organic molecules is that they can be fossil evidence, sort of fossil chemical evidence, of potential past life.”
 
However, she stated that we "can't conclusively say or guess those are evidence of past life" based on the discovery of organic molecules just yet.  "To be able to do those types of experiments, we would really need to do detailed experiments in lapse on Earth that we hope to do in the 2030s," she added.
 
Smith also discussed why it's better to send astronauts than rovers. "I'm a great believer in humans, we have in-built curiosity, we can make decisions very quickly, and we have a high degree of autonomy, much more than the rovers, even though they are fantastic. To really push those frontiers of exploration for the moon and for Mars and potentially elsewhere in the solar system, I think we would always want to have human astronauts going to those places," she said.
 
The Perseverance rover landed in Jerezo Crater on February 18, 2021. Since then, it has been roaming and caching rock samples along the way.  The ultimate mystery to be solved by such research is the question of what happened to the planet—which was seemingly congenial to life—that turned into such a harsh place.

Scientists point out that Mars lacks a global magnetic field like Earth's, that protects the atmosphere from the corrosive effects of the solar wind. They also note that it also lacks plate tectonics, which is a geological process on Earth that recycles the crust and continues to expel large quantities of water and nutrient-rich lava through active volcanoes. 

Benjamin Weiss, a planetary scientist at MIT and co-author of two of the papers, said: "On balance, we are actually super lucky that there are igneous rocks in the crater, and that we happened to land right on them since they are ideal for determining ages and studying the past history of Mars' magnetic field."