Issue No. 7

The Orbital Index

Issue No. 7 | Apr 9, 2019

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Amazon is planning to launch 3,236 satellites. It was confirmed this week by GeekWire that Amazon is entering the new space race. Project Kuiper, an Amazon subsidiary, filed with the ITU to build a constellation totaling 3,236 satellites at three different LEO altitudes with the goal of offering worldwide Internet service. Amazon joins Starlink and OneWeb in the race to develop low-latency LEO internet satellites. Amazon hired SpaceX’s former VP of satellites, and Starlink lead, to run the project. Based on regulatory filings, Project Kuiper is apparently about two years behind the other two projects. It seems like no coincidence that Amazon is also building a ground station network as part of AWS.

Plasma Braking and Electric Solar Wind Sails. Andrew interviewed Andris Slavinskis and Hendrik Ehrpais about electric sails (E-sails) and ESTCube-2, a planned Estonian cubesat mission that will test a number of technologies, most notably plasma braking. Plasma braking involves dragging a charged wire (tether) through the ionosphere to generate resistance. This resistance enables deorbit without fuel, and could allow more decommissioned satellites to avoid becoming space debris. E-sails are similar in principle to plasma braking, and are planned to be tested in a future mission which will use an E-sail to perform cubesat maneuvering and station keeping in lunar orbit. E-sails, invented by Pekka Janhunen in 2006, use one or more positively-charged (~10kv) kilometer long thin wires to reflect the predominantly positively-charged solar wind, generating thrust. An electron gun is used to remove electrons from the system, creating the required net positive charge. (They said the thrust from the electron gun itself is negligible.) The main advantages over “traditional” solar sails, which use photon pressure, are engineering simplicity—it’s easier to spin out a wire than to deploy a large sheet—and the ability to function further into the outer solar system due to how the electric field expands as solar plasma gets thinner (resulting in a slower thrust fall off with distance). The previous ESTCube-1 mission was supposed to test this technology in 2013, but the motor used to unfurl the wire failed to function, probably due to damage caused by launch vibrations (space is hard!). One of ESTCube-2’s main challenges will be attitude determination while spinning at 1 rpm—a situation most satellites try very hard to avoid. Most star trackers and other attitude sensors don’t work when rotating quickly, but ESTCube-2 will need to overcome these challenges to use centrifugal force to deploy its weighted tether. We’ll keep you updated as ESTCube-2 gets closer to launch. (Please tell us what you think of our first piece of original content!)

Hayabusa2 bombed the asteroid Ryugu. JAXA’s spacecraft released a baseball-sized copper explosive-propelled impactor and a free-floating camera (DCAM3) above Ryugu this week, then waited behind the asteroid for the 7240 km/h impact (here’s a test video). The orbiter will soon return to the crater and gather a sample to carry back to Earth. Ryugu is believed to contain 4.6 billion-year-old organic compounds and water from the beginning of the solar system. This impact is the latest in an already successful mission that has fired small projectiles, dropped hopping-rovers and a lander, and touched down to gather material samples.

The ESA has set up a dedicated CubeSat development unit. The ESA’s new CubeSat Systems Unit at ESTEC in the Netherlands was announced this week, with a focus on industry partnerships, miniaturized technology, and systems integration. The nine missions currently under development include M-ARGO, a solo cubesat mission for asteroid exploration, and RACE, an attempt to dock two cubesats together in orbit. Aside: just as the rise of cell phones resulted in miniaturized technologies that have enabled cubesats, we wonder which miniaturization advances will be transferable from self-driving cars. LIDAR, perhaps?

More news in brief. Beresheet has arrived safely in lunar orbit after following a complex trajectory, took a photo of the backside of the moon, and will attempt a soft landing on April 11th. SpaceX’s “Starhopper” test rocket performed its first and second tethered test fires. Parker Solar Probe (PSP) flew by the Sun for a second time (out of 24 planned approaches); it is slowly decreasing its approach distance by using a Venus gravity assist technique. Sierra Nevada (who’s Dream Chaser spacecraft we mentioned last week) gave the public a first look at an inflatable habitat it hopes will become part of NASA’s Lunar Gateway project.


  • Want to learn about Cosmology? An excellent and free online course is Astrophysics: Cosmology, taught by Paul Francis and Brian Schmidt from the Australian National University. Brian Schmidt won the Nobel Prize in Physics in 2011 for leading the team that discovered dark energy. Their whole Astrophysics series on edX is excellent.
  • NASA’s Terra satellite caught footage of the Bering Sea airburst that happened mostly-unnoticed in December.
  • A 3D visualization of the Milky Way from the perspective of the supermassive black hole at its center.
  • An excellent article from The Verge about the challenges of identifying cubesats when deployed in clusters. The USAF still cannot identify 19 satellites from the SSO-A launch back in December. Related: AstriaGraph 3D tool for orbital visualization and tracking.
  • A fun time-lapse (or slowed down version) of the Arabsat-6A Falcon Heavy booster mating (SFW). Launch is targeted for Wednesday the 10th at 6:35PM EDT. Note: that booster in the corner of the video is from the Crew Dragon DM-1 mission and is in the process of being rehabbed, likely for use in Crew Dragon launch abort testing scheduled for June.
  • Photography of space facilities, on display at a gallery in Amsterdam.
  • Ever wonder about the status of the Iranian or North Korean space programs and where their technology came from? Scott Manley has a neat 10-minute video on some of the history and their current capabilities.
  • Länta Glacier: Small and Getting Smaller
  • Exquisitely preserved animal and fish fossils found from minutes after the Chicxulub impact that probably wiped out the dinosaurs. “Some of the fish fossils were found to have inhaled ‘ejecta’ associated with the Chicxulub event, suggesting seismic surges reached North Dakota within ‘tens of minutes’.”

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