Astrobiology is working to answer three fundamental questions. Find out what they are and how NASA is coordinating efforts to get to the bottom of them.
Is there anybody who hasn’t gazed up at the night sky and asked themselves if somebody was looking back at them? I don’t imagine there’s ever been a person in this world who’s been that short on curiosity.
As soon as we learn that there are other worlds out there, we can’t help speculating on what those worlds are like and who might live there. That used to be something that scientists studied independently from different angles in various disciplines.
They eventually realized that the scientific fields around life on other planets overlapped. That started a new subject.
new subject called astrobiology
First, they called it exobiology to bring them all together. Over time, it became the field of astrobiology.
Astrobiology is the study of the origins of life here and the search for life beyond Earth. You might be tempted to think that, since we haven’t found any life beyond Earth, there wouldn’t be much for people working in this field to do.
That’s not the case at all. NASA’s Astrobiology Institute coordinates a grassroots community of hundreds of scientists as well as sister organizations like the European Space Agency. They’re all working toward NASA’s ambitious Astrobiology Strategy.
The strategy begins with three questions. How does life begin and evolve? Does life exist elsewhere in the Universe? What is the future of life on Earth and beyond? We’ll cover each of these below.
How Does Life Begin and Evolve?
The problem in trying to answer this question is that so far we only have one example of the process–our own planet. Evolution happens at a glacial pace, so we can’t observe the origin and evolution of life directly in one human lifetime.
What we can do is look at fossils and the characteristics of the plants and animals around us. That’s how Darwin came up with his theory in the 19th century.
Lately, we’ve been able to map the genomes of humans and other species and also recover DNA from fossils. This is giving us new insights into the tree of life and how living and extinct species relate to one another.
From that, we’ve established that evolution is a scientific fact. The diversity of life we see all around us came from descent with modification in a world of natural selection.
Exactly how the whole process started is harder to pin down. That happened an unimaginably long time ago under very different conditions than we have today.
ABIOGENESIS IS THE SUBJECT OF HOW LIFE BEGAN
That subject is called abiogenesis. Although it doesn’t have all the answers we need, it does raise the right questions. Sometimes that can be more important.
According to NASA’s astrobiology program, the questions around abiogenesis include:
“What were the steps that led inanimate materials – rocks, sediments, organic compounds, water – to come together and build living organisms, with replicating genes, cell walls, and the ability to reproduce?
• What led to the proliferation of new life forms on Earth?
• How do water and essential organic compounds arrive on planets and moons, and how do they interact with the planets and moons they land on?
• Is it possible to learn from chemicals and minerals on the surface of planets whether microbes might live there, including beneath the planet’s surface?
• Is it possible, likely even, that life exists elsewhere based on elements other than carbon and a system different than DNA? Could such life even exist here on Earth, but is as yet undetected?”
Does Life Exist Elsewhere in the Universe?
There’s a story that Carl Sagan used to share a story about a major newspaper asking a famous astronomer to write 500 words on whether there was life on Mars. The story goes that he wrote back, repeating the two words “nobody knows, nobody knows” 250 times.
The same answer still applies today, not only about Mars but about life on other planets in general. Even so, we know a lot more about life on Mars than we used to.
For example, Mars wasn’t always a freezing cold desert, like we see in pictures today. It used to be both warmer and wetter.
MARS WOULD HAVE BEEN JUST AS LIFE-FRIENDLY AS EARTH
It would have been just as life-friendly as Earth for most of its life. What’s more, all the things life needs to flourish were there. Mars had the right chemicals, sunlight and liquid water in a nice, stable environment for millions of years.
That doesn’t prove much in itself. On the other hand, look at it this way. Finding out that there was once life on Mars would shift the odds of life elsewhere in the universe enormously.
We might find out that there isn’t any life anywhere in the solar system except on Earth. Then, we might be justified to go on thinking that our planet is something very special.
Conversely, imagine discovering life in our solar system. That would probably mean that there are life forms out there on billions of other planets to be discovered.
What is the Future of Life on Earth and Beyond?
This is the hardest question of all. We know that there are threats to life on Earth right now. Most of them are of our own making. These include land and sea use, direct exploitation of organisms, climate change, pollution and invasive alien species.
These are all things that we need to urgently address. What’s important here is that they also tell us about the conditions needed to sustain life elsewhere. Our biggest challenge with this question is that we may or may not be heavily biased.
WE MAY OR MAY NOT BE HEAVILY BIASED
All we really know about planets and habitable zones comes from our experience here on Earth. Our planet might be a helpful guide for predicting where else life might exist.
On the other hand, it might be limiting our understanding of what habitable worlds are really like. That might be pointing us in the wrong direction. Life may exist in places we think of as extreme environments. Nobody knows.
There’s a lot more to the NASA Astrobiology Strategy than these three questions on which it’s based. We plan to return to it from time to time and cover more topics from it. These will include the six major astrobiology research topics, the five goals for the astrobiology community and related topics.
We always have more to learn if we dare to know.
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