¶The first 60 SpaceX Starlink satellites were launched, along with a slick website (scroll down and pan left/right for satellite details). The 60 initially flat packed satellites deployed using rotational momentum (video), drifted apart, and then successfully checked in. The already twice-recovered Falcon 9 booster stuck a hard autonomous drone-ship landing after having launched the heaviest Falcon 9 payload to date. Since the launch, there has been concern from astronomers over the impact that 12,000 fast-moving LEO satellites may have on ground-based telescope observations. (There are about 5,000 satellites total in orbit right now.) Musk says the team will be looking at ways to reduce the albedo of future satellites. It remains to be seen how bright Starlink satellites are once at final altitude with their solar panels properly sun-aligned.
¶NASA is sending biological samples into interplanetary space, for the first time (intentionally) in almost 50 years. BioSentinel is a 6U cubesat to be launched into a heliocentric orbit in mid-2020 on SLS’s first flight. It will carry microfluidic cards containing yeast, a model organism whose DNA repair pathways are similar to our own. Identical samples on the ISS, protected by the Earth’s magnetic field, will provide a comparison on the yeast’s survival in the interplanetary radiation environment.
¶Water and the formation of the Moon. Much of the Earth’s water may have arrived on Theia, the hypothesized Mars-sized protoplanet that impacted the Earth and created the Moon 4.4 billion years ago, suggests a recent Nature Astronomy paper. The isotopic distribution of molybdenum in the Earth’s early mantle shows that much of it was deposited by carbonaceous chondrites (water-bearing objects from the outer solar system beyond the frost line), and since molybdenum is very dense, its presence outside the Earth’s core indicates that it arrived after the planet had solidified. Based on this timing, the authors suggest that Theia was probably the molybdenum’s source and therefore originated in the outer solar system from where it would have carried large quantities of water. Coincidentally, carbonaceous chondrite “mud balls” fell through the roof of a house in Costa Rica last month to the surprise of the (unharmed) humans inside. These samples will provide material on which we can practice asteroid water extraction. Related: The far side of the Moon, which is never visible from Earth due to being tidally locked, has a thicker crust and different composition than the near side, consistent with a later massive lunar asteroid impact (paper). Scott Manley has a recent video covering this and its relation to the Moon’s lumpy gravitational field that results in most lunar spacecraft eventually crashing.
¶Ion drives have been in the news recently, in part due to Starlink’s use of the first krypton-fueled Hall effect thrusters for orbit raising and station keeping. We thought we’d share a round-up of interesting videos:Related: NASA selected Maxar Technologies (previously SSL) to build the Power and Propulsion Element (PPE) which will perform station keeping with 50 kW electric ion thrusters for the Lunar Orbital Platform-Gateway, NASA’s upcoming partially-crewed space station in a lunar halo orbit. NASA designed the PPE at Glenn Research Center, referenced in the Science Channel clip above.
¶Other News. AWS Ground Station, Amazon’s Ground Station as a Service, is now available; a rocket built by students probably reached space for the first time (here’s a documentary video) while another multi-school student team is planning to launch next week; and a Chinese Long March 4C launch failed to reach orbit due to a third stage failure—the government-controlled news outlet report states, “Based on monitoring data, the third stage of the rocket and satellite debris have fallen on the ground.” highlighting an ongoing issue with Chinese launches taking place over populated areas.
- 507 Mechanical Movements, an animated compendium of mechanical behaviors. See also Animagraffs.
- NASA’s exhaustive Beginner’s Guide to Kites. We had no idea kites were this complicated.
- Recent 4K video test from space by Sen. (Jump to the middle of the recording.)
- Pluto may have a liquid subsurface ocean insulated by methane gas hydrates (paper). On the other hand, Io may not have an underground magma ocean after all (paper).
- Include your name onboard Mars 2020, etched 75 nanometers tall on a silicon chip — because, as we all learned in elementary school, writing your name on something makes it yours.
- The Small Bodies of the Solar System, a beautiful collection of photos of Bennu, Vesta, 67P/Churyumov-Gerasimenko, and many other small solar system bodies. Related: understanding “rubble pile” asteroids.
- The Saturn 500F: The Moon Rocket That Couldn’t Fly
- Spacelog — transcripts from early space exploration missions (Vostok 1, Mercury 3, Apollo 13) in a searchable, linkable format. One gem: “The Beatles have announced they will no longer perform as a group. The quartet is reported to have made in excess of a half billion dollars during their short musical career. However, rumors that they will use this money to start their own space program are false.” — Joe Kerwin / Apollo 13