Mars Sample Return science continues amid budget uncertainty

THE WOODLANDS, Texas — Efforts by scientists to use a Mars rover to collect samples are continuing even as NASA wraps up a new assessment of when and how those samples will be brought back to Earth. The Perseverance rover, which landed on Mars in February 2021, has filled 26 of its 43 sample tubes, scientists involved with the mission said in presentations at the Lunar and Planetary Sciences Conference (LPSC) here March 12. The rover is climbing up the remains of a river delta that once flowed into Jezero Crater. Of those 26 tubes, 20 contain rock cores, said Meenakshi Wadhwa, a planetary scientist at Arizona State University who serves as principal scientist for Mars Sample Return (MSR) at the Jet Propulsion Laboratory. Two contain regolith and another holds a sample of the atmosphere, while the other three are “witness tubes” that serve as controls to identify any terrestrial contamination in the other tubes. Two of the remaining 17 tubes are also witness tubes, leaving 15 that can be filled with other samples. Scientists are planning next phases of the rover’s traverse, she said, such as to the crater rim, which promises what she called “an incredible diversity” of rocks of different ages and exposed to different processes, “including materials of astrobiological potential.” That work is ongoing as NASA enters the final phases of a review of the overall MSR architecture, including the schedule and design of the mission that will collect those sample tubes and return them to Earth. After an independent review board, or IRB, concluded that the agency’s existing approach could not meet cost and schedule goals, NASA commissioned an MSR IRB Response Team (MIRT) in October to evaluate alternative approaches.

A sample tube on the Martian surface in the shadow of the Perseverance rover. Perseverance is continuing to collect samples as NASA develops a new plan for returning them to Earth. Credit: NASA/JPL-Caltech

“Much of the work is already complete” by the MIRT, Wadhwa said. The MIRT is expected to complete its work by the end of the month, with NASA releasing its revised MSR plans, and proposed budget, as soon as April.

That has put not just MSR but also NASA’s overall planetary science portfolio in limbo. NASA’s fiscal year 2025 budget proposal, released March 11, left MSR funding as TBD, or to be determined. At the same time, the agency must also develop an operating plan for fiscal year 2024 funding provided by an appropriations bill passed March 8 that instructed NASA to spend at least $300 million, and as much as $949.3 million, on MSR in 2024.

The TBD in the fiscal year 2025 budget request for MSR reflects the uncertainty about the plans for carrying out the program, said Lori Glaze, director of NASA’s planetary science division, during a town hall meeting at LPSC March 11. “We’re trying to give the response team the time they need to complete their assessment and provide the recommendation,” she explained.

Once that work is done, NASA will amend its budget request to seek specific funding for MSR in 2025, but at the expense of the allocations requested for other planetary programs in the original proposal. “I do not expect the top level of the planetary budget to go up above the $2.73 billion” in the original request, she said, which is already fully allocated to other programs. “We need to think about how we support Mars Sample Return within a balanced planetary portfolio and within that $2.73 billion top line.”

NASA faces similar challenges for determining MSR funding in 2024 within the limits set by the appropriations bill. “This is going to be the heart of a very difficult process,” she said.

While providing little information about what the new MSR architecture, and its cost and schedule, will be, NASA officials at the conference reemphasized the scientific value of the program.

“Mars Sample Return is one of the highest priorities in the past two decadal surveys. It is an agency priority,” said Lindsay Hays, acting lead scientist for MSR at NASA Headquarters, during a March 12 presentation. The samples, she said, can serve as a “Rosetta Stone” to decode the early history of terrestrial planets.

Those officials acknowledged, though, the uncertainty about MSR was affecting science planning. That includes potential surveys beyond the crater rim by Perseverance to collect samples. “We’re awaiting to see what the MIRT results are,” Hays said. “The MIRT is going to help us understand what is our future architecture and future schedule.”

She added that “maximizing sample number and simple diversity is absolutely key” for the mission, a point Wadhwa also made.

“We are currently awaiting the outcome of the MIRT in terms of what the timeline is going to look like,” Wadhwa said, which will shape what kind of traverse Perseverance will take to collect additional samples at and beyond the crater rim. “We have an amazing set of rocks awaiting us in those regions.”

China's Zhurong Mars rover returns panorama ahead of planetary blackout

China's Mars rover Zhurong has produced a remarkable new panorama of its surroundings in Utopia Planitia to mark 100 days of activity on the Red Planet as preparations continue for the rover to spend more than a month in safe mode this autumn. The six-wheeled, solar-powered rover has covered 3,491 feet (1,064 meters) since rolling onto the Martian surface on May 22. But from mid-September to late October, the rover and its orbiting companion, Tianwen-1, will be in safe mode as the sun's charged particles interfere with their communication with Earth. In preparation for the break, Zhurong paused to take a good look around with its panoramic camera. The returned image shows the rover and its solar arrays and antenna close to a dune, a feature type that mission scientists are keen for Zhurong to analyze. A number of distant features can be seen on the horizon of the panorama including, above Zhurong's antenna, the backshell from the rover's landing in May. Zhurong visited the discarded gear up close in July. Since landing on May 14 and deploying onto the surface a week later, Zhurong has been moving south from its landing platform, analyzing different rocks, dunes and other features as it goes. The Tianwen-1 orbiter with which Zhurong hitched a ride to Mars has been orbiting so that it passes over Zhurong once a day to relay data to mission control in China. The National Astronomical Observatories of China (NAOC) also released an image from Tianwen-1's high resolution camera which shows Zhurong's journey from the lander, including tracks the rover left in the Martian surface.

A panorama of Utopia Planitia returned by the Zhurong rover in late August 2021. (Image credit: CNSA/PEC)

Meanwhile, a new paper on the geological characteristics of Zhurong's landing area identifies a number of features and landforms that scientists working on the mission hope to study as the rover continues south.

A high-resolution image from the Tianwen-1 orbiter showing Zhurong's roving progress through late August 2021.  (Image credit: NAOC)

According to the paper, the rover will investigate transverse aeolian ridges, or dunes, as well as troughs, caused by erosion, and particularly mysterious pitted cones. One of the scientists' key objectives is to use Zhurong's ground penetrating radar to determine the thickness and distribution of Martian soil near some landforms hypothesized to have been created by the presence of subsurface water or ice.

The presence of water would have profound implications for understanding of the climate history of Mars, potential resources for future crewed missions and even as a habitat for simple subsurface life.

The paper also notes that a number of pitted cones are present a number of kilometers to the south of the rover's position. A close-up look at these with Zhurong's terrain camera, multispectral camera, and Mars Surface Composition Detector could help provide fresh insights into how these features were formed, since current hypotheses range from volcanism, mud- or hydrovolcanism, or even underground water flows.

Despite their industry, both Zhurong and Tianwen-1 will soon go into safe mode because of a solar conjunction preventing communications between Earth and Mars. Both spacecraft will pause activities from mid-September through late October, as the sun and the charged particles it releases will obscure our view of Mars from Earth and interfere with radio communications between the two planets. 

A route map showing Zhurong's travels south from its landing platform. (Image credit: BACC)

Both spacecraft will autonomously carry out health assessments, self-monitoring and trouble-shooting until communications can be restored. 

The China National Space Administration and the People's Bank of China also jointly released silver and gold commemorative coins featuring the rover to celebrate Zhurong's 100 days on Mars.

Nanocardboard flyers could serve as martian atmospheric probes

This summer, NASA plans to launch its next Mars rover, Perseverance, which will carry with it the first aircraft to ever fly on another planet, the Mars Helicopter. As the first of its kind, the Mars Helicopter will carry no instruments and collect no data - NASA describes merely flying it all as "high-risk, high-reward" research. With the risks of extraterrestrial flight in mind, Penn Engineers are suggesting a different approach to exploring the skies of other worlds: a fleet of tiny aircraft that each weigh about as much as a fruit fly and have no moving parts. These flyers are plates of "nanocardboard," which levitate when bright light is shone on them. As one side of the plate heats up, the temperature differential gets air circulating through its hollow structure and shooting out of the corrugated channels that give it its name, thrusting it off the ground. A recently published study demonstrates nanocardboard's flying and payload-carrying abilities in an environment similar to that of Mars. The thinner atmosphere there would give the flyers a boost, enabling them to carry payloads ten times as massive as they are. The weaker Martian gravity would further enhance their capabilities. The study, published in the journal Advanced Materials, was led by Igor Bargatin, Class of 1965 Term Assistant Professor in the Department of Mechanical Engineering and Applied Mechanics (MEAM), and John Cortes, then a graduate student in his lab. Fellow lab members, Christopher Stanczak, Mohsen Azadi, Maanav Narula, Samuel M. Nicaise and MEAM Professor and master's program chair Howard Hu also contributed to the study.

"The Mars Helicopter is very exciting, but it's still a single, complicated machine," Bargatin says. "If anything goes wrong, your experiment is over, since there's no way of fixing it. We're proposing an entirely different approach that doesn't put all of your eggs in one basket."

Bargatin's group has been experimenting and improving on their nanocardboard design since 2017. Inspired by the common paper packaging material, they collaborated with researchers at the Singh Center for Nanotechnology to achieve a record-setting ratio of weight and stiffness, as reported in a recent Nature Communications paper.

Like paper cardboard and other "sandwich structured composites" used in architecture and aviation, nanocardboard's material properties stem from corrugation. Consisting of a hollow plate of aluminum oxide walls that are only a few nanometers thick, that corrugation is a regular pattern of channels spanning the plate, which enhance its bending stiffness and prevent cracks from propagating.

These channels are also responsible for the plates' ability to levitate, as creating a temperature differential generates an air current that flows through their hollow structure.

"The air current through these micro-channels is caused by a classical phenomenon called 'thermal creep,'" says Hu, "which is a rarefied gas flow due to the temperature gradient along the channel wall."

Their recent study allowed the researchers to measure the flyers' ability to lift mock payloads - silicone rings, attached to the top of the plates - thanks to a new low-pressure test chamber with integrated cameras and light sources.

Studying these dynamics are important for vetting nanocardboard's potential as a material for atmospheric probes, especially on other worlds, including Mars, Pluto and Neptune's moon Triton. Because Bargatin's nanocardboard flyers weigh about a third of a milligram, it would take more than a million of them to equal the mass of the Mars Helicopter, and more than six billion to equal the ground-based rover that will deploy it.

But even in the ideal environment of the Martian atmosphere, the tiny flyers would still be limited to sensors and payloads that are at most a few milligrams. As such, Bargatin is now collaborating with other researchers on how to miniaturize chemical sensors that could detect water or methane - key signatures of life on Mars.

"In addition to carrying sensors," Bargatin says, "our flyers could simply land and have grains of dust or sand passively stick to them, then transport them back to the rover so it doesn't need to travel as far."

The rover could also provide a means of piloting the nanocardboard flyers. Despite having no moving parts, they can be steered by way of a pinpoint laser, since the direction of the air flowing out of their channels depends on which parts of the plate are heated.

Terrestrial applications are also possible.

"The Earth's mesosphere is pretty similar to the Martian atmosphere in terms of density, and we currently don't have anything that flies there, since it is too low for space satellites but too high for airplanes and balloons," Bargatin says. "Ideally, you'd like to have some sensors up there as well. The more knowledge you have about the movement of the atmosphere at that level, the better predictions you can make about Earth's climate and even weather."

Landing site selected for UK's ExoMars rover in 2021

A group of scientists and engineers in Leicester has recommended Oxia Planum as the best landing site for the British-built Mars rover. Due to land in 2021, the ExoMars rover will be the first of its kind to travel across the Martian surface and drill down to determine if evidence of life is buried underground. Dr. Graham Turnock, Chief Executive of the UK Space Agency said: "After the Earth, Mars is the most habitable planet in the solar system, so it's a perfect destination to explore the possibility of life on other planets, as well as the history of our own." Both of the potential landing sites - Oxia Planum and Mawrth Vallis - preserve a rich record of geological history from the planet's wetter past, approximately four billion years ago, however the potential for science return had to be balanced with the prospect of landing safely. Professor John Bridges, from the Space Research Centre, University of Leicester, a member of the Landing Site Selection Working Group, explains why Oxia Planum has been recommended: "After over 4 years of careful study of HiRISE and more recently CaSSIS images Oxia Planum was chosen because scientists were convinced that its fine grained sediments, deposited during the ancient Noachian epoch, were ideally suited for the exobiology rover. "With an enormous catchment area the sediments will have captured organics from a wide variety of environments over a long period of time, including areas where life may have existed. The fine sediments should also be ideal for the ExoMars drill - it aims to get to 2 metres depth.

"Remote identification with the Mars Express and Mars Reconnaissance Orbiter Infrared spectrometers shows the presence of clays and other minerals giving clues to its aqueous history. A large group of scientists have been working on proposing, characterising and down selecting the sites, all of which had fascinating aspects, but Oxia Planum is the clear winner on both science and engineering constraints."

The UK Space Agency is the second largest European contributor to the ExoMars mission, having invested euro 287 million in the mission and Pounds 14 million on the instruments. This, in addition to successful negotiations with the European Space Agency (ESA), secured key mission contracts for the UK space sector.

Sue Horne, Head of Space Exploration at the UK Space Agency said: "I have been working on ExoMars for over 10 years and am amazed at the ingenuity and dedication of UK engineers and scientists in building the rover and instruments that will work in the extreme environment of Mars. Our end goal is in sight and it is getting very exciting."

The government's modern Industrial Strategy is backing businesses to succeed by increasing investment in science, because countries that invest in ideas create more opportunities for business. The ambition is for the UK be the world's most innovative economy - and the development of the ExoMars rover in the UK is a part of this ambition.

Airbus Defence and Space in Stevenage is leading the build of the rover while the UCL Mullard Space Science Laboratory is leading on a key instrument known as the PanCam, a high-resolution 3D camera which will be used to look at the terrain and rocks to try to detect signs of life. The University of Leicester and Teledyne e2v are working on the Raman Spectrometer with STFC RAL Space providing some of the electronics, including the data processing board.

The recommendation was made following a two-day meeting held at the National Space Centre in Leicester, UK, which saw experts from the Mars science community, industry, and ExoMars project present and discuss the scientific merits of the sites alongside the engineering and technical constraints. The Leicester recommendation will be reviewed internally by ESA and Roscosmos with an official confirmation expected mid-2019.