Issue No. 167

May the 4th be with you!

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The Orbital Index

Issue No. 167 | May 4, 2022

🚀 🌍 🛰

Rocket Lab catch and release. On Monday, Rocket Lab came within a whisker of becoming the second private company to successfully recover an orbital class booster (video). Unlike SpaceX, Rocket Lab is avoiding the complexity and slow support equipment turn around cadence of ship-based propulsive landings by accepting a small additional mass for recovery hardware and tackling the logistical difficulty of a mid-air catch. The catching aircraft, a Sikorsky S-92 helicopter modified with an auxiliary fuel tank for longer flight times, is capable of carrying 19 people, or one small rocket booster (dry mass ~1 ton, well below its ~8-ton max payload minus the capacity used to carry extra fuel). The company’s 19th mission, aptly named “There and Back Again,” launched successfully, deployed its payload of 34 smallsats, and the booster re-entered for a catch attempt 240 km off the coast of New Zealand. A drogue chute on the first stage deployed at 13 km in altitude, followed by the main parachute at 6 km, reducing the necessary catch speed to ~10 m/s for a long catch hook attached to the bottom of the S-92. Unfortunately, the team was not comfortable with how the booster was flying after the successful catch so they released it from the helicopter to splash down into the Pacific Ocean, where it was fished out by a support vessel. Despite the unplanned release, this is a huge milestone in Rocket Lab’s quest for reusability, which the company says is required to provide a launch cadence that meets burgeoning industry needs. Meanwhile, the 34 sat payload contained three small, low-profile GNC prototypes for E-Space—the startup proposing to launch a hundred thousand “sustainable” satellites (cf. Issue 156)—as well as satellites from Alba Orbital, Astrix Astronautics, Aurora Propulsion Technologies, Unseenlabs, and Swarm Technologies.

Just about hooked: the Electron first stage from the company’s “There and Back Again” mission during recovery. Credit: Rocket Lab

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GNSS Radio Occultation. We covered Radio Occultation (RO) weather monitoring back in Issue 111 when we discussed NOAA starting to purchase this data from GeoOptics and Spire. When a radio signal passes through a planet’s atmosphere, it refracts (bends) proportional to the air’s temperature, pressure, and moisture content. RO takes advantage of this effect, measuring the Doppler shift of a received signal (usually from a GNSS source like GPS satellites) as the satellite falls over the horizon of the Earth into eclipse. RO was originally used by Mariner IV to detect the existence of the Martian atmosphere in 1965. More recently, NOAA’s 6-satellite RO constellation COSMIC was able to improve typhoon path prediction by 24%—its successor, COSMIC-2, launched in 2019. Now startups like GeoOptics, PlanetIQ, and Spire are enabling large-scale gathering of RO data, selling it to NOAA and others. And you can join the party: Android users can join ESA’s CAMALIOT project by using their smartphones’ GPS receivers for RO data gathering and ionospheric tracking. ESA hopes the dataset will allow machine learning models to predict atmospheric water vapor trends, ionospheric behavior relevant to space weather prediction, and possibly provide GNSS accuracy improvements. Older Android phones will work, but newer ones with dual-frequency receivers will provide better data. Help analyze the atmosphere with your cell phone!

News in not-so-brief. We’re trying a list format this week. Let us know what you think.



On April 2nd, from the surface of Mars, Perseverance took this absolutely sublime video of Phobos transiting the Sun. You should definitely experience it (before the Martian moon reaches its Roche limit and breaks apart… in about 20 million years).

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