If you have an interest in planetary exploration, you might want to get yourself online this Thursday, February 18. NASA’s Perseverance rover is set to land on Mars around 3:55 PM Eastern (2:55 PM Central, 12:55 PM Pacific). If the landing is successful, this will be a big deal, as this rover comes equipped with the tools to detect past life on the planet. The rover also carries the first aircraft to be used on another celestial body--a small helicopter called Ingenuity--which will be used to test the feasibility of flight in the very thin Martian atmosphere.

The Landing, Ingenuity, and Collecting Samples

The lander will utilize the “sky crane” landing technique that the most recent rover, Curiosity, used to arrive on the planet. A good animation of how this works, using a heat shield, parachute, a retrorocket vehicle, and a lowering cable crane can be seen here:

Perseverance Landing Animation

Soon after landing and activating, Perseverance will lower the Ingenuity from its belly and move away from above the helicopter. Up to 5 flights are planned, with the basic goal just to prove flight is possible on Mars (the atmosphere of Mars is only about 1% the density of that of Earth’s, making it very challenging to get any lift). With a little luck, Ingenuity will also get some images and videos. An overview of its mission can be seen here:

Ingenuity Details and Animation

Perseverance will be landing in an ancient river delta that flows into Jezero Crater. The delta is shown in the photograph below. The crater is quite large, taking up the majority of the center and right-hand side of the image, the edge of the crater being the ridge of mountains that is shown curving slightly from the top to the bottom of the photograph. A river of water to the left side surged through the mountainous edge of the crater about 3.5 billion years ago, forming the delta.

You can see the delta that formed through the wall of the crater 3.5 billion years ago in the image above. --NASA/JPL-CalTech

Of course, water is necessary for life as we know it. Landing here, with a rover that has science tools to detect past life, is our first real chance to find it.

Perseverance has an additional mission to collect 20 or more samples of Martian rock and dirt that will be hermetically sealed and stored in 43 sample containers in the belly of the rover. At a time and place of the science team’s choosing, these will be deposited at a location (or locations) on the surface of Mars, to be picked up by future robotic spacecraft to return to Earth, which are due to launch in coming years. We have never had direct and untarnished samples from Mars to examine in laboratories here on Earth, and especially never had them coming from locations that used to have water, and which could possibly contain evidence of past microbial life.

Perseverance Sample Collection Animation

Building on Missions of Previous Rovers

There have been other rovers on Mars. Sojourner spent 3 months on Mars back in 1997 (the smallest rover in the image below); Spirit and Opportunity both landed in 2004 and spent an amazing 6 years and 14.3 years, respectively, investigating the planet (both are represented by the middle-sized rover to the left in the image below); and Curiosity landed in mid-2012 and is still operational on Mars (the largest of the rovers to the right in the image below). Perseverance is the same size and has the same framework as the Curiosity rover, but with different instruments and a different scientific configuration.

Rover sizes. --NASA

These rovers, along with other landers and orbiting spacecraft, collectively have discovered a ton about Mars over the past couple of decades, and its potential to have had microbial life in the distant past--or even possibly right now.

Sojourner Rover

Spirit and Opportunity Rovers

Science from Spirit and Opportunity

Curiosity Rover

Science Timeline for Curiosity

Water and Organics

First is evidence of water. It is everywhere on Mars. The Spirit and Opportunity rovers found polished spherical stones that almost certainly were altered by liquid water on the surface in the distant past. These rovers also found areas where olivine and sulfates exist together on the surface of Mars. Interstingly, where there is less olivine on the ground, there is more sulfate, and vice versa. When water is present, it destroys olivine and produces sulfate from its interaction, and this is exactly the geological layout that would be expected if there had been a thin layer of water on the surface in the ancient past.

The Curiosity rover found direct evidence of water--both present and in the past. Water was detected directly in the Martian “soil” at multiple locations at very low levels (1.5%-4% of molecules in the samples). Also, direct evidence of an ancient freshwater lake was found.

Curiosity also discovered large amounts of organic compounds on Mars, such as chlorobenzene in some of the soils and a large outburst of methane in the atmosphere. Organic compounds (chemical compounds with carbon-hydrogen bonds) like these are thought to be needed for life as we know it to arise, and this becomes more possible when water (the source of hydrogen) is a part of things.

Strange gray formations on top of a rock that the Curiosity rover examined in 2018 and in the surrounding dirt. Are these geological or biological? Probably geological, but we currently can’t say for certain. --NASA

Other non-rover spacecraft in orbit around Mars have discovered huge amounts of water on the planet, both in the form of ice on the ground, and both ice and liquid water beneath the surface. Enough water has already been detected on Mars to cover the entire planet with an ocean 115 feet (35 meters) deep, and there is undoubtedly more laying undetected beneath the surface.

Much of the discovered water is stored in the north polar ice cap which is just about exclusively water ice. Additional water ice has been found below the carbon dioxide ice cap at the southern pole. In 2018, amazingly a liquid water lake 19 miles (30 km) long was detected 1 mile (1.5 km) below the southern ice cap, alongside 3 other smaller liquid water lakes.

It is theorized that 3.8 billion years ago, an ocean covering more than one-third of Mars (36%) may have existed.

Evidence of Water on Mars

Where and When to Watch the Landing

Now that both water and organic compounds are known to exist on Mars, the prerequisites for life having arisen are definitely there. So, let’s see what Perseverance can detect and discover!

On Thursday, coverage of the landing will start around 2:15 PM Eastern (1:15 PM Central; 11:15 Pacific) at either nasa.gov (hopefully there’ll be a link on the front page, but if not look for NASA TV) or go to YouTube and search for Perseverance Landing and look for a live link (there will probably be several).

NASA Perseverance Mission Site

Perseverance Rover