Resolved Cold Case: Unveiling Hidden Ice Reserves on Mars through NASA’s Maps

The shaded regions on this Martian map indicate areas where NASA missions have discovered subsurface water ice, stretching from the equator to 60 degrees north latitude. This map, an integral part of the Subsurface Water Ice Mapping (SWIM) project, will aid in determining optimal landing zones for the first human explorers on Mars. Credit: NASA/JPL-Caltech/Planetary Science Institute

The map will assist NASA in selecting the most suitable landing locations for the initial human expeditions to Mars. The greater the availability of water, the less the need to transport water from Earth.

The concealed ice will be an invaluable asset for the pioneering humans landing on Mars. It will serve both as a source of potable water and a crucial component for rocket fuel. Moreover, this ice holds significant scientific interest. Future astronauts or robotic missions could extract ice cores for scientific examination, much like similar activities conducted on Earth, revealing Mars’ climatic history and possibly indicating former or existing microbial habitats.

The latest Mars global maps demonstrate the probable existence of water ice buried within the top three feet (approximately one meter) of the Martian surface. These maps are the most recent output from the SWIM project. The concealed ice will be an essential resource for astronauts, functioning both as drinking water and an essential element for rocket propulsion. Credit: NASA/JPL-Caltech/Planetary Science Institute

Mars’ Precarious Water Conditions

The necessity to search for subsurface ice arises from the instability of liquid water on Mars’ surface, which vaporizes immediately due to the planet’s thin atmosphere. While abundant ice exists at the Martian poles, comprised mainly of water and some dry ice (carbon dioxide), these areas are excessively cold for either human astronauts or robotic missions to endure for extended periods.

Introduction to the SWIM Project

The NASA-funded Subsurface Water Ice Mapping project, colloquially known as SWIM, recently unveiled its fourth series of maps, marking the most intricate data sets since the project’s initiation in 2017.

Directed by the Planetary Science Institute in Tucson, Arizona, and supervised by NASA’s Jet Propulsion Laboratory (JPL) in Southern California, SWIM consolidates information from several NASA missions. These include the Mars Reconnaissance Orbiter (MRO), 2001 Mars Odyssey, and the now-defunct Mars Global Surveyor. By amalgamating various data sets, researchers have pinpointed the most promising areas for locating accessible Martian ice for upcoming missions.

The image of an impact crater revealing ice is indicative of what scientists aim to discover for mapping prospective astronaut landing sites on Mars. Such impacts have been incorporated into the most recent versions of NASA-funded maps showing subsurface water ice on Mars. Credit: NASA/JPL-Caltech/University of Arizona

Onboard instruments have identified what appear to be extensive deposits of subsurface frozen water across Mars’ mid-latitudes. These latitudes are particularly appealing due to their denser atmosphere, facilitating a spacecraft’s deceleration during descent. Ideal landing locations would lie on the southern extremity of this region—sufficiently north to assure the presence of ice, yet proximate to the equator to maximize temperatures for astronauts.

Sydney Do, JPL’s SWIM project manager, stated, “Human missions to Mars would ideally be situated as close to the equator as feasible to minimize the energy requirements for heating astronauts and their associated equipment.”

Advancements in Mapping Techniques

Earlier versions of the map employed lower-resolution imaging tools, radars, thermal mappers, and spectrometers. Although these could suggest the presence of buried ice, they could not definitively verify its quantity or existence. For the most recent SWIM map, high-resolution cameras aboard the MRO were used. For the first time, HiRISE (High-Resolution Imaging Science Experiment) data was included to provide an unparalleled view of the ice boundaries nearest to the equator.

Frequent use of HiRISE enables the study of newly formed impact craters, likely revealing chunks of ice beneath the surface. In 2022, HiRISE documented a 492-foot-wide (approximately 150 meters) impact crater, exposing a substantial cache of hidden ice.

New Insights and Future Avenues

In addition to revealing impacts, the updated map incorporates features known as “polygon terrain,” produced by the seasonal expansion and contraction of subsurface ice, resulting in polygonal ground cracks. This adds further evidence to the presence of additional hidden ice.

Nathaniel Putzig, co-lead of SWIM at the Planetary Science Institute, noted that ice distribution across Martian mid-latitudes is uneven, which remains an open question. The latest SWIM map could contribute to new theories explaining these variations and may assist in refining models about Mars’ ancient climatic evolution.

Researchers involved in SWIM anticipate that their work will lay the groundwork for a proposed Mars Ice Mapper mission. This future orbiter would be outfitted with a specialized radar designed to search for near-surface ice in areas not yet confirmed by HiRISE.

Frequently Asked Questions (FAQs) about Mars Ice Mapping

More about Mars Ice Mapping

• NASA’s SWIM Project
• Mars Reconnaissance Orbiter (MRO)
• Mars Odyssey
• HiRISE – High-Resolution Imaging Science Experiment
• Planetary Science Institute
• Mars Exploration at NASA