Issue No. 170

Here’s your semi-annual reminder to please share OI with your friends. Thank you!

Oh, and by the way, next week we’re taking our first ever Orbital Index vacation after 170 straight weeks. We’ll see you on June 8th!

The Orbital Index

Issue No. 170 | May 25, 2022

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OFT-2 looks like a success! Starliner grabbed headlines this past week with a successful launch, insertion, docking, and stay at the ISS. Later today, it should complete its mission by landing using parachutes and airbags at White Sands Missile Range, currently scheduled for 6:49 EDT. However, this second-attempt mission hasn’t been without its own set of glitches and nail biters. The insertion burn had two OMAC thrusters fail, forcing completion using a redundant thruster. There were also some concerning pump pressure readings on the craft’s cooling system—pressure had risen due to either ice forming in the coolant or the fluid thickening due to lower than expected temperatures. The mission team was able to bring coolant temps back up by rerouting coolant flow to temporarily bypass Starliner’s radiators, a novel hack praised by NASA. Finally, leading to a hold during approach and yielding some stunning photos (one below), the NASA-designed docking adapter had to be retracted, reset, and re-extended before Starliner could make its final approach to the station. Since docking, the mission has proceeded without any additional issues and once all cargo has been swapped between the craft and the station, it will depart to jettison its service module, deorbit, and land in New Mexico (or one of the four backup sites available in case of poor weather) as NASA’s second-ever on-land touchdown (OFT-1 was the first). The performance of the parachute system during landing will be of particular interest—it has yet to be certified by NASA, and failed to deploy one chute during OFT-1. Assuming a successful landing, Boeing’s Crewed Flight Test (CFT) is up next (TBD), before the spacecraft is fully human-rated and can become half of the biannual cadence of NASA’s ISS astronaut delivery.

Boeing Starliner CST-100 sits just 10 meters away from the ISS awaiting final approach while its docking adapter is reset.

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DARPA moving forward with DRACO nuclear thermal engine. Early last month, DARPA issued an RFP for the next phase of their Demonstration Rocket for Agile Cislunar Operations (DRACO) nuclear thermal engine program. This follows on their selection, one year ago, of an early engine design by General Atomics and two spacecraft concepts from Blue Origin and Lockheed Martin. Now they’re moving on to the development and assembly of the engine through a new open RFP (not limited to the aforementioned companies). They hope to have a test flight in 2026, with NASA participating out of interest for use with future crewed deep space missions, as nuclear thermal propulsion can achieve both the required high thrust-to-weight ratio and 2-5 times the efficiency of a chemical engine. One key challenge with nuclear reactors in space is the risk of contaminating Earth. While systems are designed to be safe even in the case of a launch failure, once they’ve been activated, an accidental re-entry could be a radiological disaster. We’ve written about this DARPA program a number of times, as well as NASA’s related efforts and NIAC awards. We also took a dive into the history of nuclear reactors in space in Issue 85 (which we feel is worth a re-read). Relatedly, the DIU just funded two in-space nuclear power research projects as well.

XKCD #2423

News in Brief. NASA has suspended all planned ISS EVAs due to the small water leak in ESA astronaut Matthias Maurer’s helmet during his March 23rd spacewalk Astra revealed their larger Rocket 4.0 design capable of delivering 300 kg payloads to LEO or 200 kg to SSO, nominally for $3.95 million per launch SpaceX is raising $1.7B at a $127B valuation China launched three experimental comsats on a Long March 2C Russia launched a Soyuz-2.1a with a military satellite Psyche’s launch on a Falcon Heavy has been delayed NET Sept 20 due to spacecraft software issues discovered during ground testing Both Relativity Space and ABL Space completed testing of their rockets’ second stages.



“Slope streaks” result from dust avalanches on Mars and are “triggered by vaporizing frost creating just enough pressure to loosen the dust grains, causing an avalanche” according to a new paper. The resulting avalanches “probably look something like a ground-hugging river of dust releasing a trail of fluffy material behind. As the dust travels downhill over several hours, it exposes streaks of darker material underneath.

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