Issue No. 118

A warm welcome this week to our latest sponsor, Back To Space. B2S is a for-profit impact company that works to inspire the next generation to develop an innate love of science, engineering, and space. 💫

On a personal note, early in the life of The Orbital Index, B2S did one of the nicest things ever and invited us to the Apollo 11 50th at KSC. This is just one reason why we’re helping to sponsor their upcoming charity event (see below) with some special swag. If you’ll be going, please let us know!

The Orbital Index

Issue No. 118 | May 26, 2021

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The possibility of a Europa Lander. Intense radiation from Jupiter converts ice and dust on the surface of its icy moon Europa into energetic compounds, which may cycle through the ice and ultimately be food for microbes in the ocean below. NASA has been developing a potential Europa Lander mission to look for such chemistry since 2016 (and also previously in 2005 and 2012). This mission concept proposes a 575 kg battery-powered lander with a limited (but still impressive) lifespan of 1-3 months. (An RTG-powered lander, while technically possible, is prohibitive due to cost, complexity, and planetary protection challenges.) The lander would arrive at Europa via sky-crane, in a manner similar to Perseverance, whose innovations would also provide Terrain Relative Navigation for a safe landing. The lander has collapsing legs to keep it flat on an uneven surface (pictured below). Prototype development of cryogenic surface sampling hardware has continued during the pandemic, with WFH engineers testing designs on snow and ice in their winter driveways. This sampling system would look for biosignatures and complex chemistry 10cm below the surface, where material cycled up through the ice would still be protected from Jupiter’s radiation. The mission’s final set of instruments is undecided, but will include advanced molecular sample analysis instruments (ex: mass analyzer, laser absorption spectrometer, UV imager, and long-distance Raman spectrometer), plus possibly a seismometer, magnetometer, electric field sensor (with perpendicular antenna wires shot out onto the ice by springs), cameras, and/or other sensors. One interesting component is the Terminal Sterilization System which helps ensure no biological contamination of Europa from Earth by incinerating internal hardware at the end of the mission that could harbor microbial contamination (surface components will be sterilized sufficiently by solar UV and Jupiter’s ionizing radiation environment during transit). Unlike previous years, Congress’s 2021 fiscal budget did not include language about Europa Lander, increasing the mission’s uncertainty. However, if selected for continued development, it would be able to follow shortly after Europa Clipper. Attending a recent development team workshop drove home the incredible amount of engineering that goes into missions well before they’re approved. While development work is likely applicable to other missions, we feel for the teams who build these ingenious systems without knowing if they'll ever be used. 

All these worlds are yours — except Europa. Attempt no landing there. Yeah, right.

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Back To Space is hosting a 50th-anniversary charity event in celebration of Apollo 14, the mission that represented the return to flight for both the Apollo program after the Apollo 13 disaster and Alan Shepard after his struggles with Ménière's disease. Shepard was joined by Edgar Mitchell and Stuart Roosa (whose granddaughter is part of B2S) on the third mission to reach the lunar surface. The event will feature Apollo 16 astronaut Charlie Duke presenting SpaceX with the FROM THE MOON TO MARS achievement award, signifying a passing of the baton from the Apollo generation of explorers to one of the leaders of the next. Join Back To Space at Kennedy Space Center on June 18-19 for this once-in-a-lifetime event.

Guest contribution

GRACE, the bumpy road so far. The GRACE project is a joint venture between NASA and the German Space Agency (DLR). It consists of a pair of LEO satellites on similar orbital trajectories building a high-precision temporal map of the Earth’s gravitational field by constantly measuring the distance between the pair with an accuracy of a human hair over a nominal distance of 220 km. The Earth’s gravitational field is irregular due to uneven distribution of mass, such as ice caps, ice sheets, and mountains. The project’s first satellites were launched in 2002, with a target lifespan of five years—but ended up lasting until 2017. These satellites’ main measuring systems were onboard GNSS receivers for high-precision positioning (high-low satellite-to-satellite tracking), and K/Ka-band ranging (KBR) instruments for inter-satellite ranging between the two (low-low satellite-to-satellite tracking). An amalgamation of both of these systems has proved to generate better gravity mapping results than either alone. By the end of their science mission, the pair had made some of the greatest impact on studies of climate change and our understanding of Earth dynamics to date. Prior to GRACE, in situ time-variable gravity estimates had eluded previous satellite missions—this meant climate studies required the use of multiple missions to generate reliable results. The mission showed that a significant cause of Earth’s temporal gravitational variations is due to movement of groundwater. It also inferred ~5,000 gigatons of ice loss from Greenland and Antarctica over the mission period. Starting in 2018, the first pair of satellites was replaced by a second pair, aptly named GRACE-Follow On (GRACE-FO). This second generation was furnished with upgraded instrumentation, including a new GNSS receiver and SuperSTAR accelerometer, as well as a laser ranging interferometer (LRI) intended to improve on the KBR measurements. However, preliminary GRACE-FO results were deteriorated, due to issues with the onboard accelerometers. These initial issues have now mostly been mitigated, and the new pair look set to improve on the work of their predecessors. Results from the follow-on mission so far are showing accelerated sea level rises starting in 2019.

News in brief. A ULA Atlas 5 launched the missile-warning satellite SBIRS GEO-5 and two rideshare cubesats; South Korea is planning to join the Artemis Accords; Astra signed its first commercial customer: a multi-launch contract with Planet (including launching payloads too large for Rocket 3, which means an upgrade is in the pipeline); two Indian launch startups both announced Series-A funding rounds of $11 million each—Skyroot Aerospace for their Vikram I solid-fueled vehicle and Agnikul for their Agnibaan vehicle with a liquid-fueled, single-piece, 3d-printed engine; China launched the Haiyang 2D oceanography satellite; Virgin Galactic completed a test flight of VSS Unity to 88 km with two pilots and NASA Flight Opportunities program payloads—it tested efforts to reduce EMI levels that caused an ignition hold in Dec 2020—the last successful flight to space for VSS Unity was in February 2019; and, Zhurong successfully unfolded its solar panels and rolled off its Mars lander, snapping photos along the way.


Zhurong looks back up the ramp to its landing platform.



A fresh impact crater on Mars, found by Mars Reconnaissance Orbiter’s Context Camera, and then captured in hi-res by HiRISE.

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