Searching for signs of life on Mars: Trailblazer finds a clue to finding biological imprints

“Trailblazer’s mission is to collect samples that will be returned to Earth for the research team to explore to see if life once existed on Mars and if it left a “biological footprint.

The latest issue of Science published the first paper on the results of the Trailblazer survey, describing the rover’s findings in Jezero Crater – an ancient delta-lake system and flood deposits.

The sediments at the bottom of the lakes usually hold traces of ancient aquatic life.

“One of Trail’s main tasks is to collect samples from the sediment layers on the rim of Jezero Crater, which will be returned to Earth for the research team to explore and identify whether life once existed on Mars and whether a “biological imprint” was left.

Jonathan Amos, BBC science and technology correspondent, said the analysis confirmed that the Mars rover site was once the bottom of a large lake with an estuary on the west side where a meandering river fed into the lake; that would have been 3.7-3.5 billion years ago, when the climate of the red planet was much milder.

By analyzing the image data returned from Mars, the scientists concluded that the dry, barren, wind-eroded basin was still a lake when the mouth of that river formed an alluvial delta.

The site images also show that the river in the Crater Lake system had a severe flood, probably at the end of the lake’s history, powerful enough to wrap boulder sediment in a raging torrent all the way into the lake from dozens of miles upstream. The boulders sank to the bottom of the lake and have been there until now, when they have been discovered by humans.

Previously, scientists inferred from images taken from Mars orbit that the western side of Jezero Crater resembled a river delta on Earth, and Trailblazer took the first field images of the exposed rocks there, confirming the trail.

Image credit, ESA/DLR/FU BERLIN

Image annotated with text.

Information has been obtained that indicates there was once a large amount of liquid water on the surface of Mars.

Based on the analysis of flooded sediment layers, scientists infer that the lake was mostly calm until a dramatic change in climate triggered a huge flood. Researchers hope to find more clues that will reveal the evolution of the climate there.

On Feb. 18, 2021, Trail touched down at the bottom of Jethro Crater as NASA engineers operated remotely from Earth Control to check and tune many of the instruments on the rover. During this time, the rover remained stationary, but the two cameras on board did not stop working and continued to take pictures of the surrounding environment and landscape.

The video of these images was transmitted to Earth, processed, combined, and detailed at very high resolution to examine the different sedimentary layers along the Kodiak formation, measuring the thickness of each layer, the lateral extent of the slope river, and then comparing them with images of sedimentary layers in other sections along the crater to reach a final conclusion.


The Trail Rover landing site is one or two kilometers southwest of the main deltaic zone

They concluded that the sediments at this site were formed through water deposition and determined that this was once a delta at the confluence of a river and lake, rather than a sedimentary layer formed through wind or sheet flooding and their geological processes.

Another surprising discovery was the large boulders and cobbles embedded in the top layer of the deltaic sediments, the largest of which was one meter wide and weighed an estimated ton. The team believes that these boulders were carried into the crater by some force, most likely from the crater rim or from upstream 40 miles or more from the river’s entrance.

Based on the analysis of where the boulders are now located and their size, the current that washed the boulders into the lake at speeds as high as 9 m/s is embedded in the top of older, finer-textured deltaic sediments, suggesting that they were deposited at a later date.

In other words, the sediment and fine gravel from a river that fed into the lake was continuously deposited to form the delta, and then one day a flash flood broke out upstream and washed the boulders into the mouth of the lake, where they were deposited in the delta and wind eroded over billions of years to form the present-day appearance.

Image annotated with text.

Illustration of the geology of the Kodiak massif: top deposit, front deposit, bottom deposit

Scientists hope these deposits will help mankind uncover what happened to Mars long ago, how the climate changed and how it caused the sea to dry up.

Professor Sanjeev Gupta of Britain’s Imperial College London is one of the lead authors of the paper in the journal Science.

He told BBC News that the analysis showed “some changes in the hydrology there, but whether they are climate-related, we don’t know.”

He explained that “moving these boulders would require something like a flood (of great energy). Maybe there’s a glacial lake upstream and the flood water drains into Jezero.” He told BBC correspondent Amos that on Earth, you can see lakes breaking up in places like the Himalayas, and you can see these large boulders mixed with normal river sand in the Ganges basin, and that’s where the glacial lake burst into flood.

“The Trailblazer science team will send the rover to the base of the main deltaic strata to drill in what is estimated to be fine-grained mudstone.

They will also explore a ring of carbonate rocks around the rim of Jezero Crater, which may have been the shore of the volcanic lake at its deepest point.

If there is any significance in studying the sediment stratigraphy of the estuarine delta of Jezero Crater, the first thing that should be hoped for is that this will uncover changes in climate, rivers, and environment during the period before the lake dried up.

This is a clue as to where the exploration should be focused first and at what level of the sediments. “After eight months of roving on Mars, Trailblazer has found clues to the search for signs of life, and the next step in the exploration will no longer be aimless, but will focus on digging deeper in the identified sites.