For more than two decades, the presence of an ancient Martian ocean has been a source of academic controversy. In recent years, radar and visual maps provided by orbiting space probes have strongly supported the existence of an ocean, billions of years ago. The European Space Agency’s “Mars Express” orbiter, for instance, detected probable ocean floor sediments in regions ringed by ancient Martian shorelines. Scientists at the University of Colorado at Boulder also mapped river deltas on the Martian service that apparently fed into vanished oceans. Now, planetary scientist Geronimo Villanueva and a team of researchers have published an article in the journal Science that provides compelling new evidence for a vast, long-lived Martian ocean. Their article has received major media attention, and, as of this writing, is on the front page of CNN.
Even without that breakthrough, human exploration and colonization of Mars will be influenced by the history of the planet’s atmosphere, hydrosphere, cryosphere, and perhaps biosphere. The presence of water on Mars will be essential for the survival of future colonists. The historical transformation of Mars from habitable world to frozen wasteland provides a window into what might have been on Earth, and that will encourage scientific missions. The Martian past might even provide a romantic stimulus for a terraforming project that aims to restore the planet to the liveable world it once was.
Author's note: I explore these ideas in greater detail in a journal article that I am preparing for submission.
Villanueva, G. L., M. J. Mumma, R. E. Novak, H. U. Käufl, P. Hartogh, T. Encrenaz, A. Tokunaga, A. Khayat, and M. D. Smith. "Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs." Science, 2015. DOI: 10.1126/science.aaa3630