¶Does Clipper have a MOSFET problem? NASA’s Europa Clipper mission recently came under scrutiny at the Agency due to reports of its MOSFETs failing under lower-than-expected radiation levels (at least according to a “non-NASA” customer using the same MOSFETs). The intense radiation in Jupiter’s radiation belts, especially from heavy ions expelled by Ionian volcanism and then trapped and accelerated by Jupiter’s magnetic field, 20,000x stronger than Earth’s, can cause Single Event Effects (SEEs), including Single Event Upsets (SEUs, aka bit flips) and Single Event Latch Ups (SELs) in MOSFETs. The total ionizing dose of radiation also builds up over time, causing transistors to accumulate charges at their silicon-oxide boundaries, increasing leakage current, and creating interface traps—these effects alter the voltage needed to turn the MOSFET on or off, disrupt the flow of electrons, and lead to increased energy use and overheating. Anticipating Jupiter’s environment, Clipper’s primary electronics are housed in a 9.2 mm aluminum-zinc alloy radiation vault, but some electronics must still operate outside the vault. In addition to the vault, common radiation mitigation techniques such as error-correcting codes (ECC) and triple modular redundancy (TMR) are also used by the mission to manage SEUs and hardware degradation. Testing by a NASA “tiger team” of the MOSFETs in question (from Infineon Technologies, who say they have “stringent processes in place to ensure compliance with all relevant quality and performance standards for our products.”) is happening in parallel with final preparations for launch in October—the outcome of this testing will likely determine whether the ~$5B craft is launched or delayed for some amount of rework. If needed, potential solutions include replacing Clipper’s faulty chips with more robust versions or adjusting the spacecraft’s trajectory to minimize radiation exposure (although the latter could reduce the amount of Europa that is covered by flybys). Perhaps oddly, the very same harsh Jovian radiation that threatens Clipper is thought to be a potential driver of life on Europa, oxidizing the upper layers of its subsurface ocean to produce energetic molecules, which may become the building blocks of microbial life deeper down. |
|
 | A scanning electron microscope view of MOSFET damage after exposure to Ta ion irradiation. |
|
The Orbital Index is made possible through generous sponsorship by:
  |
|
¶Papers- An icy exoplanet in its star’s habitable zone (where liquid water could occur) may also have a nitrogen-rich atmosphere, according to tentative JWST data (paper). LHS 1140 b, located ‘only’ 48 light-years away, orbits a low-mass red dwarf star and maybe a tidally-locked super-Earth composed of 10-20% water by mass. Picture a frozen world with a possible liquid ocean like a bullseye on the side always facing its star. Confirmation of the atmosphere will require additional observation.
- A distant, gigantic, ring-shaped structure 1.3 billion light years in diameter may challenge our understanding of the Universe as smooth and isotropic. The odds of its significance as an outlier (as opposed to statistical noise) appear to be 4.5 sigma. “This is the seventh large structure discovered in the universe that contradicts the idea that the cosmos is smooth on the largest scales. If these structures are real, then it's definitely food for thought for cosmologists and the accepted thinking on how the universe has evolved over time.” The researcher responsible for the find, Alexia Lopez, also discovered (5-sigma) an arc-shaped structure 3.3 billion light years across, an appreciable percentage of the observable Universe’s 94 billion light years width. (See also the Sloan Great Wall and the Hercules-Corona Borealis Great Wall, which is 1/10th the size of the visible Universe.)
- Closer to home, Gaia stellar motion data reveals that the Radcliffe Wave, a 9,000-light-year-long wave-shaped chain of gas in our galactic neighborhood, is also moving in a wave-like way (paper). Due to the Milky Way’s gravitation, it oscillates around the midplane of the Milky Way much like a stadium wave and "appears to form the backbone of the nearest spiral arm in the Milky Way," possibly implying that spiral arms of galaxies oscillate in general. 🌊
- In other potentially-paradigm-shifting news, galactic rotation curves seem to remain flat over distances that call into question our theories of dark matter. Under normal assumptions of gravity, stars orbiting further out in the gravity well of a galaxy would orbit more slowly than those near the center, but this isn’t what we observe, a fact that is used as supporting evidence for dark matter’s existence—a dark matter halo is assumed to exist around galaxies, altering their mass distribution and explaining the observed flat rotation curves. However, those curves should still fall off somewhere for objects outside their dark matter halos, and new observations have failed to find that point even over millions of light years (paper). If this observation holds up, it could support modified gravity theories like MOND as alternatives to dark matter. (Although MOND still has other predictive challenges to overcome as well, with dark matter remaining well supported by observations.)
|
|
 | “To detect dark matter, we just need to build a bird feeder that spins two squirrels around the rim in opposite directions at relativistic speeds and collides them together.” XKCD #2186 |
|
¶Falcon finally has a mishap. With 364+ flights of Falcon-family boosters and just 4 failures, Falcon 9 has been the most reliable and active rocket ever built. Despite all this success however, this week, SpaceX had a Starlink launch fail during an upper-stage relight, deploying 20 Starlink satellites into a 135 km orbit, 150 km lower than planned. The Falcon upper stage developed a visible liquid oxygen leak which caused an engine anomaly when relit. The upper stage was not destroyed, however, and was able to perform Starlink deployment and passivation but was unable to circularize the mission’s orbit. Deployed Starlink satellites were losing ~5 km of altitude per orbit due to atmospheric drag. Despite firing their electric propulsion at maximum thrust, it is assumed they will not be able to raise their orbit quickly enough and will re-enter and burn up in the near future. With two crewed launches in the near future, in addition to the potential launch of Europa Clipper (see above) in October, all Falcon launches are currently grounded pending an FAA mishap investigation. Once a root cause has been identified, SpaceX can likely resume flight and rebuild its track record of reliability quickly due to its current cadence of launching every 2.7 days over the first half of the year—the company has requested an early return to flight while the investigation proceeds based on the results of a ‘public safety determination’ from the FAA, much like it has previously requested of Starship launches. |
|
 | Liquid oxygen ice building up on the Falcon upper-stage MVac engine prior to the anomaly. |
|
| ¶News in brief. Dawn Aerospace received approval from New Zealand to fly their rocket-powered suborbital spaceplane at hypersonic speeds, up to a 24,400 m altitude ceiling ● Chinese commercial launch provider iSpace suffered another launch failure with their Hyperbola-1 rocket due to an anomaly in the fourth stage ● SpaceX moved the next Super Heavy booster to the launchpad in preparation for Starship’s fifth flight ● Skyroot Aerospace successfully completed a proof pressure test of the first stage of their Vikram-1 rocket ● Virgin Galactic completed a new manufacturing facility in Arizona for final assembly of their suborbital Delta vehicles that will launch from New Mexico ● A four-person NASA volunteer crew exited a simulated Mars habitat after spending 378 days in isolation ● X-Bow Systems, a solid rocket motor startup from Albuquerque, secured a $70M Series B to expand production and build a new manufacturing facility in Texas ● Italian space logistics startup D-Orbit launched a US arm of the company which will seek to transform their orbital transfer vehicle into a satellite bus with help from Apollo Fusion founder Mike Casidy ● NASA astronaut Joe Engle, who piloted both the X-15 and space shuttle, passed away at 91 years old ● Poland’s Łukasiewicz Institute of Aviation launched their ILR-33 AMBER 2K rocket, powered by 98% hydrogen peroxide, to 101 km above Earth, the first Polish rocket to reach space. |
|
 | Poland’s Łukasiewicz Institute of Aviation’s ILR-33 AMBER 2K rocket launching from Andøya Space Centre in Norway. |
|
Support Us› Orbital Index is made possible by readers like you. If you appreciate our writing, please support us with a monthly membership! |
|
¶Etc.- The NY Times ‘How Elon Musk and SpaceX Plan to Colonize Mars’ claims that Musk has “directed SpaceX employees to drill into the design and details of a Martian city,” including one team who is “drawing up plans for small dome habitats, including the materials that could be used to build them” while another is looking at Martian space suits and a “medical team is researching whether humans can have children there.” This isn’t surprising for a company designed specifically to go to Mars, but historically there has been little evidence of actual work at SpaceX looking at how anyone would survive on Mars once they got there. They note that “Mr. Musk has volunteered his sperm to help seed a colony.”
- Feds who forced Ukrainian investor Max Polyakov to sell Firefly backtrack years later. "The US government quite happily allowed Polyakov to pump $200 million into Firefly only to decide he was a potential spy just as the company's first rocket was ready to launch," Ashlee Vance wrote. "I've always found the timing of that suspicious and the reasoning behind the accusations against Polyakov flimsy. I obtained every document that I could get my hands on, and the most damaging claim the US could hit Polyakov with was that he hailed from Ukraine, which is near Russia, and that Russia is an enemy of the US in space." (Vance’s book When the Heavens Went on Sale is an interesting and fun read.)
- Some more interesting links: Monitoring marine litter from space is now a reality; Robert Zubrin’s approach to Mars Sample Return; support for the Moon having an iron core, like Earth (paper); and, a Science article on small, nimble weather satellites.
- Russia wants to put 2,600 satellites in orbit by 2036 (with most coming from the proposed Starlink-esque Sfera constellation) despite currently only building about 15 a year.
- If you’re not following ConkSat on LinkedIn, you’re missing out. (A few favorites: the ConkCycle™ high-performance tripropellant nuclear expander rocket and FRAGSAT, the first spacecraft dedicated to increasing the amount of space junk in LEO… it’s more than a satellite… it’s 70 billion steel ball bearings packed into a payload fairing and doesn’t even attempt to create an artificial ionosphere.) 😂
|
|
The Goldstone Solar System Radar imaged the 150-meter-wide tumbling asteroid 2024 MK shortly after it approached within 295,000 km of Earth on June 29th. Goldstone used their 70-meter dish to transmit radio waves and a “smaller” 34-meter antenna to receive the reflected signal. This bistatic mode enabled imaging of details down to about 10 meters wide on the asteroid’s surface. Planetary radar still blows our minds. Credit: NASA/JPL-Caltech |  |
|
|
