Issue No. 79

The Orbital Index

Issue No. 79 | Aug 26, 2020

🚀 🌍 🛰

Match Point. After learning to orbit in microgravity (0.00009807 m/s²) and making a 5 cm/pixel global map of Bennu (the highest resolution orbital mapping of any planetary body, including Earth), OSIRIS-REx just performed its last dress rehearsal before gathering a sample from Bennu in October. This dress rehearsal maneuver took the craft down to 40 m and resulted in high resolution images of the site. October’s sampling maneuver will use optical navigation (pdf) to slowly bring the craft down, with minimal thruster firings to avoid contaminating the surface with hydrazine propellant. The craft will briefly touch down, dissipating momentum in the spring-loaded Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm (animation video), and fire a burst of nitrogen to blow particles into its sample collection head. These samples will eventually make it back to Earth in fall of 2023. Here are many more details on OSIRIS-REx’s technology. Related: Both Bennu and Ryugu—recently sampled by Hayabusa2—may be composed of fragments from the same larger body (paper)—see the animation in this article

New Line Baby. Chinese startup Linkspace performed a successful 300 m vertical takeoff, vertical landing (VTVL) test last week akin to early SpaceX Grasshopper tests. The rocket, dubbed ‘New Line Baby’ (or RLV-T5) is a liquid-fueled, 8.1 m tall test rocket which previously performed a 40 m hop in April of 2019. Days after releasing video of the hop, the company released a teaser video for its big sibling rocket, SRV-1, a 15 m tall reusable suborbital vehicle. Linkspace’s first orbital class rocket, the New Line-1, is planned to eventually complete the company’s iterative approach to achieving a VTVL reusable small launch rocket lineup. LinkSpace was founded in 2013 and was one of the first of the growing number of private Chinese aerospace companies—it’s worth noting, though, that a significant number of these companies have investments or close ties to state-owned entities.

Mars Update. The Hope Mars lander successfully performed its first trajectory correction maneuver. Meanwhile, Perseverance performed one too—we recommend following @PercyRover for timely and entertaining updates en route. You can use NASA Eyes to see Perseverance’s current location (may not work on all browsers—there’s also an app). Jonathan McDowell tweeted an analysis of deep space radar data that shows the three Mars-bound craft just beginning to separate from the third stages that inserted them into their Mars transfer trajectories. The traditional Mars transfer has Earth trailing Mars at launch, catching up, and then ending up ahead of Mars by craft arrival—see porkchop charts for visualizing time vs delta-v (video). Also Mars: New research in Nature suggests that many of the planet's valley networks may have been formed by water under glacial ice sheets, not by free-flowing rivers, “throw[ing] cold water on the dominant ‘warm and wet ancient Mars’ hypothesis”.


News in brief. The ISS’s three current crew members spent the weekend in the Zvezda module to facilitate tracking down a small, but slowly growing, air leak that was originally detected last September; SpaceX is raising $1.9 billion in a funding round valuing the company at nearly $46 billion (SEC filing); Raptor engine tests recently passed 330 bar, a record for a full scale engine; Northrop Grumman’s OmegA rocket is likely cancelled; the Blue Origin-led ‘National Team’ delivered a first mockup of their lunar lander to NASA; China is proposing an international lunar research station; China also launched another Earth observation satellite; and, 2020 QG, a 3-6 m wide asteroid, flew past the Earth at a distance of just 3,000 km, making it the closest known miss of any asteroid, and it was unfortunately only spotted after the fact—for comparison, the Chelyabinsk meteor which airburst with approximately a 500 kiloton yield (~30x the Hiroshima nuclear blast) was roughly 20 meters across.

Asteroid 2020 QG's path relative to the Earth and Moon.



Congratulations to whoever wished for revenge on a forest near the Tunguska River, a 1980 Chevy Malibu in Peekskill NY, Alabama resident Ann Hodges, every building in Chelyabinsk with glass windows, and the non-avian dinosaurs.

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