The Perseverance rover, which landed on Mars this month, marks a new leap towards answering fundamental questions about our solar system, including where else we might find DNA. The rover will roam the surface of Mars looking for signs of life, make its own oxygen, launch a helicopter, and collect soil and rocks for a follow-up mission in 2028. If all goes as planned, Nasa, with the help of European Space Agency (ESA) spacecraft, will return soil samples in the spring of 2032 – the first Martian material to visit Earth.
Finding DNA on Mars would not be a complete surprise. Though Perseverance was constructed in the Spacecraft Assembly Facility (SAF) clean room at NASA’s Jet Propulsion Laboratory (JPL), even that setting cannot be made 100% free of background microbial or human DNA. We have known about “microbial hitchhikers” since the very first interplanetary missions in the 1960s, when scientists such as Carl Sagan highlighted the problem. It is a persistent, unavoidable risk of space science. Because scientists must build the spacecraft one layer at a time, shedding skin and droplets of saliva over years of construction, it is almost certain that a little bit of California DNA just landed on Mars.
As such, when the samples arrive on Earth in 2032, they will need to go through a “planetary-scale genetic filter” to rule out any DNA that might have been present in the SAF during the rover’s construction from 2015-20, as well as any other fragment of DNA observed on Earth up until the launch of the spacecraft in July 2020. This is an ongoing project between our laboratory at Weill Cornell Medicine and JPL. By sequencing the DNA found in, around, and on the SAF during the construction of robots, we will draw up a genetic map to avoid or minimise any forward or backward contamination (where we send genetic material somewhere else, or genetic material from somewhere else lands here).
Ever since the first two Soviet probes landed on Mars’s surface in 1971, followed by the US Viking 1 landing in 1976, some fragments of microbial and possibly human DNA are likely to have ended up on the red planet. And given the planet’s global dust storms, this DNA is almost certainly located in various places across the surface.
Fortunately, we are living in an extraordinary era for genetics. The low cost of DNA sequencing allows us to build an ever-growing genetic catalogue of life on Earth, genetic maps of SAF clean rooms, and the first-ever planetary-scale genome maps (MetaSUB and the Earth Microbiome Project). Moreover, in a 2016 mission with astronaut Kate Rubins, we showed that we can sequence DNA in space and match it to profiles of novel organisms on Earth. Anything that can survive in space, on spacecraft, or in extreme conditions on Earth is a decent candidate for life that can survive on Mars. Eventually, instead of sending DNA to Mars by accident, we will do it deliberately, for a purpose.
After all, manned missions to Mars are technologically achievable. They can bring out the best in humanity, and we already have the physical, pharmacological, and biological means to pursue them. A new book, The Next 500 Years: Engineering Life to Reach New Worlds, highlights studies performed on dozens of astronauts, including the twins Scott and (US Senator) Mark Kelly, following Scott’s one-year mission in space. Based on the findings, there is confidence that humans can travel to Mars, and with some additional innovation and technology, stay there.
We need humans to be able to live on Mars sustainably, responsibly, and safely not so that we can abandon Earth, but because the best way to ensure our species’ survival is to make it possible to live elsewhere. Mars is not Plan B: it is Plan A, and always has been.
We have an ethical duty to prevent our own species’ extinction as well as that of all others on Earth. No other species (that we know of) possesses such awareness of its potential future, nor the ability to preserve life. Only we can perform this function; and in the long term, doing so requires that we make our way to other planets. – Project Syndicate
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