Publisher’s version / Version de l'éditeur:
Skygazing: Astronomy through the seasons, 2018-10-16
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la
première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
NRC Publications Archive
Archives des publications du CNRC
This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.
For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.
https://doi.org/10.4224/23004533
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at
Life on Mars
Tapping, Ken
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
NRC Publications Record / Notice d'Archives des publications de CNRC:
https://nrc-publications.canada.ca/eng/view/object/?id=e80b4a01-5dc1-4c46-b33c-64bd5251433a https://publications-cnrc.canada.ca/fra/voir/objet/?id=e80b4a01-5dc1-4c46-b33c-64bd5251433a
LIFE ON MARS
Ken Tapping, 16thOctober, 2018
One day, sooner or later, we will be living on Mars, either as visitor explorers and scientists, or as colonists. It might take a while, but if the will is there, our technology will get us to where it becomes economically and logistically feasible. Mars presents a challenge. Its atmosphere is so thin we will need almost a space suit to move around outdoors. What atmosphere there is consists mostly of nitrogen. It is not toxic, but it is of no use to us. There are some other problems. The thin atmosphere means that there is little greenhouse effect to trap heat, so daily
temperatures vary enormously. During the summer it can get above freezing during the day and then go down to 100 Celsius or more below at night. Even though Mars is further from the Sun than the Earth is, the lack of any significant atmosphere means more solar ultraviolet radiation reaches the surface. In addition Mars has no global magnetic field. This, together with the lack of atmosphere means other high-energy radiation can reach the surface of the planet. It could be that living things might have appeared a billion or more years ago, when Mars was warm and wet, but now, with the planet being an almost airless, frozen desert, if anything survives, it must be hiding underground. For a long time our visions of colonies on Mars and similar worlds have been of life under inflated, clear plastic bubbles. Inside you get the sunlight and if the bubbles are made of the right material, the greenhouse effect will provide some solar heating. However, the thin plastic will have little insulation value against low temperatures outside, and warm rising air would be cooled off. It also offers little protection against radiation. A more realistic approach would be to build habitations underground, where a few metres of soil would provide insulation against temperature variations and screening against radiation. However, an interesting dimension here is that there is a lot of ice under the Martian surface. On one side it means we will have locally available water. We
can drink it, and using locally available solar energy, unless there is a dust storm, we can break down that water to get oxygen to breathe. On the other side, building a warm habitation in or on the Martian surface could cause the same problems as we get in the Arctic if we do something that melts the permafrost. We will have to locate our habitations very carefully, otherwise they could end up collapsing in pools of meltwater.
Stays of weeks or months in Earth orbit or on the Moon are very different from the long journey times involved in getting to Mars, and the long stays on Mars made necessary by waiting until Mars and Earth are in the right position for the return trip. Our environmental needs become larger. In addition to the need to meet nutritional and sanitary requirements, there is the problem that we constantly shed flakes of skin, oily sweat, hair, and so on. On Earth we are surrounded by living things, such as bacteria and dust mites, which deal with and recycle them, stabilizing our ecosystem. Otherwise they will accumulate behind panels and in nooks and crannies, becoming food for bacteria and fungi, making us sick. The longer we are away from home, the more of our
ecosystem we will have to take with us.
These days we talk or dream about “terraforming” worlds, changing their atmosphere and other conditions so that we can set up an entire
ecosystem to suit us, and can live with little or no technical assistance. These are at the moment just ideas. Of course, whether we end up terraforming Mars depends on one other issue. If there are still any surviving Martians, we should leave things alone. They might not want us to do it.
Jupiter is lost in the sunset glow. Saturn lies low in the south–southwest after dark and Mars is still bright in the south-southeast. The Moon will reach First Quarter on the 16thand be Full on the 24th.
Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.
Tel (250) 497-2300, Fax (250) 497-2355
