Mars

The Future of Mars Exploration Belongs to Helicopters

NASA's Mars Helicopters: Present, Future, and Proposed: A family portrait of Mars helicopters - Ingenuity, Sample Recovery Helicopter, and a future Mars Science Helicopter concept. Credits: NASA/JPL-Caltech.

Even though there’s no firm date for a Mars sample return mission, the Perseverance rover is busy collecting rock samples and caching them for retrieval. We’ve known of the future Mars sample return mission for a while now, and as time goes on, we’re learning more details.

The latest development concerns helicopters. With Ingenuity’s success, NASA has decided that the sample return mission will take two helicopters.

When NASA’s Perseverance rover landed in Mars’ Jezero crater, it had a passenger secured to its belly: a small rotorcraft named Ingenuity. It was the first powered, controlled extraterrestrial flight by an aircraft. (The first unpowered flight was a Soviet balloon flight on Venus as part of the Vega 1 mission in 1985.)

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Ingenuity met all its goals and more. It was initially intended to perform five flights up to 90 seconds long each in 30 days. It performed well beyond that, with its 33rd flight taking place on September 24th, 2022, over 18 months since the mission landed on Mars.

Ingenuity hanging from the belly of the Perseverance rover during deployment to the Martian surface. Image Credit: By NASA – https://mars.nasa.gov/resources/25778/ingenuity-helicopter-is-ready-to-drop/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=103068384

The eventual Mars sample return mission will be a joint endeavour between NASA and the ESA. The mission is still being developed, and now it looks like the agencies will send not one but two helicopters.

We’ve known about this development for a while. But in a new blog post update, Bob Balaram, Chief Engineer of the Ingenuity Project, explains in more detail the advantages that helicopters bring to exploring Mars. Balaram originated the Ingenuity helicopter and guided it through its first year of operations on Mars.

Balaram compares Ingenuity’s first flight to another first—the Wright Brothers’ famous flight in North Carolina in 1903. “It was very much like another day in December 1903, here on Earth,” Balaram writes. “On Mars, it was our Wright Brothers moment – a short flight – rising a few meters into the sky, hovering briefly in the thin air, making a turn, and descending to land. A simple flight, but one that ushered in aerial mobility for exploring Mars.” The comparison is apt because Ingenuity took a tiny piece of the Wright Flyer aircraft to Mars.

Ingenuity has been on Mars for over 500 sols now when its mission was originally intended to last only 30 days. That type of success would embolden any engineer, and now NASA wants to build on that success. Both future helicopters will be similar to Ingenuity, but there will be some key differences. They won’t be there to test technology; they’ll have duties to perform.

“These Sample Recovery Helicopters, with wheels instead of feet, and a small manipulator arm with a two-fingered gripper, will, if needed, carry precious sample tubes from a sample cache depot back to the Mars ascent vehicle for launch back to Earth,” Balaram wrote.

This artist’s illustration of a Mars Sample Return helicopter highlights the rotorcraft’s wheels and sample-retrieving arm. Image Credit: NASA/JPL-Caltech.

The Mars rovers are extremely impressive machines, from Spirit and Opportunity to MSL Curiosity and Perseverance. Their performance and endurance on Mars are a testament to human capabilities. But helicopters take exploration to the next level.

Balaram talks about the 4R’s of exploration: Reach, Range, Resolution, and Robotics. “Mars helicopters are unique in their ability to reach locations otherwise inaccessible to other forms of mobility. They can fly over terrain that is simply not traversable by a wheeled rover, as shown by Ingenuity’s flight over the treacherous sand dune fields of the Seitah region in Jezero crater.

A rover’s reach is limited, but helicopters can greatly improve the reach of exploration by rovers, and it might be hard to imagine future rover missions to the planet without helicopters as part of the mission design. Helicopters can act as route-finders in advance of giving the rover travel instructions. They can examine areas for sampling desirability. They can hover next to features like crater walls and even explore lava tubes.

Helicopters can open up other regions of Mars for surface exploration, too. Rovers are heavy, and engineers are very cautious about where they land them, cognizant of the so-called Mars Curse. But much-lighter helicopters could land elsewhere. “Because of their low weight, entry capsules carrying a helicopter can be targeted to even the highlands of Mars, with the helicopters flying out the final leg of the entry, descent, and landing journey. For the first time, we can have true global access to the red planet,” Balaram writes.

This image shows the landing locations of NASA’s Mars missions. None have explored the planet’s southern highlands, which have a much thicker crust and are higher in elevation by up to 3 km. The striking difference between the southern highlands and the northern hemisphere is called the Martian Dichotomy. Image Credit: By NASA/JPL-Caltech – https://photojournal.jpl.nasa.gov/jpeg/PIA24320.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=97863997

Ingenuity had a very limited range. As a test vehicle, increasing its range wasn’t a priority. But future Mars helicopters could have a much greater range. “While Ingenuity as a technology demonstration was limited to a flight capability of about 1 km per sol, future larger helicopters could have the endurance to allow 10’s of km per sol traverses,” Balaram writes. “With that kind of capability, large-scale, close-up exploration of a wide area on Mars becomes possible.” Balaram says that helicopters could open Valles Marineris up for exploration. Even the planet’s ice caps could be within reach one day.

Helicopters will improve image resolution, too. The MRO has a powerful camera system that has imaged almost the entire surface of Mars. It’s led to all kinds of discoveries on Mars and has helped choose landing spots for surface missions. But a much cheaper, less sophisticated camera on a helicopter can image specific areas of Mars’ surface with higher resolution than MRO or any other orbiter. And for much cheaper.

Balaram’s fourth R is robotics. Robotic technology is advancing daily, and increased robotics on a Mars helicopter means greater autonomy and mobility. If NASA ever develops a helicopter that can explore lava tubes, for example, robotics will have to be up to the task. The communications delay between Earth and Mars prohibits the type of fine control needed for that type of exploration.

“High-performance processors enabling autonomy, unprecedented mobility through both flying and driving, and a true manipulation capability with a robot hand can enable much more than sample tube retrieval,” Balaram wrote.

As if this isn’t impressive enough, engineers are already developing a more advanced craft for future exploration. “A more capable Mars Science Helicopter with the ability to carry almost 5 kg of science payloads is also in early conceptual and design stages,” wrote Balaram.

In a NASA white paper titled “Mars Science Helicopter: Compelling Science Enabled by an Aerial Platform,” Balaram and 20 other authors explained in detail how a future MSH would work.

The NASA MSH white paper considered two rotorcraft concepts; a coaxial design and a larger hexacopter design. Image Credit: NASA.

The white paper outlines two potential designs for the MSH: a coaxial and a hexacopter. The coaxial is based on Ingenuity, known as the Mars Helicopter Technology Design (MHTD.) The hexacopter is larger, about 30 kg, compared to 4.6 kg for the MHTD. Both have the same approximate range, 10 km laterally and 2 km vertically, but the hexacopter can carry a much larger payload, about 5 kg compared to about 1.3 kg.

The white paper identifies key science objectives that can be uniquely addressed by rotorcraft on Mars.

This image from the white paper shows six science objectives. The coloured dots represent rotorcraft capabilities that address each objective. Green is for range, purple is access to hazardous terrain, and blue is access to the planetary boundary layer. The planetary boundary layer is an atmospheric boundary layer which extends ~5–10 km above the surface. It’s a previously inaccessible region of Mars that controls interactions between the atmosphere and the surface. Image Credit: NASA

The white paper also identifies science payloads and specific locations where the MSH could meet the scientific objectives. These are broken down into three mission concepts, with each one having different instruments. They are Clays and Astrobiology, Ice-Exposing Scarps, and Crustal Magnetism. These three objectives are well-known to Universe Today readers.

The instruments include sampling arms and microdrills, infrared imagers, neutron spectrometers, a meteorology package, a magnetometer, and a magnetometer.

This image from the white paper illustrates one of the mission concepts considered for a future MSH. The goals are to determine the relationship between recent climate change on Mars and the proposed Mars ice ages. It also includes mapping the horizontal and vertical distribution of accessible, near-surface water ice. Image Credit: NASA.

White papers are fascinating because they’re a window into all of the thinking that goes into an eventual mission design. As far as the authors are concerned, helicopters will likely be a mainstay of Mars missions. “The coaxial vehicle is sufficiently low-mass and low-volume that it should be considered in all future launch opportunities to Mars’ surface,” the paper says in its conclusion. “We recommend all possibilities be considered.”

This is an exciting time in Mars exploration. It’s hard to predict the effect rotorcraft will have on future missions. Maybe one day, a Mars mission will contain a stationary home base and multiple rotorcraft.

Maybe in the future, we won’t even send rovers to Mars.