It’s a bit hard to believe, but this issue marks one full year of The Orbital Index. We’ve immensely enjoyed diving down Internet rabbit holes and writing about space each week. And, we’ve even gotten to meet some of you! As we look forward to more weeks of writing and meeting more of you, we thought this would be a good moment to pause and reflect on the ongoing development of the newsletter and its community. It’d be swell if you could take 3 minutes to complete a quick survey about how you read The Orbital Index and what you think should come next. (We’ll also put it at the bottom so you can read the important space stuff first.)
To another 942,000,000 km trip around our star with weekly doses of rockets and space exploration (and not too much radiation),
— Andrew and Ben
Starlink-4 and a dark sky. This week’s Starlink-4 mission launched 60 more Starlink satellites. (If you're counting along from home, you’ll notice this is the 5th dedicated Starlink launch… but, the first launch isn’t counted due to its v0.9 hardware.) This launch was booster B1056's 4th flight and the fastest re-flight of a Falcon 9 to date at 62 days. Unfortunately, the booster, which could have been SpaceX’s 50th recovery, missed the drone ship and “soft-landed” in the ocean nearby—boosters are guided on a ballistic trajectory to the side of the landing area and adjusted onto the landing site at the last second for safety. Starlink promises global low-latency internet service via (initially) pizza box-sized receivers (here’s a super-good latency simulation video), with North America scheduled to receive initial coverage later this year. However, Starlink has turned into a major controversy for SpaceX due to the VLEO orbit of the satellites (550 km for the initial shell—340 & 1,200 km later), their unexpectedly high apparent magnitude, and the longer-term question of whether mega-constellations from SpaceX, OneWeb, Project Kuiper, and others may eventually lead towards Kessler syndrome due to space debris. Some in the astronomy community are vocally against the continued rollout of Starlink due to its impact on both visible- and radio- astronomy (to the point of a potential lawsuit). Others advocate for the socio-economic benefit of internet service availability that isn’t tied to living in proximity to a metropolitan area (illustrative map)—economic success is disproportionately available to those that have high-quality access to the Internet. Comparing these costs and benefits, when those they affect are so different, is a difficult task. What has been lacking so far from the overwrought discourse are clear solutions. One first goal proposed by some American Astronomical Society astronomers is decreasing the brightness of mega-constellations below naked-eye visibility. In response, SpaceX has begun painting satellites to decrease their albedo (and has indicated future reductions as well). Others have suggested increasing orbital height, but that comes with increased latency and difficulty in de-orbiting defunct satellites. Ethan Siegel wrote a piece in Nov. that, while overly dramatic, plots clear steps that could be taken to allay astronomers’ objections. Meanwhile, Dr. Pamela Gay has a well-written critique of astronomers’ single-minded approach to the issue. We feel that regulation of mega-constellations is lacking and that with decreasing launch costs, this problem will only grow. Legal and technical solutions are needed, and until they are cohesively proposed and mandated, little is likely to change.
NASA announced funded concept development of four interplanetary missions. One or two of these Discovery-class missions will be selected next year for continued funding. The missions under consideration include the Io Volcano Observer (pdf), a mission to study volcanic Io through a series of close flybys and learn how tidal forces shape planets; Trident, a flyby mission to study the frost geysers and (possible) icy subsurface oceans of Neptune’s moon Triton; and, two missions to Venus, including a spherical lander probe called DAVINCI+ (pdf) which will look for lost oceans, and VERITAS, an orbital synthetic aperture radar and infrared imager to determine whether Venus has active plate tectonics and volcanism, seeking to answer how a planet so similar to Earth could end up so different. NASA’s Discovery Program typically funds missions that cost less than $300 million, including such past successes as the Kepler space telescope, the Lunar Reconnaissance Orbiter, the Mars Pathfinder and Mars InSight landers, and Dawn, with the upcoming Lucy and Psyche missions to asteroids launching in 2021 and 2022.
- According to a recent study, asteroids orbiting main-sequence stars (like our Sun) will be destroyed as the stars age by their increased luminosity alone. This is due to the YORP effect (which we’ve mentioned a few times in the past), in which heating from sunlight slowly spins up asteroids until they fly apart. “When our sun dies and runs out of fuel in about 6 billion years [...] its luminosity [...] will bombard our asteroid belt with increasingly intense radiation, subjecting the asteroids to the YORP effect and breaking them into smaller and smaller pieces.”
- Hubble has detected the smallest clumps of Dark Matter yet seen by looking at the way it gravitationally lensed quasars moving behind it.
- Here are two paper summaries from Brian Koberlein for Universe Today about the continuing Crisis in Cosmology over the nature of Dark Energy, if it even exists. First is evidence that we’ve been wrong about the reliability of the brightness of Type Ia supernovae, which gives a result for the expansion rate of the Universe without requiring Dark Energy. However, a second method of calculating the Universe’s expansion rate using gravitational lensing still requires Dark Energy to match our observations. Both paper summaries are compelling, and it remains clear that there’s something odd going on in the Universe that we definitely don’t yet understand.
- Recordings of geoneutrinos—neutrinos coming from within the Earth—by the Borexino detector at the world's largest underground laboratory indicate that radioactive decay is a significant source of the Earth’s internal heat, driving processes like volcanoes and the Earth’s magnetic field.
- Results from New Horizons’s flyby of Arrokoth (née Ultima Thule) in the Kuiper Belt suggest that the snowman’s lobes orbited each other and drifted together slowly, supporting a model of planetesimal formation where bodies form slowly by the gravity-driven collapse of clouds of solid particles (paper), rather than rapidly by high-speed collisions, as the competing theory of hierarchical accretion suggests.
- Using data from the last 150 years, it appears that destructive solar superstorms occur every 25 years or so (paper). Carrington Event-level storms may happen with little warning and be more common than thought. No further research is needed.
- Christina Koch is reunited with her pup after 328 days apart (in space).
- NASA is crowdsourcing solutions for mechanical Venus rovers (with a $15,000 prize to the best entry), and Scott Manley has a video about past proposals for mechanical computers and sailing rovers to explore the hot planet, such as AREE.
- Quindar Tones are those characteristic beeps you hear in every old space audio recording.
- The ESA is developing a pair of rovers to explore the Moon’s surface.
- An in-depth NYT piece about how the United Arab Emirates’ Hope orbiter was developed in collaboration with U.A.E. researchers (many of whom are women under 35) and US universities—it launches for Mars this summer.
- Breakthrough Listen has released a 2 petabyte optical and radiofrequency dataset from large telescopes around the world—dig in and see what you can find! Meanwhile, the SETI Institute and the Very Large Array in New Mexico (see the movie Contact) are teaming up to search the VLA’s existing data stream for technosignatures.
- Casey Handmer takes a detailed look at why Starship shouldn’t be staged, and it all comes down to payload efficiency. “While the Saturn V delivered about 4.5% of its launch mass to orbit, the Electron delivers [...] only 1%”.
- Only part of betelgeuses is dimming.
- A look at a few of the lasting ‘mysteries’ of the Spitzer Space Telescope mission.
- Lest you think Spinlaunch is the only crazy in town, Amazon has patented a mechanism for throwing satellites into space with a multi-drone-guided whip… on a boat. Note, though, that Amazon (and other tech companies) have a history of patenting things that they’ll never actually build, such as Amazon’s underwater fulfillment centers.