NASA’s Perseverance rover is currently exploring the carbonate rim of Jezero Crater on Mars as its extended mission.
Its primary mission was designed to last one Mars year – or 687 Earth days – beginning with its successful landing on Mars on Feb. 18, 2021. It reached that milestone on Jan. 6 this year.
We last reported the rover’s progress in the February 2023 AAPG EXPLORER. As of Nov. 1, Sol 959, Perseverance has traveled 13.8 miles and drilled 23 core samples out of 38 total sample tubes for the entire mission. The rover has returned more than 564,000 raw images that are publicly available in the mission multimedia catalog.
Since caching samples in January, while climbing up the delta from the delta margin, Perseverance drilled Cores 19-21 on March 30 (Sol 749) at Melyn, on June 23 (Sol 832) at Otis Peak and Sept. 15 (Sol 913) at Pilot Mountain. These core samples, to be returned to Earth for detailed analyses in special labs, are the prime data bonanza of the Perseverance Mission.
Extended Mission
Perseverance has been exploring a narrow band of carbonates along the inner edge of Jezero’s western crater rim. The science rover reached the carbonate unit in mid-September 2023 at Mandu Wall. Getting there was a challenge with Perseverance making multiple attempts to traverse a path of about 350 meters through a field of boulders.
The carbonate rock unit was a key factor in selecting Jezero as the landing site for exploration. On Earth, some carbonates form in the shallow areas of freshwater or alkaline lakes. The hypothesis suggests that this could also be the case for the margin carbonate unit on Mars, speculating that more than 3 billion years ago, a lake in Jezero Crater might have reached its shores, depositing the carbonate layer. Another hypothesis suggests the formation of carbonates through mineral carbonation, wherein silicate minerals like olivine react with carbon dioxide and transform into carbonates.
Carbonates are fascinating for various reasons. Firstly, they provide insights into Mars’ ancient atmosphere. These minerals develop through chemical reactions initiated when carbon dioxide from the atmosphere reacts with liquid water. Thus, studying the presence, abundance and isotopic composition of these carbonates could help infer Mars’ historical atmospheric carbon dioxide levels and provide information about its climatic past.
Secondly, carbonate minerals serve as an excellent medium for preserving traces of ancient life if it existed. When carbonates precipitate early in the rock-forming process, they can capture a snapshot of the environment, including potential signs of microbial life. On Earth, carbonate minerals have been observed to form around microbial cells, encapsulating and effectively turning them into fossils. This preservation is significant because once an organism is enclosed in carbonate, it can endure for an extended period. Stromatolites, layered structures formed by microbial colonies in mineral-rich waters, are an example of carbonate fossilization on Earth, and represent some of the earliest evidence of life.
This fourth phase of the Mars 2020 mission is anticipated to span around 230 sols, equivalent to approximately eight Earth months. During this phase, Perseverance will traverse the marginal carbonates and ascend to the rim of Jezero Crater, pausing to perform remote and proximity science observations and drill up to four cores. Data collected by SHERLOC, PIXL, and SuperCam instruments will help the science team select drill sites. SHERLOC employs cameras, spectrometers, and a laser to detect organics and minerals that have undergone changes in watery environments, potentially indicating past microbial life. PIXL has an X-ray spectrometer to identify chemical elements on a small scale. SuperCam employs a camera, laser and spectrometers to identify the chemical and mineral makeup of spots as small as a pencil point, from a distance of more than 20 feet.
To date, two core samples have been drilled in the carbonate unit. Core 22 was drilled at Pelican Point on Sept. 25, 2023 (Sol 923). Core 23 was drilled at Lefroy Bay on Oct. 21 (Sol 949). Next, Perseverance exploration will continue with an approximately one-kilometer drive northward toward Jurabi Point.
What renders Jurabi Point scientifically intriguing? It is a convergence point for three distinct geological units. Precisely, it is the juncture where the boulder-rich unit, upper fan sedimentary rock and margin unit intersect. Exploration of the interfaces between these three units aims to elucidate their chronological relationships, providing an opportunity for further examination and potential sampling of a boulder following the previous unsuccessful attempt.
Following the comprehensive study at the Jurabi Point, the trajectory will shift westward, documenting variations in the margin unit with the ascent. The Margin Campaign will culminate with a descent into Neretva Vallis (channel feature at the northeast corner of the map) for the first time – a river channel supplying the western fan. The objective is to investigate a puzzling light-toned rock unit exposed within the channel wall.
Ingenuity Helicopter Completes Flight 64
In the update in the January 2023 EXPLORER, we reported that the Ingenuity Mars helicopter completed Flight 38 on Dec. 24 (Sol 656). Ingenuity just completed Flight 64 on Oct. 27 (Sol 955). Ingenuity was originally designed to make five flights in a 30-day demonstration of its capability as an exploration partner to the Perseverance rover. It has far exceeded expectations and joined Perseverance as an exploration companion in the climb to the delta top in the extended mission. Ingenuity has flown a total of 9.3 miles with a total of 118 minutes of flight time.
Reassessment of Mars Sample-Return Mission
The Mars Sample-Return Mission was planned for the 2026 or 2028 launch windows to return Perseverance drill core samples to Earth around 2033. In July, the Senate Appropriations Committee requested a budget breakdown for MSR that fits into the original $5.3-billion lifecycle cost outline or the MSR Mission could be cut from the budget. NASA is postponing the progression of the MSR program’s next development phase due to significant issues identified in an independent review related to technical readiness, cost and schedule.
The final report of this review, released on Sept. 21, was conducted by an independent review board chaired by Orlando Figueroa, the former director of Mars exploration at NASA. The board found the current MSR architecture to have an “unrealistic” budget and schedule, estimating a “near-zero” probability of the sample retrieval lander and Earth return orbiter being ready for the planned launches.
The projected costs for MSR were also evaluated to be between $8 billion and $11 billion, exceeding previous NASA projections. Responding to these findings, NASA has initiated a revision of its Mars sample-return approach and formed the Mars Sample-Return IRB (independent review board) Response Team. The MIRT, established to address the recommendations from the IRB, aims to develop a revised Mars sample-return architecture by March 2024.
The team, formed with various subcommittees focusing on technical, scientific, programmatic and budgetary aspects, faces the challenge of uncertain funding for MSR in fiscal years 2024 and 2025 amid broader debates on agency funding. The maturity of the orbiting sample design, a critical component launched into orbit by a Mars ascent vehicle rocket and captured by the Earth Return Orbiter, was identified as a key issue by Figueroa. To address this, one proposed alternative involves reducing the number of samples returned, potentially leading to a smaller and more cost-effective orbiting sample design.
The team will generate two or three alternative mission architectures by March 2024. After NASA chooses a new design, the space agency will officially commit to the program’s cost and schedule, aiming for a confirmation review by late 2024.
The IRB report did underscore the importance of the mission: “A successful MSR campaign will revolutionize our understanding of the history of Mars, the solar system, and the potential for life beyond Earth.”
Is was also recommended that NASA remain committed to Mars sample return despite its current problems: “MSR is clearly, logically the next step in our leadership on Mars,” said Sandra Connelly, NASA deputy associate administrator for science. “It does remain a NASA priority.”
NASA is proceeding with its initiative to bring back Martian samples, ensuring it doesn’t adversely affect other scientific pursuits within the space agency.
Curiosity Rover Update
NASA’s Curiosity Mars rover is steadily climbing Mount Sharp in Gale Crater. On Jan. 28, 2023 (Sol 3725), the rover discovered a rock from space, namely an iron meteorite. On Aug. 9, (Sol 3913), the Curiosity rover identified well-preserved ancient mud cracks, indicating recurring cycles of wet and dry conditions over extended periods. The rover was drilling a rock named Pontours, sandwiched between a clay-rich layer and another layer enriched with salty sulfates. This discovery represents the initial evidence of such wet-dry cycles on Mars. The rover made this finding in a transitional area between regions rich in clay minerals and sulfate minerals. The mosaic captured by Curiosity’s Mastcam on June 20, 2021, consists of 143 images stitched together, revealing hexagonal shapes reminiscent of those in Earth’s locations like Death Valley National Park’s Racetrack playa. These shapes, formed after years of alternating wet and dry periods, undergo distinctive transformations in their angles and ridges as the mud cracks evolve through rehydration and erosion processes.
The identification of wet-dry cycles is particularly intriguing for Curiosity’s scientists, as it aligns with theories suggesting these conditions might support or even be essential for the formation of life. Published studies indicate that wet–dry cycling can promote prebiotic polymerization. The process of dehydration and rehydration has the ability to transform concentrated lipid structures into thin-walled vesicles that can encapsulate RNA through polymerization reactions. This process is believed to be relevant to the formation of cellular life on Earth.
To further emphasize that we have most of the ingredients for life, In the November 2023 EXPLORER, we reported that purine and pyrimidine building blocks of RNA and DNA along with amino acid building blocks of proteins are found in 4.5-billion-year-old carbonaceous chondrite meteorites that have landed on Earth. These space rocks are similar to the carbonaceous asteroid Bennu samples just delivered to Earth by the OSIRIS REx probe. If these key organic molecules can form abiotically in the solar nebula that formed our solar system, Mars’ warmer, wetter past 3.5 billion years ago would have been a fertile place to evolve more complex organic chemistry as it did on Earth at about the same time. No doubt we will find these key organic molecules in these asteroid Bennu samples and on Mars.
In the May 2022 EXPLORER, we reported that Curiosity’s tunable laser spectrometer measurements from six sample locations found anomalously light δ13C values. Enrichment in carbon-13 on Earth is associated with biological processes. In the July 2022 EXPLORER, we reported that Curiosity’s Sample Analysis at Mars instrument found high concentrations of organic carbon in 3.5-billion-year-old lacustrine mudstones of Gale Crater. SAM analyses revealed diversity and abundance of sulfur-bearing aliphatic and aromatic organic compounds in the sediments of this Gale crater.
These discoveries underscore the value of sending the rovers to Mars to search for possible evidence of ancient life.