Issue No. 3

The Orbital Index

Beta Issue No. 3 | Mar 12, 2019

🚀 🌍 🛰️

A rocky start for Mars InSight’s self-hammering nail. InSight, which landed on Mars in November, carries an instrument nicknamed “the mole” that is designed to hammer itself 5m into the Martian ground to study cooling of the planet’s core. The self-driving mechanism itself is quite clever. Unfortunately, while scientists expected loose regolith, the mole has run into rock or gravel that is blocking progress, at least for now. Another impressive instrument on InSight is SEIS, a seismometer that can measure tremors smaller than the width of a hydrogen atom.

The RRM3 mission is slowly progressing towards the first cryogenic liquid transfer in space, paving the way for refueling satellites. This NASA demonstration mission includes a main unit which was affixed to the ISS by Dextre (the Canadian robotic arm) upon arrival. US and Canadian astronauts recently finished assembly of the remaining components, which will allow the first transfer to happen in coming months. Orbit Fab is a startup that is working on fuel transfer as well, using an inflatable bladder, with the goal of building the first “Gas Station in Space.” (Coincidentally, the cryocoolers in RRM3 were built by a company in Ohio where we both worked during high school.)

Near-Earth Objects (NEOs) containing water may be more common than we previously thought. A new study calculates the number of accessible hydrated objects at 700 ± 350. These asteroids are easier to access (in terms of fuel cost) than a round trip to the surface of the Moon and could be valuable for in-space refueling. The study uses Ch-type asteroids, believed to contain water, as a proxy for estimating the total number of hydrated objects since ground-based absorption spectroscopy of water is confounded by moisture in the Earth’s atmosphere. Asterank is a great tool for exploring and visualizing known asteroids and includes 28 Ch-type asteroids.

Crew Dragon DM-1 endured a nominal undocking, hypersonic reentry, and splashdown to complete a significant step towards ending the Soyuz capsule's eight-year monopoly on human access to orbital space. Two interesting tidbits coming out of the mission were NASA's preference for a water landing over the SpaceX-preferred propulsive option and Musk's love of Russia's Angara rockets. Roscosmos' response to the mission was terse and viewed by some as passive-aggressive.

Like chemistry and rockets? Andrew enjoyed “Ignition!: An Informal History of Liquid Rocket Propellants” by John D. Clark more than one would expect of a book from 1972 about rocket propellants. It was dense but surprisingly hilarious. It’s now back in print (probably due to Musk calling it “fun”), but you can find a free PDF of the original online. Writing about chlorine trifluoride—one of many terrifying things people have proposed putting into rockets—Clark writes: “It is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water--with which it reacts explosively. It can be kept in some of the ordinary structural metals–steel, copper, aluminium, etc.–because of the formation of a thin film of insoluble metal fluoride[...]. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.

  • If you’re in the SF Bay Area, you should definitely join Space in the Bay and come meet up with other NewSpace startups and enthusiasts.
  • Here’s a touching memorial to Kepler by Journalist Nadia Drake, daughter of Frank Drake. Thanks to Kepler, we now know that, “on average, at least one world circles each star in the sky, and roughly one-fifth of stars probably host a rocky, Earth-size planet in an orbit where the temperature is right for liquid water to trickle, pool, and wash over its surface.” Related: a new paper (and discussion) using computer simulations to show how stellar motion could spread alien civilizations more quickly than we expect, and yet our stellar neighborhood could still be uninhabited.
  • NASA has decided to look inward. (But really, it has.)
  • Seveneves, Neal Stephenson’s recent sci-fi epic, is on sale for $2 right now. Its descriptions of orbital mechanics are quite good, probably because Stephenson worked on trajectory analysis at Blue Origin.

Hayabusa2 touches down on Ryugu and fires a tantalum bullet.
(Why tantalum? Because it’s dense, and rare enough that, if detected in the collected sample, can be categorized as contamination.)

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