10 years ago, the Curiosity rover arrived on Mars and revolutionized the hunt for extraterrestrial life
Ten years ago today, NASA’s Curiosity rover touched down on Mars to identify clues that could help answer the burning question, “Is there life beyond Earth?” This mission has so far been a resounding success, and Curiosity still roams the planet’s surface today, continuing to provide data to scientists, allowing them to reconstruct the history of Mars and unravel the mystery of life. on the planet.
Curiosity was launched on November 26, 2011 from Cape Canaveral Air Force Station in Florida. It landed on Mars 10 years ago on August 5, 2012. Plans for Curiosity began long before its launch and involved hundreds of scientists from around the world.
Once Curiosity entered the Martian atmosphere, it was designed to move similarly to NASA space shuttle astronauts to the landing site. Several minutes before landing on the surface, Curiosity deployed a parachute to decelerate. An advanced system containing mounted retrorockets further slowed the spacecraft, before Curiosity descended from the lander through a tether and placed the rover upright on its wheels.
Curiosity landed at Bradbury Landing at the base of a giant mountain, Aeolis Mons, meaning Sharp Crater, with an elevation of 18,000 feet, making it higher than any mountain in the contiguous United States. Aeolis Mons resides inside Gale Crater, a 96-mile-wide crater that dates back to the early formation of Mars 3.8 to 3.5 billion years ago as the product of a comet or a meteor hitting the surface of the planet.
Emily Lakdwalla, planetary geologist and author of TThe design and engineering of Curiosity: how the Mars rover does its job and scientific explainer (retired) for the Planetary Society who is also working on a second book, Curiosity: Scientific missionrecount Reverse that ever since the Viking orbiter identified geologic formations on Mars that were likely formed by water, Mars exploration “has been united under the mantra, ‘follow the water'”.
Water is considered a key ingredient for life on Earth. She further explains that strong Martian craters, such as we see on the Moon, may contradict the long-term presence of water. Simply put, many long-standing craters with no signs of erosion could mean the water disappeared a very long time ago or hasn’t been there for a long time.
“If you’re interested in the question of life on Mars, you need to figure out whether water was ever really stable for long,” Lakdawalla said. “If so, what kinds of environments did it exist in?” Thus, the idea of tracking water and determining the conditions under which liquid water had existed on the surface of Mars in the past was a unifying theme for Mars exploration. This has driven much of the science of missions that have taken place over the past 25 years or so.
Gale Crater was chosen after much debate due to a variety of promising indicators that there would be a water record there.
Why was Curiosity so revolutionary?
What initially differentiated Curiosity from other Mars missions, Lakdawalla says, was the desire to make a precision landing. All past missions, such as Pathfinder, Vikings, Opportunity, and Spirit, had very wide designated landing zones.
“So the next idea was sort of established by NASA headquarters saying that to really get to interesting places that we’ve found from orbit that might answer these questions about water, we need to have a more precise landing capability,” she said.
In addition to advanced landing capabilities, Curiosity is a powerhouse of a rover. Powered by a radioisotope system, Curiosity has already exceeded its planned mission duration of 23 months, or one Mars year, but it is still performing well and producing new data today.
“It was built with a lot more redundancy [than other rovers] where it has two main computer brains, two motor controllers, two pumps for its coolant, it owes two of the most important things, but it only has one of each scientific instrument,” Lakdawalla recalls.
Curiosity rover specs
The rover weighs 1,980 pounds, which is significantly lighter than a standard car (3,300 pounds). Despite its relatively light weight, NASA compares its dimensions to those of a small SUV (10 feet long by 8.8 feet wide by 7.2 feet high). It is much larger than other Mars rovers like Spirit and Opportunity. In addition to its body, Curiosity also has an arm that can reach 7.2 feet. This arm is essential for Curiosity operations because it can actually collect samples from the surface of Mars.
Curiosity carries out analyzes of rock, soil and air to determine if the planet was ever suitable for supporting life. The rover itself acts as a laboratory and is the “largest and most capable rover ever sent to Mars”, according to NASA.
Some of the tools in Curiosity’s lab include a mass spectrometer and an X-ray diffraction and fluorescence instrument that can identify the chemical composition of soils collected by the arm. The Mars Hands Lens Imager is a camera attached to the rover’s arm that can take pictures so small they would be able to image a human hair in great detail. It can also take high-resolution photos of fine materials at a distance from the lens. In fact, snippets of images of the curiosity itself have been put together in a “selfie” portrait.
“There are lots of obvious delta deposits where sediments were deposited in standing water. It shows you signs of ancient lakes or clay minerals everywhere. There is an incredibly thick succession of rocks that were deposited at the over time,” says Lakdawalla. “The mission is just going up a hill monotonously, which means you’re driving from earlier to later, so you read the story in order, so it’s very practice.
Gale Crater: a treasure trove of data
Fortunately, Curiosity scored quickly after its touchdown on the Martian surface. The rocky conglomerate near the rover’s landing site consisted of rounded pebbles and sand that were normally formed by the flow of water.
After its initial landing, Curiosity was remotely piloted to an area of Gale Crater called Yellowknife Bay. There he collected his first drilled sample of rock from Mars, called “John Klein”, which yielded exactly what the researchers had hoped for.
Chemical and geological analyzes conducted on John Klein identified the rock as the Sheepbed mudstone which was interpreted to have formed from an ancient lake. Evidence of a large body of calm water confirmed that Mars had water that was held on the surface for a long time. It contained sulfur, nitrogen, oxygen, phosphorus and carbon – all elements necessary for life as we understand it on Earth. The pH levels also indicated that the atmospheric chemistry of that time could support life. This type of rock can support the type of microbial life that would consume the energy of the chemicals in the rocks.
A second sample from Yellowknife Bay provided another first in space history. While rocks from other worlds, such as the Moon, have been dated by lab analysis on Earth, Curiosity provided the first lab age of a rock made by analysis on another planet.
Ken Farley, professor of geochemistry at Caltech, proposed using Potassium-Argon dating to date the rock itself. Some rocks contain a radioactive potassium isotope, potassium-40, which decays to argon-40, which remains stable. The isotope decays at a known rate, so the ratio of potassium-40 to argon-40 can provide an approximate age. The results showed that the rock itself was formed 3.86 to 4.56 billion years ago.
Curiosity used surface age dating, which counts the number of cosmic ray isotopes that penetrate the first few meters of a planetary surface to determine how long a surface has been exposed. Curiosity’s analysis revealed that the rock sample was only exposed at the surface 80 million years ago. Cosmic ray isotopes can degrade the quality and quantity of organic samples, but on the scale of geological time, 80 million years is not that long. It’s good for finding evidence of life on Mars.
The discrepancy between the age of the rock and the time of its recent surface exposure is attributed to wind erosion. As Curiosity witnessed in 2018 during a dust storm that covered the entire planet, dust storms on Mars are no joke. Theoretically, this information can help scientists identify better locations to collect rock samples that may be less exposed to wind erosion and therefore cosmic rays, which can break down organic matter – an important aid in the search for the life.
Although it took years of planning to bring Curiosity to Mars, part of Lakdawalla’s interest in Curiosity stemmed from the fact that, unlike other missions, she describes the nature of the Curiosity mission as being like a road trip.
“The rover mission is not planned months in advance, it is planned every day that new data comes in, to decide what to do with the rover the next day,” she explains.
For example, Curiosity spent much longer than expected in Yellowknife Bay. Lakdawalla recalls: “They were stuck there for a year. And so they didn’t start driving up the mountain [Aeolis Mons]until almost the first anniversary of their landing.
Since arriving at the Aeolis Mons base, Curiosity has been moving slowly, sampling thin layers of the geological record as it climbs in altitude and advances through the history of Mars, continuing to find promising evidence of a planet that might once have been suitable for life.
Now Curiosity is still hard at work and on its way to its next destination to collect more samples at the Aeolis Mons base. We’ll have to stay tuned to see what else he has to reveal to us in the future.
If there’s one thing Lakdawalla would like people to know about the Curiosity mission as it continues, it’s that “they can look at every photo Curiosity takes. They arrive on Earth and come out on the web as soon as they are available to the science team. It has become a tradition for Martian missions. Some other NASA missions do as well. It’s great because it means the public can follow the road trip.