¶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.
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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.
¶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.
Zhurong looks back up the ramp to its landing platform.
- A protoplanet lovingly named Theia is thought to have slammed into the early Earth 4.5 billion years ago, dislodging enough combined material to form the Moon and leaving Earth with a 23-degree tilt. A new paper (pdf) links this event to two continent-sized higher density regions of the Earth’s mantle that underlie Africa and the Pacific Ocean and suggests that these “large low-shear velocity provinces (LLSVPs)” may be denser parts of Theia that escaped reflection into space and sank into the molten Earth.
- Following up on space tourism from last week: Bloomberg Accelerate recently released a well-done video segment that reviews the current state of space tourism, and Discovery announced their Who wants to be an Astronaut? competitive adventure TV show whose winner will fly to the ISS in 2022. You can apply!
- With everyone developing communication constellations, it’s exciting to learn about Femtostar, an open-source, open-infrastructure, security- and privacy-focused midband (100s of kbps) project under early development. Their FAQ answers a lot of the obvious questions. Initial development funding is from NLnet, but you can also donate on their site. Join their Matrix room to keep tabs on the project or offer to help out.
- The US Justice Department has made it clear that ITAR compliance is not a valid reason to avoid hiring non-US Persons, they just cannot work on portions of a company’s efforts that are covered by ITAR. This separation of concerns is non-trivial for small companies, though.
- The Dark Energy Spectroscopic Instrument (DESI) started its official five-year observation run last week. With a wide field of view, DESI uses 5,000 individually-robotically-controlled optical fibers to collect spectroscopic data from 5,000 targets simultaneously. It can collect 5,000 spectra every 20 minutes and 150,000 in a good night of observation. They plan to measure the redshift and spectra of ~30 million galaxies to build a 3D map of the Universe. This is primarily to study dark energy, but as with any large survey, there could be many ancillary discoveries as well.
- Starlink review: dreams, not reality. tl;dr: The Verge blithely ignores SpaceX’s warning about a beta service needing a clear line of sight to the sky and, to their surprise, has a bad experience. They then point out that others have also ignored warnings and had bad experiences. Nonetheless, the writer makes exceptionally good points about the US broadband situation.
- Worlds with underground oceans, like Europa and Enceladus, may well be more favorable to life than worlds with oceans on the surface, as life in underground oceans is protected from most solar radiation, supernova explosions, and asteroid impacts. ☄️🦑