Elizabeth Rayne reports via Ars Technica: Led by planetary researcher Lonneke Roelofs of Utrecht University in the Netherlands, a team of scientists has found that the sublimation of CO2 ice could have shaped Martian gullies, which might mean the most recent occurrence of liquid water on Mars may have been further back in time than previously thought. That could also mean the window during which life could have emerged and thrived on Mars was possibly smaller. "Sublimation of CO2 ice, under Martian atmospheric conditions, can fluidize sediment and creates morphologies similar to those observed on Mars," Roelofs and her colleagues said in a study recently published in Communications Earth & Environment. [...] To recreate a part of the red planet's landscape in a lab, Roelofs built a flume in a special environmental chamber that simulated the atmospheric pressure of Mars. It was steep enough for material to move downward and cold enough for CO2 ice to remain stable. But the team also added warmer adjacent slopes to provide heat for sublimation, which would drive movement of debris. They experimented with both scenarios that might happen on Mars: heat coming from beneath the CO2 ice and warm material being poured on top of it. Both produced the kinds of flows that had been hypothesized. For further evidence that flows driven by sublimation would happen under certain conditions, two further experiments were conducted, one under Earth-like pressures and one without CO2 ice. No flows were produced by either. "For the first time, these experiments provide direct evidence that CO2 sublimation can fluidize, and sustain, granular flows under Martian atmospheric conditions," the researchers said in the study. Because this experiment showed that gullies and systems like them can be shaped by sublimation and not just liquid water, it raises questions about how long Mars had a sufficient supply of liquid water on the surface for any organisms (if they existed at all) to survive. Its period of habitability might have been shorter than it was once thought to be. Does this mean nothing ever lived on Mars? Not necessarily, but Roelofs' findings could influence how we see planetary habitability in the future.

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SonicSpike shares a report: The quest to return rock materials from Mars to Earth to see if they contain traces of past life is going to go through a major overhaul. The US space agency says the current mission design can't return the samples before 2040 on the existing funds and the more realistic $11bn needed to make it happen is not sustainable. Nasa is going to canvas for cheaper, faster "out of the box" ideas. It hopes to have a solution on the drawing board later in the year. Returning rock samples from Mars is regarded as the single most important priority in planetary exploration, and has been for decades. Just as the Moon rocks brought home by Apollo astronauts revolutionised our understanding of early Solar System history, so materials from the Red Planet are likely to recast our thinking on the possibilities for life beyond Earth.

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Two months ago the team behind NASA's Ingenuity Helicopter released a video reflecting on its historic explorations of Mars, flying 10.5 miles (17.0 kilometers) in 72 different flights over three years. It was the team's way of saying goodbye, according to NASA's video. And this week, LiveScience reports, Ingenuity answered back: On April 16, Ingenuity beamed back its final signal to Earth, which included the remaining data it had stored in its memory bank and information about its final flight. Ingenuity mission scientists gathered in a control room at NASA's Jet Propulsion Laboratory (JPL) in California to celebrate and analyze the helicopter's final message, which was received via NASA's Deep Space Network, made up of ground stations located across the globe. In addition to the remaining data files, Ingenuity sent the team a goodbye message including the names of all the people who worked on the mission. This special message had been sent to Perseverance the day before and relayed to Ingenuity to send home. The helicopter, which still has power, will now spend the rest of its days collecting data from its final landing spot in Valinor Hills, named after a location in J.R.R. Tolkien's "The Lord of the Rings" books. The chopper will wake up daily to test its equipment, collect a temperature reading and take a single photo of its surroundings. It will continue to do this until it loses power or fills up its remaining memory space, which could take 20 years. Such a long-term dataset could not only benefit future designs for Martian vehicles but also "provide a long-term perspective on Martian weather patterns and dust movement," researchers wrote in the statement. However, the data will be kept on board the helicopter and not beamed back to Earth, so it must be retrieved by future Martian vehicles or astronauts. "Whenever humanity revisits Valinor Hills — either with a rover, a new aircraft, or future astronauts — Ingenuity will be waiting with her last gift of data," Teddy Tzanetos, an Ingenuity scientist at JPL, said in the statement. Thursday NASA's Jet Propulsion Laboratory released another new video tracing the entire route of Ingenuity's expedition over the surface of Mars. "Ingenuity's success could pave the way for more extensive aerial exploration of Mars down the road," adds Spacae.com: Mission team members are already working on designs for larger, more capable rotorcraft that could collect a variety of science data on the Red Planet, for example. And Mars isn't the only drone target: In 2028, NASA plans to launch Dragonfly, a $3.3 billion mission to Saturn's huge moon Titan, which hosts lakes, seas and rivers of liquid hydrocarbons on its frigid surface. The 1,000-pound (450 kg) Dragonfly will hop from spot to spot on Titan, characterizing the moon's various environments and assessing its habitability.

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Last week, NASA announced it is working with a technology development company on a new propulsion system that could transport humans to Mars in only two months -- down from the current nine month journey required to reach the Red Planet. Gizmodo reports: NASA's Innovative Advanced Concepts (NIAC) program recently selected six promising projects for additional funding and development, allowing them to graduate to the second stage of development. The new "science fiction-like concepts," as described by John Nelson, NIAC program executive at NASA, include a lunar railway system and fluid-based telescopes, as well as a pulsed plasma rocket. The potentially groundbreaking propulsion system is being developed by Arizona-based Howe Industries. To reach high velocities within a shorter period of time, the pulsed plasma rocket would use nuclear fission -- the release of energy from atoms splitting apart -- to generate packets of plasma for thrust. It would essentially produce a controlled jet of plasma to help propel the rocket through space. Using the new propulsion system, and in terms of thrust, the rocket could potentially generate up to 22,481 pounds of force (100,000 Newtons) with a specific impulse (Isp) of 5,000 seconds, for remarkably high fuel efficiency. [...] The pulsed plasma rocket would also be capable of carrying much heavier spacecraft, which can be then equipped with shielding against galactic cosmic rays for the crew on board. Phase 2 of NIAC is focused on assessing the neutronics of the system (how the motion of the spacecraft interacts with the plasma), designing the spacecraft, power system, and necessary subsystems, analyzing the magnetic nozzle capabilities, and determining trajectories and benefits of the pulsed plasma rocket, according to NASA.

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