Date: 07/10/2022

Relevance: GS-3: Science and Technology- developments and their applications and effects in everyday life.

Key Phrases: Liquid water on Mars, South Pole of Mars, Spacecraft Laser-Altimeter, Mars Express, MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), subglacial lakes

Context:

• A team of researchers has found new evidence for the possible existence of liquid water beneath the south polar ice cap of Mars.

Background:

• The study published in the journal Nature Astronomy is the first independent evidence of liquid water beneath Mars’ South Pole using data other than radar.
• The researchers, led by the University of Cambridge, used a spacecraft laser-altimeter.
  • Measurements of the shape of the upper surface of the ice cap to identify subtle patterns in its height were carried out.
  • It showed that patterns match computer model predictions in the same way a body of water beneath the ice cap would affect the surface.
• The results are in agreement with earlier ice-penetrating radar measurements which predicted a potential area of liquid water beneath the ice.

Significance of the study

• The liquid water interpretation from the radar data alone has been subjected to debates as some studies suggest the radar signal is not due to liquid water.
• This study is the best indication that there is liquid water on Mars today.
  • There is evidence which suggests the existence of subglacial lakes on Mars like the Earth.

Does life exist on Mars?

• Liquid water is said to be found on Mars which is an essential ingredient for life but still there is no evidence of existence of life on Mars.
• In order to be liquid at such low cold temperatures of Mars the water beneath the South Pole might need to be really salty.
  • This would make it difficult for any microbial life to inhabit it.
• However, the existence of water on Mars gives hope that there were more habitable environments in the past when the climate was less unforgiving.

Exploring water on the Mars's surface

• Ice is present on the Mars
  • Like the Earth, Mars has thick water ice caps at both poles whose combined volume can be equated to the Greenland Ice Sheet.
  • Earth's ice sheets which are underlain by water-filled channels and even large subglacial lake
  • The polar ice caps on Mars have been thought to be frozen solid all the way to their beds due to the cold Martian climate.
• Technological constraints
  • European Space Agency's Mars Express satellite in 2018 revealed an area at the base of the ice that strongly reflected the radar signal
    • Which was interpreted as an area of liquid water beneath the ice cap.
    • The Mars Express satellite has an ice-penetrating radar called MARSIS, which can see through Mars' southern ice cap.
    • Other studies suggested dry materials which exist on Mars, could produce similar patterns of reflectance if they exist beneath the ice cap.
• Geothermal heat source will aid existence of water
  • Mars has a very cold climate, thus liquid water beneath the ice cap would require an additional heat source, such as geothermal heat from within the planet.
  • The combination of the new topographic evidence, modal results and the radar data make it look at least one area of subglacial liquid water exists on Mars today
    • Mars must still be geothermally active in order to keep the water beneath the ice cap liquid.
• Shape of ice sheets is crucial
  • On Earth, subglacial lakes affect the shape of the surface topography of the overlying ice sheets.
  • The water in subglacial lakes lowers friction between the ice sheet and its bed, affecting the velocity of ice flow under gravity.
    • This in turn affects the shape of the ice sheet surface above the lake, often creating a depression in the ice surface followed by a raised area further down-flow.

Research methodology

• Researchers used a range of techniques to examine data from NASA's Mars Global Surveyor satellite of the surface topography of the part of Mars’ south polar ice cap where the radar signal was identified.
• Analysis revealed a 10-15-kilometre-long surface undulation comprising a depression and a corresponding raised area, which deviated from the surrounding ice surface by several meters.
  • This is similar in scale to undulations over subglacial lakes here on Earth.
• The team then tested whether the observed undulation on the surface of the ice could be explained by liquid water at the bed.
• They ran computer model simulations of ice flow, adapted to specific conditions on Mars.
• They then inserted a patch of reduced bed friction in the simulated ice sheet bed where water would allow the ice to slide and speed up.
• The researchers also varied the amount of geothermal heat coming from inside the planet.

Conclusion

• The extensive experiments generated undulations on the simulated ice surface that were similar in size and shape to the real ice cap surface.
• The similarity was observed between the model-produced topographic undulation and the actual spacecraft observations.
• This with the earlier ice-penetrating radar evidence suggests that there is an accumulation of liquid water beneath Mars’ south polar ice cap
• This magmatic activity occurred relatively recently in the subsurface of Mars to enable the enhanced geothermal heating needed to keep the water in a liquid state.

Source: The Hindu

Mains Question:

Q. What do you understand by the “Goldilocks Zone”? Why is Mars the most explored planet in the Solar system? Will the future manned space mission to Mars be mainly a technological race between superpowers or rather an international research mission? (250 words).