One year after launch and almost six months after landing, the Perseverance rover attempted to collect its first sample of Martian rock. On August 6, it extended its robotic arm towards an intriguing rock chosen by scientists and whirred up a specialized drill bit. If all went well, there would soon be a small hole in that rock, and a core sample would be safely stowed away onboard Perseverance.
Everything went as planned.
Everything went as planned.
Perseverance's drill worked flawlessly and made a clean cut into the target rock. Scientists were able to confirm this with an image of the drill site that showed a clear, cylindrical hole that penetrated deep into the rock surface. However, success was fleeting. Even though the rock indicated that a sample had been taken, there was a slight problem.
The rock core was missing.
It wasn't stored inside the drill or stowed away on the rover, and the discrepancy between this discovery and the image showing a successful drill bewildered scientists. However, it didn't take long for scientists to form a plausible hypothesis. It was unlikely that the drill had malfunctioned, as it had undergone countless rounds of testing here on Earth, so the problem most likely originated in the sample, and not the sampling system. This line of thinking led the scientists to eventually determine that while the rock core was being removed from the target site, it had crumbled into dust and escaped from the drill. So in essence, the problem lay with the powdery nature of the rock.
It was an intricate process years in the making, and though this particular attempt did not go exactly as planned, scientists are already planning a redo. Perseverance is moving onto a new location, and hopefully, the issue will be resolved when the next sampling attempt begins in September. Unlike previous missions that have also directly investigated samples of Martian soil and rock, there is a very real chance that humans may one day get to study Perseverance's samples with their own eyes back here on Earth. After all, the collection of rock samples is only one piece of an enormous puzzle that will gradually be put together by scientists and engineers in the coming decade. This grand plan is called the Mars Sample Return Project.
Ever since we started visiting celestial worlds, scientists have been obsessed with understanding their diverse compositions, since knowing the chemical makeup of an object can reveal details about its conditions, origins, and how it formed. As a result, space programs have sent numerous robotic spacecraft to the surfaces of places like the moon and Mars, with the main objective of analyzing the composition of extraterrestrial soil and rocks. However, most of these unmanned landers and rovers have no real means to get back to Earth, which presents an interesting problem. Because of weight and size restrictions, scientists can only pack so much equipment into these spacecraft, which limits the scope of science that can be conducted. Additionally, spacecraft carry a portfolio of tools that are built long before launch, and cannot be modified mid-flight. This means that if a spacecraft lacking a particular science instrument arrives at a distant world where a use for that instrument is later identified, scientists are pretty much out of luck.
However, with sample return missions, samples brought back from celestial bodies can be analyzed with tools on Earth that are far more advanced than those carried on spacecraft, and sometimes, they can even be studied with tools that haven’t even been invented yet at the time of launch, allowing scientists to continue gleaning more data from a sample long after a mission has ended. With the possibility of increased scientific gain combined with the added propaganda value a sample return mission could provide during the Cold War, it was inevitable that the space programs of the United States and the Soviet Union would eventually bring pieces of space back to Earth. Since then, space agencies from all over the world have attempted sample return missions. Many of these missions have targeted the Moon, like the American Apollo moon landings, Soviet Luna missions, and more recently, the Chinese Chang’e program. A separate fleet of missions has also sampled asteroids, including Japan's Hayabusa 1 and 2, and the American OSIRIS-REx mission. There was even a mission called Genesis which collected samples of ionized particles carried by the solar wind, and a mission dubbed Stardust which returned dust from the tail of a comet back to Earth! However, out of all these destinations which have hosted sample return missions, the world that is arguably the most promising in terms of scientific gain continues to elude us: Mars.
Mars sample return missions have been suggested for almost three decades, but have never made it past the planning stage before Perseverance and the Mars Sample Return Project because of issues surrounding complexity, technology, and funding, which all stem from challenges that the Martian environment poses. Although small when compared to other planets, Mars is still significantly more massive and thus has a stronger gravitational field than bodies we have already launched sample return missions to, such as the Moon or asteroids. Additionally, Mars is also on average much farther from Earth than these targets, and its atmosphere, although thin, is nothing to be trifled with. Together, these factors of gravity, distance and atmospheric resistance ensure that any spacecraft designed to travel to Mars and back will need tremendous amounts of fuel. So although Mars is a very enticing target, its environmental challenges have prevented us from attempting sample return missions, until now.
The Perseverance rover is the first step to realizing the dream of returning samples from Mars. The current plan is a collaboration between NASA and the European Space Agency, and will involve multiple spacecraft and almost a decade of waiting to solve the aforementioned challenges Mars presents. For the time being, Perseverance will continue its scientific operations, collecting samples of the soil during its mission. Over the next few years, around 40 samples will be cached and stored separately in a container that will be deposited on the Martian surface. Then, in July 2026, a lander with a dedicated "fetch" rover and Mars ascent rocket will launch and land near the Perseverance rover 6-10 months later. The rover will collect the sample container and bring it back to the lander, where it will be stowed away in the ascent rocket. At the same time as the lander launch in 2026, an orbiter designed to bring the samples home on the final leg will also be launched, which will arrive in its proper orbit around Mars in 2028. Once the orbiter is in position, the rocket awaiting on Mars will finally lift off in 2029, and the samples will undergo a final handover into a compartment onboard the orbiter. From there, the orbiter will begin its journey back to Earth, and more than a decade after the launch of Perseverance, the samples will at last parachute down into the hands of scientists in 2031.
To an outside observer, this mission would appear to be highly complex, and to the actual personnel working on it firsthand, the experience will certainly be even more nerve-wracking. Indeed, a mission of this scale has never been attempted before, and with so many interrelated steps, failure reduction will undoubtedly be front and center in the minds of mission planners.
However, if all goes well, the risks will be vindicated as the success of this mission will have countless far-reaching impacts on the future of Martian exploration. Firstly, scientists will at long last get their hands on pristine samples of Mars. Although meteorites originating from Mars have been found on Earth and closely studied, they are not considered to be accurate representations of the Martian environment as it is today, or as it was billions of years ago. Perseverance, on the other hand, is studying Jezero Crater, which is believed to have hosted a lake and a river delta in the distant past, so samples from that region will allow us to study the composition and history of Mars in ever-greater detail with Earth-based instruments. Additionally, Martian meteorites have encountered terrestrial contamination through millions of years of exposure to our planet, which is a roadblock if you are trying to determine whether life ever existed on Mars. Returning pristine samples from the red planet, especially from a place where life could have flourished, will greatly benefit our quest to answer the age-old question "Are we alone?"
But even then, a successful sample return mission will mean so much more for things like the eventual human exploration of Mars, since it will act as a testbed for technology that is vital to this goal. For instance, taking off from another planet has never been attempted before, and signals from Earth can take several minutes to get to Mars, so if it is successful, this mission will demonstrate the technologies needed to get off of the planet, enter orbit, and perform an orbital rendezvous without any input from Mission Control on Earth whatsoever. Therefore, a sample return mission to Mars is a requirement to ensure a safe voyage when humanity breaks its Earthly bonds and takes its first steps on the red planet. Who knows, maybe we will become the life on Mars that we have spent so much time searching for.
Perseverance is not the only spacecraft that is preparing for a future sample return mission from Mars, as the space agencies of China and Russia also have mission plans of their own, both of which are planned to launch in this decade. Regardless of what happens next, another chapter in the exploration of our neighbouring planet is being written before our eyes, and this chapter may provide us with answers to questions that we haven't even dreamt of.
Mars has enchanted astronomers and scientists alike since ancient times, and even now, after thousands of years gazing upon that red dot in the sky, we have only begun to scratch the surface of the secrets that lie on and within Mars.