The breakthrough of researchers in the scientific community is the unearthing of an immense water reservoir on Mars. Located over a kilometer beneath the surface, the reservoir is primarily composed of ice layers and was discovered through the use of measurements collected by the Shallow Radar (SHARAD) on NASA’s Mars Reconnaissance Orbiter.
Methodology of Discovery
For this discovery, SHARAD deployed radar waves capable of penetrating up to a mile and a half beneath the Martian surface. What they exposed were layers of sand and ice which, in some locations, entailed up to 90% water. The composition of these layers is believed to stem from the accumulation of ice at the poles during past ice ages on Mars. Each warming period covered remnants of the ice caps with sand, consequently shielding the ice from solar radiation and preventing its escape into the atmosphere.
The Significant Findings
This discovery holds utmost significance as the layers of ice present a record of Mars’s past climate. Scientists can study the geometry and composition of these layers as it could reveal whether previous climatic conditions were favourable for lifeforms.
Overview of Mars Reconnaissance Orbiter (MRO)
Launched in 2005, the MRO’s mission is to seek evidence that water persisted on the Martian surface for a considerable time. It possesses a range of scientific instruments like cameras, spectrometers, and radar to analyze Mars’s landforms, stratigraphy, minerals, and ice. The spacecraft houses six primary instruments, as shown in the table below.
| Instrument | Function |
|---|---|
| HiRISE (High Resolution Imaging Science Experiment) | This visible camera reveals objects in the debris blankets of mysterious gullies and details of geologic structures. |
| CTX (Context Camera) | This camera provides views to help offer a context for high-resolution analysis of key spots on Mars. |
| MARCI (Mars Color Imager) | This weather camera monitors clouds and dust storms. |
| CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) | This instrument splits light in its images into hundreds of “colors” that identify minerals, especially those likely formed in the presence of water. |
| MCS (Mars Climate Sounder) | This atmospheric profiler detects variations in temperature, dust, and water vapor concentrations in the Martian atmosphere. |
| Shallow Radar (SHARAD) sounder | It seeks geological boundaries in the first tens to thousands of meters below the surface of Mars. It probes the subsurface using radar waves. |
Role of the Shallow Radar (SHARAD)
SHARAD plays a crucial role in examining the subsurface structures by leveraging radar waves within a 15-25 MHz frequency band to realize high depth resolution. The radar wave return, captured by SHARAD’s antenna, reacts to changes in the electrical reflection characteristics of the rock, sand, and any water present on both the surface and subsurface of Mars. In essence, substances like water and high-density rock, being very conducting, result in a robust radar return. Thus, any alteration in the reflection properties of the subsurface, such as layers deposited by ancient geological processes, is visible. The Italian Space Agency (ASI) provided SHARAD.
