Issue No. 179

The Orbital Index

Issue No. 179 | Aug 3, 2022

🚀 🌍 🛰

Mars Sample Return will include two helicopters. NASA, in an ambitious move that is likely to be widely popular, replaced the ESA-led Mars Sample Fetch Rover from the joint Mars Sample Return (MSR) mission with not one, but two, Sample Recovery Helicopters (SRHs). Despite this design swap, the first option for sample delivery is still Perseverance itself—a rover-to-lander handoff is by far the least complicated method of retrieving the sample tubes that Percy has been filling. The now-complete design review that led to the mission changes relied on recent data about Perseverance's expected lifespan and Ingenuity’s performance. However, if Percy can’t return some or all of the samples, or some science objectives make it unappealing to drive the rover to the MSR landing site, then the two SRHs will be called into action. Each of the 43 sample tubes weighs in at 57 grams, plus its contents, and mission success requires at least 20 tubes to be retrieved, so the helicopters could be busy ferrying sample tubes back and forth across Jezero Crater for quite a while. MSR—first envisioned for launch in 2003 & 2005—is now scheduled to launch the Earth Return Orbiter and Sample Retrieval Lander in Fall 2027 and Summer 2028, respectively. The new plan removes ESA’s rover from the mission, significantly simplifying it overall and sidestepping ESA’s lack of Mars surface heritage. ESA will still build the lander’s Sample Transfer Arm and the solar-electric Earth Return Orbiter. If everything goes as planned, samples will make it to Earth 11 years from now in 2033—China is gunning to get samples first, though, in 2031 (cf. Issue No. 175), so the race is on.

The many components of NASA and ESA’s Mars Sample Return campaign (although we believe the Earth Return Orbiter’s altitude may not be drawn to scale 😉).

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Wentian’s Long March 5B falls on Borneo. China’s Long March 5, which in its CZ-5B station-module-delivery configuration acts like a single-stage-to-orbit vehicle assisted by very beefy liquid-fueled strap-on boosters, burned up spectacularly (below) and scattered debris over Borneo (video) and the Sulu Sea. The almost 22-ton booster is the core stage of the third most powerful active heavy-lift rocket (after Falcon Heavy and Delta IV Heavy) and includes no ability to conduct a controlled reentry. Chinese authorities minimized the fact that the massive booster continues to pose a huge risk of loss of life and damage if it re-enters over the wrong part of the globe (recent paper). CZ-5B’s core stage is far from inconsequential, however—it is larger than the Salyut or Tiangong space stations (although Salyut-7 ended up deorbiting with a spacecraft attached, making it 39 tons altogether) and is now, for the third time, the 4th largest spacecraft to ever re-enter the atmosphere in an uncontrolled manner (list of uncontrolled re-entries, h/t Jonathan McDowell). Debris fell on the island of Borneo on both sides of the Indonesian/Malaysian border. Also things falling uncontrolled from space, albeit significantly smaller: parts of Crew-1 Dragon’s trunk section survived re-entry and fell to Earth in rural Australia.

Starlink Gen 2 makes progress on being shady. SpaceX released details on brightness mitigation techniques developed for its second-generation Starlink satellites as the company continues to push the state of the art in low-albedo satellites (summary thread). Improvements include a maneuver to be performed whenever Gen 2 satellites cross the day/night terminator to avoid reflections from their solar panels, low-reflectivity black paint on most non-flat surfaces that is 5x better than the current best space-stable option, improved materials and coatings for solar panel inter-cell material  (darker and less reflective) and backsheets (light-colored for thermal management, but opaque to avoid sunlight shining through), and a new dielectric mirror film made out of hundreds of layers of PET/PMMA to create a Bragg mirror (and coated in titanium dioxide and silicon dioxide to protect it from the environment of space). This film performs 10x better than their first generation dielectric film, directing light into space via specular reflection instead of diffusely towards Earth. SpaceX will offer the film at-cost to other satellite operators to help reduce the impact of satellites on astronomy industry-wide. Interestingly, the sun shades that were installed on v1.x satellites have been removed from v1.5 sats because they both increased drag and interfered with laser crosslinks. Related: In a positive for space debris, Gen 2 satellites will have a larger surface area to weight ratio, decreasing their time to reentry upon failure or end-of-life.

SpaceX’s new Gen2 dielectric mirror film performance (blue) compared with visors, previous generation film, and super dark paint.

News in brief. In a completely unsurprising move, Russia backpedaled on a 2024 ISS withdrawal—apparently, the critical word in the original statement was “after,” not “in” 2024Eutelsat and OneWeb are officially merging to compete with StarlinkPredominately state-owned Chinese company CAS Space successfully launched their Lijian-1 solid-fueled launch vehicle for the first time and delivered six smallsats to LEO—it is now the largest operational Chinese solid launcherMasten is filing for Chapter 11 bankruptcy (which does not mean that the company will be shut down, only reorganized and downsized, but certainly calls into question their NASA CLPS contract)CAPSTONE completed its third maneuver burn on its ponderous-but-efficient way to the MoonSouth Korea’s Danuri (KPLO) lunar orbiter—which includes NASA’s impressive ShadowCam instrument to peer inside shadowed craters— is targeting an August 5th launch on a Falcon 9Mattel is producing a line of SpaceX-inspired toysUS company X-Bow Systems launched Bolt, their own solid-fueled suborbital rocket.

X-Bow System’s retrofuturistic Bolt.

Judy Schmidt reprocessed a recent image of the M74 (NGC 628) galaxy taken by JWST’s MIRI imager to bring out the details of dust clouds and generated this stunning shot. My God, it's full of stars.

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