Issue No. 99


The Orbital Index

Issue No. 99 | Jan 13, 2021

🚀 🌍 🛰

The first four Pioneers. NASA’s new Pioneers program, unveiled in 2020, selected its first four mission concepts for additional development. Pioneers, not to be confused with Pioneer, focuses on conducting meaningful astrophysics research on relatively small budgets (up to $20M) by leveraging more standardized hardware developed in the SmallSat world.

  • Aspera: a mission to study galaxy evolution by observing UV light emitted by elusive "warm-hot" gas in the circumgalactic medium. “Warm-hot” gas is a hard to observe type of gas due to its faintness but makes up a large part of galactic mass during formation. Aspera, which would be the only space-based instrument capable of observing UV other than Hubble, comes from the University of Arizona and will be run by Carlos Vargas, a postdoc who is one of the youngest PIs in NASA history.
  • Pandora: a SmallSat-based telescope mission that will “observe exoplanets and their host stars with long-baseline, multiwavelength observations to disentangle star and planet signals in transit spectra.” This helps separate stellar activity (like flares) from the exoplanet itself—currently a limiting factor in the use of spectroscopy to learn about exoplanet atmospheres.
  • StarBurst: a mission to detect high-energy gamma-ray emissions from neutron star mergers. We've only detected one of these events previously, but StarBurst should be able to observe up to 10 annually.
  • PUEO: An antarctic, balloon-based mission designed to detect ultra-high energy neutrinos (for a neutrino refresher, see issue #46). These neutrinos are the fingerprints of similarly high-energy astrophysical sources such as black holes, relativistic jets, gamma-ray bursts, pulsars, and neutron stars. PUEO, if ultimately selected, would have the best sensitivity yet to neutrinos at ultra-high energies.

A rendering of PUEO hanging from its balloon (pdf) with its 120 dual-polarization antennas. PUEO is based on ANITA, a previous neutrino-observing balloon project.


What are perchlorates? Mars’s regolith is full of toxic perchlorates, chemicals that contain the ClO4- ion. Industrially, perchlorates are used as powerful oxidizing agents in rocket propellants, fireworks, and explosives, and to control static electricity in food packaging. The Phoenix lander found that approximately 0.6% (by weight) of the Martian regolith is perchlorate, probably as a mixture of calcium perchlorate and magnesium perchlorate that has formed due to exposure of chloride minerals to UV light. These chemicals have been detected by Curiosity as well. While useful as a potential source of oxygen on Mars, perchlorates are toxic to the thyroid gland, where they inhibit iodine uptake and may lead to hypothyroidism and goiter. Some limited studies of people who work with perchlorates did not find strong evidence of disease (detailed toxicology pdf), but more recent work does suggest toxicity. Like most chemical hazards, these will be both a resource and a health challenge to be mitigated. However, as Casey Handmer writes, “Perchlorates probably don’t make the list of the top ten most likely ways to die a gruesome, premature death while living on Mars!


SpinLaunch hopes to perform suborbital tests later this year. SpinLaunch is a crazy project to throw rockets through the lower atmosphere, replacing a boost stage. Test launches might happen in the second half of the year and will target suborbital altitudes of ~100 km. They have some minor physics to contend with, though, such as a rocket and payload that can withstand 10,000G of centripetal force, the shock of transitioning from vacuum to 1 atm while moving at 1,788 m/s, and the intense heating from moving at this velocity—not to mention systems required to dissipate the 500 MJ or so of energy from the simultaneously-released counterweight. “We’ve been putting together a team of engineers who, for the most part, are too young to say SpinLaunch couldn't work.” You don’t say.

News in brief. Elon Musk is now the world’s richest person (due to a surge in Tesla stock from news that the company shipped 500,000 cars in 2020); ESA’s Director General is stepping down a bit earlier than expected; Skyroot Aerospace successfully test-fired a solid propulsion rocket stage; a Falcon 9 launched a Turkish communications satellite (and the booster landed on a droneship, natch); ESA signed a $362 million contract with Thales Alenia Space to build two modules for Lunar Gateway; Cygnus NG-14 left the ISS to conduct a 5G/Ka-band SDR communication demo and a fire experiment before burning up in the atmosphere; meanwhile, the new Cargo Dragon capsule undocked from the station and will splash down today; NASA extended the Mars InSight and Juno missions, with plans (pdf) for Juno to perform close flybys of Jovian rings and satellites; Momentus Space pushed back its first flight of VigorRide to later this year to complete licensing (and signed an agreement with a Norwegian university to launch their 2U SelfieSat, which takes pictures of itself displaying photos uploaded from Earth); and, SpaceX accidentally dropped and damaged a couple DARPA satellites that were set to launch on its rideshare mission later this month.

The star Antares is really, really big. Like, filling our solar system out to between the orbits of Jupiter and Saturn, big. Related: Jatan’s recent astronomical size comparison article.


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