Editor’s Note: Jonathan Lunine is the David C. Duncan professor of physical sciences at Cornell University. In 2023, he served on the NASA Mars Sample Return Independent Review Board. more views on CNN.
How poor is our planet’s ability to support life? The answer may come from one of our closest planetary neighbours.
Orbiting spacecraft and rovers deployed to Mars over the past two decades have found strong evidence that conditions billions of years ago were very different from today’s dry, cold environment. When and why did Mars change? Understanding Mars’ past could provide important clues about our own planet’s future.
Today we are on the verge of answering these questions. Designed and built by NASA’s Jet Propulsion Laboratory (JPL), the Perseverance rover has been collecting samples since 2021 to be sent to Earth on a technologically daring mission called Mars Sample Return (MSR), which is currently in development.
But the political storms still hitting Washington, D.C., threaten to leave these precious samples stranded on Mars, giving NASA far less than it needs to design and build the spacecraft that will return the samples. Unless Congress restores this funding, scientists may never see them.
To understand the priceless value of the samples, we only have to look at where Perseverance landed: a crater called Jezero. At the western edge of the crater is a river channel and large deposits of sediment that geologists call river “deltas,” which resemble places on Earth where rivers meet the sea. Today, there is no water in the river channel and the delta lies on a dry and barren crater floor. But both are evidence of ancient times when water flowed on Mars, breached the crater wall, and sediments poured into a vast crater lake.
Did water flow on Mars long enough for life to begin? Why and when did these and other oases dry up?
To answer these questions, Perseverance is collecting samples from the crater floor, the delta, and the hills above it. It is carefully guided by a large team of scientists who are world-class experts on the geology and climate of ancient Mars. The rover itself is a mechanical marvel that drills into rock and packs powdered material into more than 30 sample containers the size and shape of laboratory test tubes. Inside these tubes are priceless Martian samples that hold clues about when and how Mars transitioned from Earth-like habitability to uninhabitable desolation.
To learn the history of Mars and its climate from these rocks, they must be analyzed by massive, power-hungry and user-intensive instruments on Earth. These instruments can detect the presence of materials inside a spacecraft at concentrations that cannot be reached by much smaller instruments carried directly to Mars.
Terrestrial laboratories also have the unique ability to precisely measure the ages of rocks using a technique called radioisotope dating. Finding the exact ages of lunar rocks was among the most important results of the Apollo missions, placing the earliest history of the Earth and the moon on an absolute timeline. Being able to create such a chronology for the history of Mars would be a very profound scientific result.
Mars Sample Return is among the most challenging and complex robotic missions ever attempted and requires the largest lander ever deployed to Mars, carrying a rocket that will launch samples from the surface into Mars orbit. Another spacecraft to be built by the European Space Agency will take the sample capsule from orbit and send it towards Earth. This mission was named the top priority for U.S. planetary exploration over the next decade in two major strategic plans of the U.S. National Academy of Sciences.
However, the samples may never be returned. Legal chaos in Washington this year has left NASA without a definitive budget for this fiscal year, forcing the agency to plan for the lower of two proposed funding levels for Mars Sample Return. As a result, hundreds of people were laid off at JPL earlier this year and the project came to a halt.
Perseverance continues to fill its sample tubes and awaits the day when a ship will take these priceless Martian samples back to Mother Earth. Will the US complete its mission or allow an emerging space power like China to take them back? Or will the samples be left on Mars? If the Mars Sample Return were the first major space mission that we failed to complete due to failure of will, what would be the impact on the nation’s long-standing leadership in deep space exploration?
Mars holds secrets about what makes it possible for a planet to support life, locked in samples waiting to return to Earth. Just this month, Congress reaffirmed MSR as a top priority of the 2022 Planetary Science Decadal and tasked NASA with developing a realistic plan and funding profile to enable the return of samples. NASA needs to submit this plan to Congress as soon as possible so that Congress can move forward with adequate funding. Leaving samples stranded on Mars would be a national disgrace.
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