Issue No. 128


The Orbital Index

Issue No. 128 | Aug 4, 2021

🚀 🌍 🛰

Guest contribution

You have to go big to go small. Neutrinos are notoriously difficult to detect, but each time we observe them from a new source, we seem to learn something fundamental about the universe. Recently, we observed one of these nearly massless particles with a gobsmacking kinetic energy of 6 PeV (that’s 6x1015 electron volts—about 100x the highest center-of-mass energy we’ve ever produced in an accelerator here on Earth). It was spotted by IceCube, a detector at the South Pole that instruments a gigaton of ice with photosensors to look for the radiation produced when a neutrino collides with a proton or neutron in the ice. Since neutrinos seldom interact, and get rarer at higher energies, this discovery needed the absolute largest detector we could build. But astroparticle physicists are greedy: we want more neutrinos, at ever higher energies. There are lots of monstrous cosmic accelerators out there in the Universe that could be making exavolt (1018 eV) neutrinos—flaring jets of pulsars, neutron star collisions, dying stars, or jets driven by supermassive black holes. On top of that, decades ago we observed the "Oh-My-God'' particle, a 1021 eV cosmic ray whose origin we still don’t know. Neutrinos can help us disentangle these puzzles, especially when combined with gravitational-wave observations of cataclysmic sources. Relativistic neutrino interactions with ice lead to flashes of light—detectable with optical sensors—and intense radio impulses that last <1ns. The Radio Neutrino Observatory in Greenland (RNO-G) uses this second effect to dramatically increase sensitivity in a cost-effective way. Since radio waves propagate over long distances (~1 km in ice), spacing detectors by that distance lets you affordably build an enormous detector. (With this method, lunar satellites might someday turn the entire far side of the Moon into a detector; we’re already doing it with balloons over Antarctica.) Pictured below is RNO-G’s first “discovery”: a physicist riding a snowmobile whose spark plugs emitted radio pulses that lit up the antennas 100 m below the ice surface. The planned RNO-G array is so huge that it will double as the largest-ever survey of ice flow in Greenland. Look for the rest of the 35 stations coming online in the next three years, and root for neutrino observations to follow soon after. — contributed by Stephanie Wissel, a physicist and astrophysicist at the Pennsylvania State University who finds new places to put neutrino detectors. She’s often found in weird places like Greenland, Antarctica, high-elevation mountains, or hiking with her family.


Left: Christoph Welling’s photo of antennas being lowered 100 m below the surface of the ice at an RNO-G station. Right: Cosmin Deaconu’s photo of the first RNO-G station (everything but the solar panels is buried in the ice).


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A surge at Starbase. During ~24 hours on Sunday night and Monday, SpaceX installed 29 Raptor engines on Super Heavy BN4 and has now rolled it out to the launch site. This comes after a busy week that saw the completion of orbital launch tower stacking, installation of the orbital launch table (a 370-ton steel ring that the booster will mount to with many hold-down clamps), and the addition of more Starship-style fuel tanks to the methalox tank farm. For comparison, the SLS launch tower took 9 years to complete, cost $900+ million, and ended up slightly tilted (there were extenuating circumstances, but there generally are during a nine-year build). With a short list of items left to complete before attempting at a first orbital launch (a well-done animation of the orbital test flight), FAA licensing is the most likely bottleneck for progress towards a static fire, the subsequent stacking of SN20 on top of BN4, and launch. The orbital launch will see Super Heavy booster BN4 attempt a soft landing in the Gulf of Mexico off the Texas coast while Starship SN20 will continue through a partial orbit until reentering and landing in the ocean north of Hawai’i. This comes as the ​​U.S. Government Accountability Office (GAO) denied the challenges filed by Blue Origin and Dynetics around NASA’s lunar Starship award, saying that “SpaceX submitted the lowest-priced proposal with the highest rating” and that NASA lacked the funding to make more than one award. (Related: Tim Dodd just released the first of a three part series where he walks around Starbase talking with Musk about Starship’s engineering and manufacturing.)


BN4 rolls out to the launch site.


Nauka drama. After safely docking with the ISS, the 13-meter-long, 24-metric-ton Nauka module unexpectedly started firing its thrusters in an attempt to back away from the station due to a software error. Thrusting while connected to the station caused it to rotate the ISS 1.5 times over the period of roughly an hour (animation of the rotations). This loss of attitude control knocked out communications twice for several minutes as antennas moved out of alignment and potentially induced stressing vibrations to module connections, solar panels, and radiators. Attitude control was fully lost at 11:42 am, and engines on the space station's service module were fired. This was followed by a handover to the Russian Progress vehicle attached to the station, which began to fire its thrusters. This tug-of-war offset the Nauka module thruster activity, which eventually stopped after fuel supplies were exhausted. The NASA flight controller who supported the station through the emergency wasn’t even on duty but had come into the office to watch the module docking. This is the second propulsion-related incident with Nauka, which had issues with its main propulsion system after launch and reached the ISS after using backup thrusters. Notoriously delayed, Nauka was originally scheduled to launch in 2007. The attitude control loss incident also delayed the launch of Starliner so that extra safety checks could be completed on the station.

News in brief. Delayed first by the Nauka drama, and then by “unexpected valve position indicators,” Starliner’s launch is now delayed for an unknown amount of time ● The Chinese company Deep Blue Aerospace completed a rocket hop reminiscent of early SpaceX Grasshopper tests ● Inmarsat announced a planned $100 million, 175 satellite LEO constellation called ‘Orchestra’ to compete with OneWeb and SpaceX ● German company Isar raised $75 million to expand manufacturing capacity for their Spectrum small launch vehicle ● Rocket Lab returned to flight after their May launch failure with the launch of a US Space Force testbed satellite called Monolith that “will demonstrate the use of a deployable sensor, where the sensor’s mass is a substantial fraction of the total mass of the spacecraft” ● Blue Origin is reportedly working on a reusable second stage for New Glenn as an independent project codenamed ‘Jarvis’ ● Chinese company iSpace revealed renderings of a very-Falcon-9-and-Falcon-Heavy set of launch vehicle variants while the Chinese company Space Pioneer announced a ~$30 million round of funding for their under-development reusable launch vehicle—however, this appears to be far off, with a failed return to flight of their Hyperbola-1 rocket this week, which reached an incorrect orbit and failed to deploy its payloadThe Ariane 5 successfully returned to flight with the launch of two geostationary communications satellites, one with innovative (for geo sats) phased array and software-defined radio capabilities—this is good news for JWST which launches on Ariane 5 in November.
  • REFLEX aerospace is hiring a Systems Engineer, Hardware Design Engineer, and Software Design Engineer to work on largely software-defined small-sats in “beyond-cubesat” form factors, with turn-around times of a few months.
  • Salo Sciences is looking to hire a Geospatial Data Engineer to work on their Forest Observatory, a data-driven forest monitoring system focused on reducing forest fires and conserving forests as a way to fight climate change. 
Friday was the 50th anniversary of Apollo 15 landing on the Moon with the first Moon buggy.

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