As the two-year landing anniversary of NASA’s Perseverance rover and its small scouting helicopter Ingenuity draws near, the pair continue to explore Jezero Crater and unlock the many secrets of the red planet.
Perseverance recently completed a significant milestone as part of an effort to one day return Martian samples to Earth. Meanwhile, Ingenuity continues to defy all expectations as it flies and scouts areas of interest for Perseverance to explore.
Perseverance’s Sample Depot
Over the last five weeks, Perseverance has dropped 10 sample tubes in an area known as Three Forks. The samples, which were deposited onto the surface inside small, titanium tubes, include a variety of geologic and atmospheric samples of Mars that the rover has so far collected.
On Dec. 21, 2022, Perseverance deposited its first sample onto the Martian surface. Doing so required use of the rover’s sampling and caching system to retrieve the sample from within the rover.
The system then dropped the sample tube from underneath the rover, where it fell approximately 0.9 meters onto the Martian surface.
The rover then used its Wide Angle Topographic Sensor for Operations and eNgineering (WATSON) camera, located at the end of its robotic arm, to verify the sample tube was in the correct location and position.
During testing on Earth, engineers at the Jet Propulsion Laboratory (JPL) found there was a very small chance — less than five percent — that a sample tube could land vertically instead of falling to its side, which would prevent it from being retrieved.
In such a case, Perseverance would use its robotic arm to gently knock the sample tube over. This contingency operation was not needed as all 10 samples were deposited nominally.
The first sample deposited onto the surface, named Malay, is a core of igneous rock collected from the South Séítah region in Jezero Crater. Malay measures 3.07 cm (1.21 in) in length and was the seventh sample obtained by Perseverance, collected on Jan. 31, 2022.
Once the rover confirmed the sample was dropped in the correct location and orientation, Perseverance made a short drive to the second drop-off location. Each sample tube has so far been deposited approximately five to 15 meters apart to ensure ample distance between each sample for future retrieval operations.
Mageik, the second sample, is a sedimentary rock core taken from the Delta Front region and is one of Perseverance’s latest samples — being collected on Nov. 16, 2022. It is larger than Malay, measuring 7.36 cm (2.90 in), and was the 15th sample collected by the rover.
Perseverance then deposited five more samples: Crosswind Lake, Roubion, Coulettes, Montdenier, and Bearwallow.
Crosswind Lake was the first regolith sample collected (Dec. 7, 2022) and comes from a sand ripple named Observation Mountain. Perseverance had to use a different drill bit compared to other samples for the regolith collection.
The regolith drill bit features a spike-shaped structure, in contrast to the flat drill bits for rocks. Once the regolith drill bit is installed, the rover places the drill into the sand ripple and rotates the bit, allowing the loose sand grains to fall into and collect inside the drill bit.
Crosswind Lake is thought to be made up of a mix of sedimentary and igneous grains and measures 5.30 cm (2.09 in) in length.
Meanwhile, the Roubion sample represents the first atmospheric sample collected by Perseverance. Of the 43 sample tubes the rover carries, five are called “witness tubes,” which are opened to the Martian atmosphere around the rover before being sealed.
Conversely, the Coulettes and Montdenier samples contain igneous rock core samples, with Coulettes’ measuring 3.3 cm (1.30 in) and Montdenier’s measuring 5.98 cm (2.35 in) in length.
The seventh sample deposited was a sedimentary rock core named Bearwallow, which measures 6.24 cm (2.46 in) in length.
The eighth sample, Skyland, is another sedimentary rock core that measures 5.85 cm (2.30 in) in length. This deposit was followed by Atsah, an igneous rock core collected at Octavia E. Butler Landing, the name given to Perseverance’s landing site.
After Atsah, only one sample for this drop depot remained: Amalik WT, another witness tube atmospheric sample similar to Roubion. Amalik WT (the “WT” standing for “witness tube”) was collected at Amalik, the same location the Mageik sample was collected from.
In total, Perseverance has collected 18 samples, 10 of which have now been deposited onto the Martian surface in the Three Forks region. The remaining eight tubes will stay inside Perseverance, with teams planning to have the rover deliver those samples directly to the Sample Retrieval Lander — a future Mars lander that is part of the Mars Sample Return (MSR) mission.
The MSR Sample Retrieval Lander will carry the Mars Ascent Vehicle (MAV) and two Sample Return Helicopters to potentially retrieve the samples dropped on the surface.
The Sample Return Helicopters would be based on Ingenuity’s design. However, they would not be exact copies, as recent concept images show the helicopters with four small wheels at the end of their landing legs.
This would allow them to land and then maneuver over to the sample tubes to pick them up instead of having to perform pinpoint landings over each sample.
However, the current plan might not require them if Perseverance, which has retained the prime samples, can deliver them to the lander itself. In short, the dropped samples are backups in case the primary plan to directly deliver the cached samples in Perseverance to the lander should fail.
Conversely, if a dropped sample is later found to be of high value, the helicopters would then go retrieve them. Alternatively, mission planners could still decide to collect some or all of the deposited samples in addition to Perseverance’s cache.
The Mars Sample Return lander will then place the collected samples inside the MAV, which will then be launched into Martian orbit for a return to Earth via a European Space Agency (ESA) orbiter.
The Mars Sample Return mission will be split into two launches, currently targeting autumn 2027 and summer 2028, respectively, with the samples returning to Earth in 2033.
With winter underway in Jezero Crater, Ingenuity continues to grapple with reduced amounts of sunlight reaching its solar panel, resulting in low amounts of energy to use for flights. As such, the helicopter has had to divert a majority of its power to internal systems, such as heaters and electronics to prevent them from freezing.
These conditions have led to recent flights being shorter than ones conducted earlier in Ingenuity’s mission.
This hasn’t stopped the little helicopter that could, which continues to defy all expectations and fly regularly two years into its mission — a mission originally expected to survive only five flights.
As of publication, Ingenuity has completed 41 flights — traveling over 8,000 meters and accumulating a total flight time of approximately 67.7 minutes. With the technology demonstration phase of its mission complete, Ingenuity’s primary purpose now is to scout areas of interest on the Martian surface that Perseverance can explore in extreme detail.
On Aug. 6, Ingenuity performed a low-speed, 50-rpm spin test of its rotor blades, followed by a flight-like spin test of 2,573 rpm on Aug. 15, to ensure the craft could still fly in the winter conditions. After successfully performing both tests, Ingenuity performed a short hop test, rising vertically five meters (~16 feet) and translating just two meters (-7 feet) sideways in 33.3 seconds.
In September, Ingenuity completed three flights, covering a total of 302 meters (990 feet), with an elapsed flight time of 166.1 seconds. During its 33rd flight, however, a piece of foreign object debris (FOD) was spotted on one of its landing legs. The debris was dislodged during the flight and did not damage the craft.
Ingenuity would not fly again until Nov. 22, 2022, due to a major software update that gave it the ability to use hazard avoidance upon landing, as well as the ability to use elevation maps of the Martian surface to help it navigate in-flight.
Past flight software lacked these elevation maps, and could only assume the craft was flying over flat ground. As Ingenuity and Perseverance explore Jezero Crater’s ancient river delta, the new software will prove extremely useful when landing on the rough and rigid terrain of the delta.
Cheers to a successful Flight 41 🎉
Ingenuity took to the Martian skies to provide an aerial view of the area for the @NASAPersevere team. The #MarsHelicopter’s out-and-back flight covered 600 feet (183 meters) in 109 seconds. https://t.co/7DMHj9LkNX pic.twitter.com/UuosDQMCup
— NASA JPL (@NASAJPL) January 31, 2023
Given the hefty software update, Flight 34 was a short hop, flying five meters (16 feet) before landing back in the same spot. The total flight time was just 18.3 seconds and was primarily a test of the helicopter’s compatibility with the new flight software.
The next two flights saw Ingenuity move out over the many sand ripples that populate the bottom of Jezero Crater’s delta, before returning to the airfield it originally took off from.
From there, two additional flights brought Ingenuity closer to the river delta and served as additional software tests.
In addition to Ingenuity’s direct application to the forthcoming Mars Sample Return Helicopters, the prolonged life and flight time of the technology demonstrator is greatly aiding another NASA mission: Dragonfly.
Dragonfly is an upcoming quad-copter scientific research mission to Saturn’s moon Titan that will permit the science lab to fly — instead of drive — to its various scientific investigation sites.
(Lead image: Perseverance takes a selfie with the ninth sample tube, Atsah, deposited onto the Martian surface. Credit: NASA/JPL-Caltech/MSSS)