Is Ceres Our Third Hub After the Moon and Mars?
Being the largest object in the asteroid belt between Mars and Jupiter, Ceres is 27% the size and 1.3% the mass of the Moon. Its surface gravity is 3% of the Earth’s acceleration, g.
The last detail means that if we ever hold the Olympic Games on Ceres, high jumpers could break the Earth’s record by a factor of (1/3%)=33, reaching a height of (2.45/3%)=81.7 meters! Constructing a pressurized stadium that is large enough to accommodate long jumps would be challenging, since the world record could stretch from 8.95 meters to nearly 300 meters — requiring a base that is at least a percent of the radius of Ceres: 470 kilometers.
Aside from offering an opportunity to break world records, does Ceres provide other benefits to humanity? To appreciate its promise, let us review what is known about it.
Ceres was discovered on January 1st, 1801, by Giuseppe Piazzi at the Palermo Astronomical Observatory in Sicily. Its orbital radius is 2.77 times larger than the Earth-Sun separation and its orbital period around the Sun is 4.6 years. The Cererian day lasts 9 hours and 4 minutes. Based on data from NASA’s Dawn — the first spacecraft to orbit Ceres in 2015, Ceres currently has almost no seasonal variation in sunlight by latitude.
Does Ceres have the necessary ingredients for life-as-we-know-it? Water ice in its regolith varies from approximately 10% in polar latitudes to much drier levels in the equatorial regions. Altogether, Ceres is about half water by volume (compared to 0.1% for Earth) and 73% rock by mass. The active geology of Ceres is driven by ice and brines.
Ceres has the most water of any object in the inner Solar System after Earth, and the likely brine pockets under its surface could provide habitats for life. Its peak surface temperature is 235 degrees Kelvin above absolute zero, or -38 degrees Celsius, similar to the winter surface temperature near the coast of Antarctica. Ceres has a higher surface temperature than the icy moons Europa and Enceladus which are thought to have subsurface oceans.
Ceres contains enough long-lived radioactive isotopes to preserve liquid water under its surface for extended periods that could give rise to organic chemistry. Organic compounds were indeed detected in the Ernutet Crater. Some compounds resembling those found in Enceladus’ plume, have been detected on Ceres’ surface including carbonates, hydrated silicates and ammonium chloride.
In a 2018 paper that I published with my former postdoc, Manasvi Lingam, we studied the prospects for subsurface life in objects like Ceres. We concluded that although subsurface life faces challenges, it could overcome them. We estimated that the number of such worlds could outnumber habitable rocky planets by a few orders of magnitude and therefore constitute some of the most abundant habitats for life.
Given its generous water reservoir, would Ceres be the next destination for a sustainable human base after the Moon and Mars?
One approach to make Ceres habitable is to build domes over its craters, inside of which the surface temperature will be gradually heated and organic molecules will be introduced, thereby creating a terrestrial-like environment. Using water harvested from the surface, this land could be irrigated and oxygen gas could be processed within the domes.
There are many benefits to settling on Ceres. The foundation is rich in resources, including water ices, organic molecules and ammonia, and its surface receives about 150 Watts per square meter of solar irradiance, roughly one ninth that of Earth. This rate of clean-energy supply is high enough for running solar-powered facilities.
Ceres could become a transport hub for future asteroid mining infrastructure, allowing mineral resources to be transported to Mars, the Moon, and Earth. Its small escape velocity, combined with its large supply of water ice, means that it could also process rocket fuel, water and oxygen gas for spacecraft traversing the asteroid belt.
Just as the railroad transportation system empowered the technological revolution of the United States 150 years ago, the Moon-Mars-Ceres hubs could be instrumental for the technological revolution of the Solar system.
But as we settle on Ceres, we might find that other lifeforms preceded us in its subsurface water. This experience will convey a sense of humility. The cosmic play is not about us since we arrived late to the stage. Here’s hoping that we will hear the message loud and clear and be kind to all forms of extraterrestrial life that predated us in the Solar system and beyond.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He chairs the advisory board for the Breakthrough Starshot project, and is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. His new book, titled “Interstellar”, is scheduled for publication in August 2023.