On February 18, 2021, NASA’s Perseverance (Percy) Rover successfully landed in the dried-up lakebed known as Jezero Crater on Mars, beaming back images and video of its descent and landing to millions of space fans living on the planet that built and launched this incredible robotic explorer. With this landing came enormous excitement for a new era of robotic exploration of the Red Planet as we slowly continue to unlock the secrets of Mars and its ancient past, to include (hopefully) finding evidence of past life.
While Mars might have once featured a lush and habitable environment, today it’s nothing more than a cold, dead world. With an average surface temperature of -63°C (-82°F) and an atmosphere consisting of 95% carbon dioxide and pressures that are 100 times less than Earth’s, the Mars of today is incredibly inhospitable for life as we know it here on our blue marble in space. This extremely harsh environment hasn’t stopped us from trying to unlock Mars’ secrets and learn more about how it came to be what it is today, with Percy working literally tirelessly to continue this incredible scientific journey.
During its venture on Mars, Percy collected eight rock-core samples during its first science campaign and completed a record-breaking 31-Martian-day (sol) trek across 5 kilometers (3 miles) of Mars. It ultimately arrived at the doorstep of Jezero’s ancient river delta on April 13, 2022. This delta is significant as it will not only serve as Percy’s staging area for its second science campaign, known as the “Delta Front Campaign”, but is also believed to be the mission’s best bet in finding preserved remnants of ancient microbial life.
The delta, a massive fan-shaped collection of rocks and sediment at the western edge of Jezero Crater, formed at the convergence of a Martian river and a crater lake billions of years ago. Its exploration tops the Perseverance science team’s wish list because all the fine-grained sediment deposited at its base long ago is the mission’s best bet for finding the preserved remnants of ancient microbial life.
“We’ve been eyeing the delta from a distance for more than a year while we explored the crater floor,” said Ken Farley, Perseverance project scientist at Caltech in Pasadena. “At the end of our fast traverse, we are finally able to get close to it, obtaining images of ever-greater detail revealing where we can best explore these important rocks.” Having officially kicked off on April 18, 2022, the Delta Front Campaign will instruct Percy to drive to the southwest and then to the west. The goal of this first leg will be to scout the best route to ascend the delta, which rises about 40 meters (130 feet) above the crater floor.
The Delta Front Campaign is scheduled to take about half an Earth year, during which time Percy will be conducting detailed science investigations while on the way up the delta, and on the way back down, as well. These investigations include taking rock core samples, and Percy is expected to collect around eight samples during this time.
“The delta is why Perseverance was sent to Jezero Crater: It has so many interesting features,” said Farley. “We will look for signs of ancient life in the rocks at the base of the delta, rocks that we think were once mud on the bottom of ‘Lake Jezero.’ Higher up the delta, we can look at sand and rock fragments that came from upstream, perhaps from miles away. These are locations the rover will never visit. We can take advantage of an ancient Martian river that brought the planet’s geological secrets to us.”
As stated, Jezero Crater on Mars is a dried-up lakebed believed to once be the home of a massive amount of liquid water deep in Mars’ ancient past. The crater itself has a diameter of 45 kilometers (25 miles) and is located in the Syrtis Major quadrangle. Aside from the delta that is located in the western part of Jezero, the crater also displays point bars and inverted channels, other evidence that liquid water once existed there long ago.
Ancient Past: A Wetter, Warmer Mars
When Mars first formed billions of years ago, its interior was searing with heat and a spinning outer core. This spinning outer core gave Mars a magnetic field, shielding it from the intense cosmic radiation from the Sun. This magnetic field allowed auroras to dance across the night sky in breathtaking fashion, much like what we see near the poles on present-day Earth. This interior heat also fueled the many volcanoes spread across the surface to replenish the atmosphere just like what happens on present-day Earth, giving Mars a much thicker atmosphere and allowing liquid water to cascade across its surface, carving out channels and streams, and even filling many craters also strewn across its vast surface. Alas, with Mars being half the size of Earth, physics intervened, and the Red Planet slowly died from the inside out due to the loss of heat. When you put potatoes in an oven and remove them some time later, the smaller potatoes cool off much faster than the larger ones, and this cooling was the unfortunate fate for Mars. With the loss of heat, the volcanoes ceased to replenish the atmosphere and the magnetic field slowly faded away. Losing these two key atmospheric components caused the once cascading liquid water to slowly evaporate, leaving us with the cold, dead world we see today.
What secrets will Percy unlock about the ancient past of Mars? How long was liquid present on the surface, and will this car-sized rover find evidence of past life on the Red Planet? Time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Source: NASA JPL
Lead image: The expanse of Jezero Crater’s river delta is shown in this panorama of 64 stitched-together images taken by the Mastcam-Z system on NASA’s Perseverance Mars rover on April 11, 2022, the 406th Martian day, or sol, of the mission. (Credit: NASA/JPL-Caltech/Arizona State University/Malin Space Science Systems)