Issue No. 271

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The Orbital Index

Issue No. 271 | May 29, 2024

🚀 🌍 🛰

Voyager 1 is so back. Last November, Voyager 1, stopped sending usable science and engineering data. After five months of troubleshooting and poking the probe, the venerable mission team determined that the probe’s flight data system (FDS), responsible for packaging data for transmission by the telemetry modulation unit, had what was likely a single corrupted data chip, impacting ~3% of the FDS memory—possibly due to a high-energy particle impact or simply old age. The team embarked on relocating FDS code to avoid the corrupted chip, but Voyager’s 47-year-old hardware had no memory region large enough to hold the entirety of the contents of the failed 256-bit chip (the Voyager probes have just 69,656 bytes of memory each). Engineers decided to split the code up and remove sections of existing code that are no longer needed—one example was the code used for high data rates since the probe’s distance from Earth now limits transmissions to 40 bits/sec. As a first step, the team began reorganizing code used to report engineering data into newly available memory and was able to start receiving good data on the probe's health status last month. Now the team has relocated code responsible for packaging data from the plasma wave subsystem and magnetometer instrument, successfully reviving the science mission of humanity’s most distant object (162.8 AU and moving away at 16.99 km/s)! Two more instruments are still waiting for their FDS functionality to be restored, the cosmic ray subsystem and the low energy charged particle instrument (the probe also has six deactivated or defunct instruments). In case you’re wondering, Voyager 2, although not quite so distant, would like you to know that it was launched first and is a much less needy probe.

One of 8 boards from the Voyager FDS. Credit: NASA/JPL

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Starship’s upcoming fourth flight. SpaceX has announced that the next flight of Starship, now termed “Flight-4”, could happen as soon as June 5th at 8 am ET—pending regulatory approval (here’s Ars’ deep dive). In a detailed report on Flight-3, the company detailed the root causes of its failure and outlined objectives of the upcoming test flight, which will focus on a controlled entry for Starship as well as Super Heavy conducting a successful soft landing burn in the Gulf of Mexico. To reduce the landing mass of the world’s largest booster, the flight will also (probably temporarily) jettison Superheavy’s hot staging ring. (We wonder if a small creature with hairy feet might someday fish the once-glowing ring out of the gulf, unknowingly kicking off an epic adventure to rid Earth of evil.) Starship itself will forgo any on-orbit activities like those conducted during Flight-3, instead focusing solely on maintaining control during entry (and hopefully providing even longer live views of reentry plasma formation), with a ballistic trajectory that will have it again land in the Indian Ocean. Going forward, SpaceX hopes to continue to increase the cadence of Starship launches, following Flight-4 quickly with Flight-5, possibly as soon as a month later (although, as always, this is probably quite optimistic). For reference, Flight-2 came 7 months after Starship’s initial flight on April 20th, 2023; Flight-3 came 4 months later; and, Flight-4 is looking likely to launch less than 3 months after Flight-3. Regulatory approval may be easier for this flight since neither vehicle triggered its flight abort system—this means that if the FAA decides that the public was not endangered in any way, it may go ahead with certification of Flight-4 while Flight-3’s mishap report is still open (this will hold true for future flights as well).

Starship S29 and B11 in the midst of a Wet Dress Rehearsal on May 20th. Credit: SpaceX

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Weird Papers

XKCD #2844

News in brief. Rocket Factory Augsburg started hot firing their Helix engines at SaxaVord Spaceport Starfish Space won a $37.5M Space Force contract to develop their Otter on-orbit servicing vehicle for GEO, targeting 2026 Twelve European countries signed ESA’s Zero Space Debris CharterFirefly might be up for sale Sierra Space delivered Dream Chaser to NASA Kennedy for preparation ahead of its first flight to the ISS sometime late this year, launched on a ULA Vulcan rocket SpaceX completed their first direct-to-cell video call via Starlink and noted that service via T-Mobile will start later this year Starliner is delayed again, this time due to an unresolved helium leak onboard—NASA still hopes to launch it early next month Airbus won a $369M ESA contract to build Vigil, a spacecraft that will provide early warning of severe solar activity (for the next solar cycle) from L5, a vantage point which will allow it to observe activity on part of the Sun’s surface which isn’t yet visible from Earth SpaceX launched the first of many spy satellites for the NRO Commercial imaging startup Sattelogic reduced their workforce by 13% The Dominican Republic might build their own commercial spaceport China’s elusive spaceplane deployed another unknown object into its orbit The first of NASA’s pair of PREFIRE satellites (c.f. Issue 256) successfully launched on a dedicated Electron and established contact with ground systems to start its science mission of measuring how the Earth radiates heat from its poles.

NASA’s first PREFIRE spacecraft launching from its deployer aboard Rocket Lab’s Electron rocket.


ESA released early images from Euclid, including this infrared view of Messier 78. “Euclid’s instruments can detect objects just a few times the mass of Jupiter, and its infrared ‘eyes’ reveal over 300,000 new objects in this field of view alone.” The telescope will start its primary six-year survey mission shortly, studying the distribution of matter in the Universe to help us understand the cosmic web, dark matter, and dark energy.

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