Issue No. 5

The Orbital Index

Issue No. 5 | Mar 26, 2019

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H2O (in the form of hydroxyl groups) was detected on Bennu by OSIRIS-REx. This observation supports future prospects of mining water from asteroids to make fuel and/or air by baking the water vapor out of clay. Also: Bennu seems to be an “active asteroid,” ejecting streams of particles by an unknown mechanism, and its rotation is speeding up, probably due to the Yarkovsky effect in which sunlight absorbed as heat and then released as blackbody radiation from a small rotating body can speed its rotation up over time.

Reusing rocket upper stages. Blue Origin is considering repurposing the upper stages of their upcoming New Glenn rocket for use in orbit, possibly as habitats. (Development of New Glenn remains on schedule for launch in 2021.) A group consisting of NanoRacks, SSL, and ULA has also studied repurposing orbital rocket bodies as part of NASA's NextSTEP program. That proposal would involve an Atlas 5 upper stage refitted with life support and attached to the ISS or another station. Repurposing of upper stages in orbit makes sense when considering the energies involved with returning them to the ground for reuse. An upper stage may be moving at up to 8 km/s, compared to ~2 km/s for returning first stage boosters. Decelerating for reentry at those speeds requires a large amount of fuel, heat shielding, or both. The Space Shuttle and SpaceX's proposed Starship are examples of upper stages that return to Earth for reuse using heat shields (or hypothetically “transpirational cooling” in the case of Starship).

NASA's Mars 2020 rover is undergoing systems tests at JPL's Spacecraft Assembly Facility. The Mars 2020 lander is based on Curiosity, but will carry upgraded hardware and science payloads, including a number of spectrometers, sensors to detect organic compounds, an ISRU experiment that will produce oxygen from Martian CO2, ground-penetrating radar to study geology and look for buried ice, a drill to collect samples that will be left on the surface for a potential future sample return mission, and a drone helicopter (!!).

Italian hyperspectral satellite PRISMA launched on a Vega rocket from French Guiana. The launch marked Arianespace’s 600th satellite launch. PRISMA’s hyperspectral imager will collect full spectral data from the visible to shortwave infrared bands, allowing absorption spectroscopy per pixel. These features can identify signatures of minerals, soil types, and pollutants for 30x30 meter sections of the Earth’s surface. PRISMA rode to a Sun-synchronous orbit atop a four stage Vega rocket (the next generation Vega-C is scheduled to debut in early 2020 increasing lift capacity to 2,200 kg using new P120C solid rocket motors). Sun-synchronous orbits are almost-polar orbits in which the satellite passes over a given point at the same local time each day, allowing images to always have similar illumination. This is possible because the mass of the Earth's equatorial bulge torques the orbit and causes precession eastward at the right rate (~1 degree per day) to counter the Earth's motion around the sun.


“Jupiter Marble” (photo credit: Juno).

Jupiter Marble

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