Search for Life Beyond Earth Requires Flexibility in our Understanding

On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Examination of spectral data acquired from orbit show that some of these sediments have minerals that indicate chemical alteration by water. Here in Jezero Crater delta, sediments contain clays and carbonates. The image combines information from two instruments on NASA's Mars Reconnaissance Orbiter, the Compact Reconnaissance Imaging Spectrometer for Mars and the Context Camera. Credit: NASA/JPL-Caltech/MSSS/JHU-APL.

MONTREAL – As space technology improves to look for life beyond Earth, a panel of experts urged that humanity keep itself open about what we might find out there – an important point as a new generation of life-searchers (ranging from Mars 2020 to the James Webb Space Telescope) embark on their cosmic journeys in the early 2020s.

The group at the Montreal Space Symposium on Friday (Oct. 11) was a cross-disciplinary set of experts with specialties ranging in everything from education to astrobiology. And as educational consultant Dianea Phillips explained, proper scientific training begins with childhood.

Educating students

Phillips, who is an educational consultant with the Lester B. Pearson School Board in Montreal, talked about an experiment where she brings a box of Cheerios into a classroom. She asks the children – without giving them any mathematics or other tools beforehand – if they can estimate the number of Cheerio “planets” inside the box. Children try methods ranging from looking through the box (they quickly realize they cannot) to weighing the box to shaking the box, and the award at the end is they get to eat the contents of the box.

She teaches this way, she explained, because it’s important to “not explain with children …. [but] to ask them what they think. Educators all too often try to answer questions. It limits their [children’s] ability to reach forward to get more knowledge.”

As people move forward in their careers, however, they do have access to more sophisticated tools. Life-searching on planets is about to take a big leap forward with the launch of the Mars 2020 rover, a mobile science laboratory that will crawl Jezero Crater in search of ancient habitable environments. The most promising samples will be cached for a sample return mission to Earth in the 2030s or so.

Life on Mars? The moon?

Mars 2020 rover's new landing technique.
Mars 2020 rover’s new landing technique. Image Credit: NASA/JPL-Caltech.

Richard Léveillé is a scientists who studies how microbes influence mineral formation in hot spring environments. “The idea is there is the interaction of those microbes with the minerals that can leave traces,” he explained. He’s not only studied this phenomenon on Earth, but he is bringing his knowledge to Mars already as a participating scientist with the Mars Science Laboratory (or Curiosity rover) team, which has been exploring Gale Crater and Mount Sharp since 2012.

Léveillé, who is also an adjunct professor at McGill University, explained that it is difficult to prove ancient past life even on Earth, where we have access to large laboratories and more sophisticated instruments than can be carried to the Red Planet. (For example, the fossil record from a few billion years back tends to be obliterated over the eons due to plate tectonics and surface weathering). So he advocated that the search for life on Mars should focus on solutions for bringing samples back to Earth.

This will be no easy task, because it is unclear whether any Mars microbes – if they exist – would pose harm to life on Earth. Naturally, scientists won’t want to take any chances. So there will be a strict decontamination protocol for any Martian samples coming back to Earth. This will include the building of sophisticated laboratories similar to the “clean rooms” used now for spacecraft, except this time the goal will be to keep possible Martian microbes in instead of simply keeping Earth microbes out, Léveillé said.

Aerospace consultant and educator Brian Ewenson, whose experience includes working with entities such as Challenger Learning Centers and the Canadian Space Agency, reminded delegates that hardy life can exist even in the harshest of environments. In 1969, the Apollo 12 mission landed two astronauts a short distance from the Surveyor 3 spacecraft that had arrived two years before. The astronauts removed the camera from Surveyor 3 and brought it back to Earth for analysis.

Famously, scientists of the era – who examined the camera after its return to Earth – appeared to find evidence of Streptococcus mitis, a common bacterium on Earth, Ewenson said. But the results remain controversial to this day. Clean room protocols in the late 1960s and early 1970s were not quite as strict as what are used today, so it is difficult to prove whether these were bacteria that travelled to the moon and revived on Earth, or bacteria accidentally transferred during investigations by scientists when Surveyor 3’s camera was returned.

Earth-like exoplanets

Finding Another Earth: Candidate Lineup
A newly discovered exoplanet, Kepler-452b, comes the closest of any found so far to matching our Earth-sun system. This artist’s conception of a planetary lineup shows habitable zone planets with similarities to Earth: from left, Kepler-22b, Kepler-69c, the just announced Kepler-452b, Kepler-62f and Kepler-186f. Last in line is Earth itself. Credit: NASA/JPL-Caltech.

Life in the universe, of course, is not confined to locations such as Mars. Astrophysicist Étienne Artigau, a senior research associate at the University of Montreal, pointed out that there are roughly 4,000 exoplanets discovered and confirmed by various telescopes. The search for life often focuses on planets that are in the habitable zones of red dwarfs, which are slightly dimmer than our own sun. Thus, planets that are potentially habitable – or that would have the ability to host water on their surfaces – would need to huddle in closer to a red dwarf than the equivalent distance at our sun.

Current technology makes it easier to search for planets at such stars because M dwarfs are dimmer (and smaller) than our sun, making it easier to detect planets either by their reflected light or by the “tugs” they produce on the star during their orbits. But in the future, Artigau said, it may be possible to find habitable exomoons. The possibility isn’t too strange, because our own solar system does host many icy worlds such as Europa (at Jupiter) or Enceladus (at Saturn). 

Jupiter-sized planets at other solar systems may have their own moons, perhaps orbiting in “resonant chains” – or with each moon orbiting its home planet in a precise ratio to other moons, Artigau said. He urged more research in this field, saying it is important not to preclude these types of searches because scientists of today may very well see things they don’t understand that could mean life in the future.

Léveillé agreed with this postulation, saying that scientists can’t agree on definitions of life – “Is a blob a lifeform?” – or even on what a planet is, as the ongoing debate about Pluto’s status shows. “We need to look for what we don’t know and keep an eye on interesting things we want to know,” he said. One example of knowledge eluding scientists is the status of salts on Europa, which can be measured spectroscopically – but which appear strange because they are unlike any salt on Earth. These Europan salts have been bombarded by radiation and changed over many years, so Léveillé said more study is needed to learn more about what the nature of these salts may be.

The Blob movie poster.
The Blob movie poster. Credit: Wikipedia.

The panel was moderated by Frédérique Baron, a scientific and educational public outreach coordinator at the Institute for Research on Exoplanets – a cross-institutional group of 40 professors, researchers, post-doctoral fellows and students from the University of Montreal and McGill University. 

In recent news, the institute’s Björn Benneke (who is at the University of Montreal) led a team that detected water vapor on an exoplanet called K2-18b, a planet roughly nine times the mass of Earth. While K2-18b is likely uninhabitable due to a thick gas atmosphere, the study does have promise for finding a water cycle at even smaller planets in the decades to come, researchers said in a statement in September.

Canadian Space Summit 2019

About Elizabeth Howell

Elizabeth Howell
Is SpaceQ's Associate Editor as well as a business and science reporter, researcher and consultant. She recently received her Ph.D. from the University of North Dakota and is communications Instructor instructor at Algonquin College.