Issue No. 115

The Orbital Index

Issue No. 115 | May 5, 2021

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¶The passing of Michael Collins. Michael Collins, Command and Service Module (CSM) pilot for Apollo 11, has passed away at age 90. Michael remained in orbit as Neil Armstrong and Buzz Aldrin landed on the Moon. He is often cited (along with subsequent CSM pilots) as the loneliest man in history: as he orbited the lunar surface, he ventured as far as 3,585 km away from the next closest humans, on the other side of the Moon (although xkcd suggests that some Polynesian or Antarctic explorers may have matched this). Previously, as part of Gemini 10, Collins was the fourth human to conduct a spacewalk. After Apollo 11 and leaving NASA, Collins became director and oversaw the construction and opening of the Smithsonian National Air and Space Museum. He later took up painting, wrote Carrying the Fire, which is often considered to be the best astronaut autobiography, and always dreamed of Mars, which he spoke about in an interview with Smithsonian Magazine in 2019. NASA has a remembrance.

Michael Collins took this photo as Neil Armstrong and Buzz Aldrin, ascending from the Moon, rejoined him in lunar orbit. The photo was re-processed by Toby Ord for his Earth Restored collection. Toby’s caption: Collins, who remained in orbit on the Command Module, is behind the lens. Every other human is in front of it.

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¶Orbital Refueling. Late last week, NASA signed a final $25M contract for a first LEO fuel depot that will refuel the upper stages of smallsat launch vehicles. This depot demonstration mission, LOXSAT 1, is scheduled for launch in 2023 and will be followed by mission planning for a full-scale LOXSAT2 in 2025. The contract is the second related to cryogenic fuel management for Florida-based Eta Space—the company is also assisting with a $27M 2019 Tipping Point award for development of a fuel depot capable of operation on the lunar surface. Traditionally, on-orbit fuel depots have suffered from a difficult business case where third-party vehicles don’t invest in standardized support for on-orbit refueling due to the lack of existing depots in orbit—the last thing anyone wants is to develop and launch useless hardware. Northrop Grumman’s MEV-1 & 2 have sidestepped this issue by taking over all propulsion duties for large customer satellites, but the approach of having to dedicate a shepherd vehicle for each customer won’t scale for the smallsat market. This application of NASA funding, to overcome a chicken/egg problem, is some of the highest leverage dollars the agency can deploy. LOXSAT1 will include scaled-down versions of all systems required for operation and will launch on a Rocket Lab Electron (it will also be built on their Photon satellite bus). This contract announcement follows OrbitFab’s announcement in February that their Tanker-001 Tenzing satellite refueling platform will launch later this year on a Spaceflight-organized SpaceX rideshare. OrbitFab is solving the market entry problem by developing partnerships prior to launch. They’ve partnered with Benchmark Space Systems to resupply the company’s hydrogen peroxide thrusters using OrbitFab’s in-house developed RAFTI refueling interface—the refuelable thrusters are planned for use on Spaceflight’s forthcoming Sherpa space tug. SpaceX is also developing orbital refueling for Starship with NASA’s help on a massive scale—HLS Starship missions will require multiple refueling launches of Starship tankers (Casey Handmer estimates that refueling with 12 Starship tankers would allow an HLS Starship to transport 25 tons from LEO to the lunar surface and back). LOXSAT will supply LOX and RP-1, making its technology a fit for Rocket Lab, Astra, Virgin Orbit, and Firefly (but not ULA’s high-efficiency LH2 upper stages).


A filament of glowing hydrogen imaged by the MUSE instrument on ESO’s Very Large Telescope in Chile and overlaid on the iconic Hubble Ultra-Deep Field. It is 11.5 billion light-years away and 15 million light-years long.

¶News in brief. On this day 60 years ago, overshadowed by Yuri Gagarin’s orbital flight 23 days earlier, a suborbital Mercury Redstone took Alan Shepard past the Kármán line to become the first American in space; fittingly, Blue Origin is scheduled to announce pricing for suborbital tourist flights today—they have signup info on their website; after six months in space, the four Crew-1 astronauts safely returned from the ISS in their Crew Dragon, the first nighttime splashdown of a US crewed vehicle since Apollo 8; SN15 is poised to launch any day now after multiple static fires and several scrubbed launch attempts; Vega successfully returned to flight, delivering an Airbus 30-cm imaging satellite and several smallsats to orbit—Vega’s launch failure last year, due to an improperly connected cable, destroyed two Earth observation satellites; the SLS core stage for Artemis I, now past its Green Run tests, arrived via barge at Kennedy Space Center—all components for Artemis I have now arrived and are ready for stacking; OneWeb, which just received an investment from Eutelsat, launched 36 more satellites to orbit via Soyuz, bringing their total to 182 satellites; a Long March 5B heavy-lift rocket launched Tianhe, the core module of the new Chinese space station (discussed last week), this is the first of the 11 missions to complete the station—the core stage will again be one of the largest uncontrolled reentries in recent history around May 9th; and, last week, we failed to link to a (distant, grainy) image of Perseverance taken by Ingenuity from the air during its third flight—Ingenuity flew again last week, for a fourth time, up to 5 meters altitude and 133 meters downrange and back (pictured below)—it has now begun an extended operations demonstration mission in which it will support Perseverance’s science objectives.



In celebration of the Hubble Space Telescope’s 31st birthday on April 24th, NASA released this stunning image of AG Carinae, a short-lived, massive luminous blue variable star with a surrounding dust cloud five light-years across. It is located 20,000 light-years away and is one of the brightest stars in our galaxy—it is “70 times more massive than our Sun and shines with the blinding brilliance of one million suns”.

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