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The Orbital Index

Issue No. 38 | Nov 12, 2019

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NASA’s planetary mission feasibility studies. Ahead of the 2023 Planetary Science Decadal Survey, NASA has funded 10 feasibility studies (out of 54 proposed) for future planetary missions (pdf). A subset will be developed into full mission proposals, and a select few will be funded and launched in the late 2020s and 2030s. The studies include two missions to Mars (MORIE & MOSAIC); a mission to an undecided body to study Geochronology (determination of the absolute ages of geologic events); a mission to the dwarf planet Ceres which has more water than any body in the inner solar system other than Earth, likely originated in the outer solar system, and is home to a 4 km tall mud volcano [2017 pdf paper from the same PI]; a Mercury lander; a flagship-class mission to Venus (see this video that we linked last week); a spacecraft that would orbit Pluto and then continue on to explore at least two objects in the Kuiper Belt; a mission to study Enceladus, with its life-hospitable subsurface ocean and complex organics; two missions to the Moon (the LGN lander and Intrepid, which would rove for ~1800 km on the surface); and, Odyssey, a mission to Neptune and its large, captured moon Triton which may include a Neptune probe and Triton lander—the Ice Giants are overdue a dedicated mission, given their resemblance to many exoplanets. Mars 2020 and Europa Clipper, both currently under development, were part of the last Decadal Survey.

The second Starlink launch. Yesterday, SpaceX launched another 60 Starlink satellites to LEO, making it the largest telecom satellite constellation (Planet currently operates 120+ satellites in the largest overall constellation). This launch was SpaceX's first attempt at flying a Falcon 9 booster for the fourth time, its heaviest payload to date, and its first reuse of a payload fairing (this particular fairing was fished out of the Atlantic after the April Falcon Heavy Arabsat-6A mission). The new Starlink satellites have improved steerable beam-forming phased-array antennas, can now use the Ka-band, and increase throughput compared to the first set of satellites launched in May (they are also now 100% demisable up from 95%—completely burning up upon reentry). The mission went off nominally except for SpaceX's net ships being unable to attempt re-recovery of the fairings due to high seas. This success sets the stage for an average of two Starlink launches per month and the beginning of customer service in 2020. Night sky light pollution is still a very open topic, and while SpaceX has said they are working on upgrades to decrease satellite reflectivity, this batch doesn't have those improvements—so you might be able to spot them. (Related: The next in Casey Handmer’s series of articles, entitled Starlink is a very big deal.)

Mercury transited the Sun. Another Mercury transit won’t happen again until 2032, but if you missed it, fear not, there are many, many, many pictures and videos of the event, plus a JPL article on why it’s scientifically interesting. Related: Mercury’s orbit was a bit of a mystery around the turn of the 20th century (video). During this era, a 9th planet—closer to the sun than Mercury—was proposed and given the name Vulcan to explain the small but noticeable precession of Mercury’s perihelion. It wasn’t until Einstein’s theory of General Relativity explained this precession that astronomers gave up their search for Vulcan.

News in brief. A Long March 4B launch used very SpaceX-esque grid fins to guide the first stage away from populated areas and to study future reusability; an upgraded Antares rocket carried 15 small satellites and 3705 kg of cargo to the ISS; ESA’s Solar Orbiter has arrived at KSC for testing ahead of a February launch⁠—the Solar Orbiter will use a resonant orbit with Venus to slingshot itself into an increasingly inclined orbit of up to 33° to image the Sun’s poles for the first time; TESS is moving on to survey the northern sky after completing its southern sky survey, returning 20 terabytes of data on 29 exoplanets and 1,000 candidates (and starting a partnership with Breakthrough Listen to look for aliens); as a new potential NASA funding bill became public supporting SLS and the ISS (through 2030), the White House Office of Management and Budget sent a letter to congress again asking for Europa Clipper to launch on a commercial vehicle instead of SLS, saying that “at an estimated cost of over $2 billion per launch for the SLS once development is complete, the use of a commercial launch vehicle would provide over $1.5 billion in cost savings” (meanwhile, NASA recently rejected a proposal from Blue Origin for a cheaper SLS upper stage design).


60 of SpaceX’s latest Starlink satellites flat stacked and awaiting launch.