Since it means any signs is likely to be buried underground, Discovery has implications for search for life on the planet
Experiments with compounds reveal the light which bathes the entire world turns into bactericides themsterilising the layers of the landscape.
The discovery suggests that assignments will need to dig to find existence when it lurks there and has consequences for the search for life on the rock from sunlight. Three or two metres may lie beneath the surface where some other organisms and the soil are protected from radiation. “At these depths, it is possible Martian life may endure,” said Jennifer Wadsworth, a postgraduate astrobiologist at Edinburgh University.
The discovery of oxidants known some years ago drove Wadsworth’s study. The space agency’s Phoenix lander and Mars rover showed up in tests conducted by Nasa’s Viking lander missions but confirmed hints of perchlorates. The Mars Reconnaissance Orbiter seen signs of perchlorates in what seemed to be moist and streaks that seeped down crater walls and Martian gullies.
Scientists suspected that perchlorates would be poisonous for Martians, but in theory at least, germs that were alien might find a way to use the chemicals. Then aliens may be flourishing in the spots on Mars if life could flourish in brines.
She discovered that the bugs were wiped out. Other perchlorates had a effect that is bactericidal that is similar.
Tests revealed that the perchlorate broke down into substances, chlorite and namely hypochlorite, and it is.
The scientists followed-up with another round of experiments that looked at hydrogen peroxide, which are found in Martian soil and the effects of iron oxides. These tests yielded news for Martians: the bugs were killed than with perchlorates if the bacteria were struck in the presence of peroxide, iron oxide and perchlorates with UV beams.
The findings imply that streaks might not be places to locate microbes that are alien. The patches that are briny would be inclined to focus perchlorates, making the streaks more toxic.
“I can’t talk for life before,” said Wadsworth. “As far as current life, it does not rule it out but probably means we should search for life underground where it is protected from the harsh radiation environment on the surface.”
From a Mars exploration viewpoint, he said the results were equally bad and good news. On the other hand, it means that any microbes that hitch a ride will be destroyed relieving concerns about contaminating a world that is inhabited. “This should greatly reduce planetary protection concerns in addition to any concerns about illness of astronauts,” he said. “However, the bad news is that means we must dig to quite some depth to reach a biological record of ancient life that’s not completely destroyed by the reactive UV-activated perchlorates.”
In 2020, the European Space Agency plans to ship its ExoMars rover on a mission to look for life into the planet. The rover comes with a drill which can bore two metres to the ground to retrieve soil samples in.
Andrew Coates, a scientist at UCL who directs the ExoMars camera team, said the job proves that the surface of Mars now is much more hostile to life than believed. “This, along with the solar and galactic particle radiation environment in the Martian surface, makes it even more important to sample beneath the surface in the search for biomarkers,” he said.
“With the ExoMars rover, we’ll drill to recover and analyse samples from around 2m below the surface,” he added.