Issue No. 248

The Orbital Index

Issue No. 248 | Dec 13, 2023

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That State of Fuel Transfer. SpaceX’s next Starship launch, assuming it reaches orbit, may attempt a 10-ton internal fuel transfer of cryogenic liquid oxygen as part of their NASA tipping point award from 2020. Cryogenic propellant storage and fuel transfer is a key technology for the HLS variant of Starship to be able to access cislunar space. While Musk has tended to brush off the potential difficulty of fuel transfer, this area of space technology is underdeveloped—in part due to the historic lack of any pressing need for such technology. Cryogenic propellant storage is challenging due to the low boiling points of liquid methane (-162 °C), oxygen (-183 °C), and especially hydrogen (-253 °C). Hydrogen, in particular, requires active cooling to avoid boil-off during storage. Meanwhile, RP-1 and other options (water, peroxide, hydrazine, etc.) tend to freeze in space environments (ex., -60° C for RP-1), requiring active heating for long-duration storage. (The need to heat other fuels is one of many reasons long-duration/multi-restart upper stages use hydrogen, and also why SpaceX modified the paint scheme on some Falcon upper stages to increase temperatures during missions with long coast phases.) Starship, with a nominal 6-bar tank pressure, will employ active cooling, a sun shade, or another method to keep fuel temperatures in the range of -182 °C to -170 °C where both methane and oxygen are liquid. Past work on cryogenic fluid management (CFM) includes NASA’s Robotic Refueling Mission program, hosted on the ISS. RRM1 & RRM2 successfully tested liquid ethanol management and coolant replenishment, while RRM3 had to vent its liquid methane prior to completing fluid transfer tests due to a failed cryocooler that was providing cooling for zero-boil-off (ZBO) fuel storage. In addition to Starship’s potential internal transfer test, NASA’s other upcoming cryogenic-fuel-related 2020 Tipping Point mission is LOXSAT, which is being developed by Eta Space as they also work toward their own orbital propellant depot—ULA and Lockheed have been quiet on their own CFM-related Tipping Point awards. LOXSAT will demonstrate many of the technologies needed for CFM, including active and passive thermal management, ZBO storage, quick disconnects, and testing of autogenous vs. helium tank pressurization. LOXSAT will launch NET July 2024 on Electron and is built on top of a Rocket Lab Photon bus with a 9-month mission duration. We’re keen to see both of these CFM demonstrations launch as they will be pushing technical boundaries that need to advance for the next era of cislunar (and eventually Martian) exploration to become feasible.

The Robotic Refueling Mission payload, while attached to the Dextre robotic platform during its time at the ISS. Credit: NASA Goddard

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Short Papers

“The Late Heavy Bombardment was followed a few billion years later by the Comparatively Light but Oddly Specific Bombardment.” XKCD #2845

News in brief. Chandrayaan-3’s propulsion module quietly returned to an ultra-high Earth orbit as ISRO experiments with the future technologies for a lunar sample return mission The first Vulcan launch, with Astrobotics’s CLPS lander onboard, has slipped into early 2024 due to ground systems issues—with SLIM’s landing in mid-Jan and Intuitive Machines targeting a launch on January 12th, the race for a first commercial lunar landing is very much on Satellite imagery startup iQPS went public on the Japanese market at 3.4B yen ($23.7M) Ingenuity took off on its 67th flight and flew 393 m for 2+ minutes NorthStar Earth & Space raised a $14.7M Series D to support the deployment of the first four satellites in their space situational awareness constellation Iran launched a 500 kg biocapsule (possibly containing unknown animals) to 130 km aboard its domestically-produced Salman rocket Egypt joined China and Russia’s International Lunar Research Station (ILRS) Momentus is unable to confirm the deployment of three satellites from the Transporter-9 mission—an as-of-yet-unidentified third-party deployer was used on this mission as the satellites didn’t need propulsion SpaceX launched for the 90th time this year Landspace’s methane-fueled Zhuque-2 rocket took satellites to SSO on its third launch, a milestone for the company—the company is also working on a 200-ton-thrust full-flow staged-combustion methalox engine and the stainless-steel Zhuque-3 which will be able to carry 18 tons to LEO with a reusable first stage Hubble’s gyro issues have been resolved Helicity Space raised a $5M Seed for very early-stage fusion engine development China launched two satellites with the commercial CERES-1 Y9 rocket and sea-launched an internet technology satellite Psyche took its first picture of a distant star field and was able to detect a coronal mass ejection due to being a very “magnetically quiet” spacecraft.

A mosaic made from “first light” images acquired by the twin cameras aboard Psyche. The stars shown are from the Pisces region of the sky, where the cameras happened to be pointed for this first functional imaging test. 

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An image of Mars’s horizon taken by NASA’s 2001 Mars Odyssey orbiter’s THEMIS camera at about 400 km above the Martian surface, roughly the ISS’s altitude above Earth. Normally the infrared THEMIS points directly down, but scientists wanted it to map atmospheric water-ice clouds and dust, so they had to rotate the full spacecraft 90 degrees while ensuring PV Sun exposure and thermal safety, an operation that took three months to plan. They also caught images of Phobos.

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