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The Orbital Index

Issue No. 274 | Jun 19, 2024

🚀 🌍 🛰

Cohesion on the Moon. The iconic photo of Buzz Aldrin’s boot print on the moon (below) came about because of a little-known, but deliberate, experiment—one to help characterize the physical properties, including the extremely high cohesion factor, of lunar regolith (Apollo 11 soil mechanics test report). While we’ve documented many additional characteristics of regolith since (see, for example, the NASA Engineering Guide to Lunar Geotechnical Properties), we don’t completely understand why it exhibits such high cohesion, especially in low lunar gravity. Hypotheses for this high cohesion include effects from the extremely jagged edges of individual particles, particle-particle Van der Waals force, or the Moon’s unique electrostatic environment (pdf). Understanding the Moon’s surface environment and the effects of its abrasive and cohesive regolith are important both for future lunar robotic missions (regolith mining, lunar radio telescopes) and for humans to learn how to live and work on the Moon safely. Regolith samples, low-g experiments, and simulations all help better our understanding of lunar surface characteristics. An example of this from just two weeks ago: The Swedish Negative Ions at the Lunar Surface (NILS) payload detected negatively charged ions on the far side surface, formed as secondary particles from solar wind particles colliding with the surface. NILS is ESA’s first lunar surface instrument, hosted aboard Chang’e 6. The Moon’s surface charge changes between the light and dark sides, with the light side generally being positively charged while the dark side is negatively charged. Negative ions can even cause regolith dust to levitate a meter or more above the surface and could be one force contributing to regolith cohesion. This phenomenon has also led to the suggestion of maglev-like lightweight lunar rovers that could feature room-temperature molten salt ion thrusters. 🌖🚄

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KASA officially hangs out its shingle. South Korea launched the Korea Aerospace Administration (KASA) at the end of last month. President Yoon Suk Yeol said that the country’s new space agency is targeting a lunar lander in 2032 and a Mars landing by 2045, with plans to spend $72B between now and then. South Korea reached orbit last year with its domestically produced Nuri rocket, and its lunar orbiter Danuri (KPLO) is mapping the Moon’s geology and natural resources (as well as hosting NASA’s ShadowCam). On KASA’s menu for near-term future missions are a second KPLO-style lunar orbiter and an L4-positioned solar activity observation satellite (as well as a 3.5-meter space telescope that could launch in the late 2030s).

Nuri launching in October 2021. Credit: KASA

Short Papers

Fire is actually a potential biosignature, since it means something is filling the atmosphere with an unstable gas like oxygen. If we find a planet covered in flames, it might be an indicator that it supports life. Or used to, anyway, before the fire.XKCD #2202

News in brief. NASA continues to delay Starliner’s return, officially not because of the helium leaks (there is enough propellant for 70 hours and they only need 7 to return to Earth), but because of the desire to conduct additional testing to evaluate the performance of the spacecraft for future missions that will stay docked at the ISS for longer The DoD selected SpaceX, ULA, and (for the first time) Blue Origin to compete for national security launches South Korean startup Nora Space completed a $14.5M Series B to accelerate the development of their methane-monitoring satellite Armenia became the 43rd nation to sign the Artemis Accords Apex raised a $95M Series B to accelerate production of their Aries satellite bus The FAA will not investigate the fourth Starship launch after determining that all flight events occurred within the scope of planned and authorized activities NASA accidentally broadcasted an emergency training scenario on the ISS’s live feed, concerning space watchers that a crewmember was unwell, until later clarifying that all crewmembers were healthy and safe They also postponed an ISS spacewalk due to a ‘suit discomfort’ issue Vast signed a deal with The Exploration Company to use their Nyx space vehicle to supply cargo for Vast’s Haven space station Scout Space selected ABL Space Systems to launch their “Owlet-01” telescope, contingent on the success of ABL’s forthcoming second launch attempt of their RS1 small-satellite launcher NASA selected three concept proposals for their DYNAMIC mission that plans to investigate space weather in the upper atmosphere (80 - 200 km altitude) French startup OsmosX raised €2M+ to continue development of their multi-use space tug that that claim will use a variable thrust, high-ISP propulsion system (~200,000 seconds) that has been in development for 30+ years SpaceX launch computers aborted a Falcon 9 launch at the moment of engine ignition for unannounced reasons (a rare scrub that hasn’t occurred on a Falcon 9 since 2020) SpaceX sent two men and a truck to retrieve several pieces of likely Crew Dragon debris from Saskatchewan Stoke Space successfully completed the first hotfire test of the methane-fueled, full-flow staged-combustion first stage engine of their in-development, fully-reusable Nova rocket planned for launch in 2026.

Stoke Space’s full-flow staged-combustion engine during its successful first hot fire test. The engine can produce >45 tons of thrust.

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Astroascale’s ADRAS-J captured this image of the abandoned upper stage of a Japanese H-2A from ~50 meters.