NASA/JPL/Cal Tech
March 17, 2022 was a tough day for Jorge Vago. Vago, a planetary physicist, is leading the science for part of the European Space Agency’s ExoMars program. His team was just months away from launching Europe’s first Mars rover – a goal they had been working towards for nearly two decades. But on that day, ESA cut ties with the Russian space agency over the invasion of Ukraine. The launch was scheduled for the Baikonur Cosmodrome in Kazakhstan, which is leased to Russia.
“They told us to call off the whole thing,” says Vago. “We were all grieving.”
It was a painful setback for beleaguered robber Rosalind Franklin, who was originally cleared in 2005. Budget issues, partner switching, technical issues and the COVID-19 pandemic had all in turn led to previous delays. And now a war. “I spent most of my career trying to get this thing off the ground,” says Vago. To complicate matters, the mission included a Russian-made lander and instruments, which ESA member states would need money to replace. They considered many options, including simply placing the unused rover in a museum. But then, in November, a lifeline came when European research ministers pledged €360 million to cover mission costs, including replacing Russian components.
When the rover finally takes to the skies, hopefully in 2028, it will have an array of advanced instruments on board, but one in particular could have a huge scientific impact. Designed to analyze any carbonaceous material found beneath the surface of Mars, the rover’s next-generation mass spectrometer is the linchpin of a strategy to finally answer the red planet’s most burning question: is there evidence of life in it? the past or the present?
“There are many different ways you can look for life,” says analytical chemist Marshall Seaton, a NASA postdoctoral program associate at the Jet Propulsion Laboratory and co-author of a paper on planetary analysis in the Annual Review of Analytical Chemistry. Perhaps the most obvious and direct route is simply to search for fossilized microbes. But nonliving chemistry can create deceptively lifelike structures. Instead, the mass spectrometer will help scientists look for molecular patterns that are unlikely to form in the absence of living biology.
Hunting for the patterns of life, rather than structures or specific molecules, has an added benefit in an alien environment, Seaton says. “It allows us to search not only for life as we know it, but for life as we don’t know it.”
ESA/ATG Media Lab
Packing for Mars
At NASA’s Goddard Space Flight Center outside Washington, D.C., planetary scientist William Brinckerhoff shows off a prototype rover’s mass spectrometer, known as the Mars Organic Molecule Analyzer, or MOMA. The instrument, which is about the size of a carry-on suitcase, is a labyrinth of wires and metal. “It really is a workhorse,” says Brinkerhoff as his colleague, planetary scientist Xiang Li, adjusts the propellers on the prototype before demonstrating a carousel of monsters.
This working prototype is being used to analyze organic molecules in Martian soils on Earth. And once the real MOMA reaches Mars, roughly in 2030, Brinckerhoff and his colleagues will use the prototype — as well as a pristine copy preserved in a Mars-like environment at NASA — to test modifications to experimental protocols, solve problems that crop up during facilitate the mission and interpretation of Mars data.
This latest mass spectrometer can trace its origins back nearly 50 years to the first mission to study the Martian soil. For the 1976 twin Viking landers, engineers miniaturized room-sized mass spectrometers to about the footprint of today’s desktop printers. The instruments were also on board the 2008 Phoenix lander, the 2012 Curiosity rover and later Mars orbiters from China, India and the US.
Those who visit Brinckerhoff’s prototype must first pass a display case with a disassembled copy of the Viking instrument on loan from the Smithsonian Institution. “This is like a national treasure,” says Brinckerhoff, enthusiastically pointing to components.
Mass spectrometers are indispensable tools used for analytical chemistry in laboratories and other facilities around the world. TSA agents use them to test luggage for explosives at the airport. EPA scientists use them to test drinking water for contaminants. And drugmakers use them to determine the chemical structures of potential new drugs.
Many types of mass spectrometers exist, but each “is a three-piece instrument,” explains Devin Swiner, an analytical chemist at the pharmaceutical company Merck. First, the instrument vaporizes molecules in the gas phase and also gives them an electrical charge. These charged or ionized gas molecules can then be manipulated with electric or magnetic fields so that they move through the instrument.
Second, the instrument sorts ions by a measurement that scientists can relate to molecular weight so they can determine the number and type of atoms a molecule contains. Third, the instrument records all “weights” in a sample along with their relative abundance.
With MOMA on board, the Rosalind Franklin rover will land in a spot on Mars that likely had water, a critical ingredient for ancient life, about 4 billion years ago. The rover’s cameras and other instruments help select samples and provide context about their environment. A drill extracts old samples up to two meters deep. Scientists assume that’s far enough, says Vago, to be shielded from cosmic rays on Mars that break up molecules “like a million tiny blades.”
Space-based mass spectrometers must be robust and lightweight. A mass spectrometer with MOMA’s capabilities would normally take up several workbenches, but it has shrunk considerably. “To be able to take something as large as a room the size of a toaster or a small suitcase and send it into space is a very big deal,” says Swiner.
