The Orbital Index

Dream Chaser and Orbital Reef. Sierra Space has been in the news multiple times recently. In no particular order: 

• The company raised a Series B (odd to call it that, given its history as a public company spin-out working on a 10-year-old project, but Series B is what it has been dubbed) for a whopping $290M. This new investment valued Sierra at $5.3B and brings the company’s total capital raised (in its current incarnation) to $1.7B.
• The future of Orbital Reef, Sierra’s joint venture with Blue Origin, is deeply in question with both companies focused on other projects (Dream Chaser for Sierra and New Glenn and HLS2 for Blue). Orbital Reef hasn’t released any updates in months, and rumors of a possible break up (here and here), despite $130M in funding from NASA, are swirling. Recent leadership changes at Blue may be impacting this partnership, while on the Sierra side, the company’s latest funding being from Japanese partnerships may affect future project dynamics.
• A little while back, NASA signed an unfunded Collaborations for Commercial Space Capabilities 2 (CCSC-2) agreement with the company to leverage NASA’s technical expertise for both Sierra’s in-development, crew-capable version of its currently-cargo-only “mini-shuttle” Dream Chaser vehicle and its LIFE space station module. (While called a “mini-shuttle”, Dream Chaser’s lifting body design inherits from HL-20 vs. the Shuttle.) CCSC-2 contracts were also signed in June with SpaceX, Blue Origin, Northrop Grumman, Vast, Special Aerospace Services, and ThinkOrbital. (Northrop may also be out of the commercial space station business, based on recent reports.)
• The cargo version of Dream Chaser continues to inch toward a 2024 launch atop the second ULA Vulcan rocket. It heads to NASA Glenn in Ohio next for thermal vacuum, vibration, and acoustic testing. NASASpaceflight recently dove into the craft’s Thermal Protection System (TPS), which improves on the Shuttle’s TPS in many ways but still has individually unique tiles and will require waterproofing (possibly with dimethylethoxysilane). The craft will provide 1.75 tons of downmass with less than 1.5G of deceleration—useful for delicate experiments and on-orbit produced materials, such as organs—a capability lacking since the last Shuttle flights over a decade ago.

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• Infrasound seismometers hanging from balloons in the Venusian atmosphere could monitor underground seismic activity (paper).
• Detecting Baryon Acoustic Oscillations (BAOs) via statistical anomalies in the orientations of a million galaxies (paper). BAOs are disturbances in the distribution of matter at a massive scale due to acoustic oscillations in the primordial plasma soup of the very early Universe. An individual oscillation, nearly one billion lightyears across, may also have been spotted for the first time (pdf).
• How old are the oldest continents (‘exocontinents’) throughout the Universe? Assuming plate tectonics requires a liquid planetary core—which requires radioactive decay as a source of heat—this paper figures out when abundances of thorium and radioactive potassium had built up enough in the Universe for exoplanets to first form continents. The answer: up to 4-5 billion years before the Earth formed.
• The fastest hypervelocity white dwarf stars we’ve observed yet were found by searching through Gaia data (paper). They have relative velocities of 1,700 km/s  and 2,300 km/s—these stars were likely sent careening when their white dwarf binary partners exploded in Type Ia supernovae, and are now moving at far beyond the Milky Way’s ~550 km/s escape velocity. Needless to say, you do not want to encounter a star moving at 2,000+ km/s. ☄️
• Here’s a fun paper with a chart of all objects in the known Universe (below).

ILLUMA-T, DSOC, and laser comms. Launching in a Dragon trunk later this year as part of CRS-29, ILLUMA-T will create NASA’s first demonstration of a production-usable, end-to-end laser communications system. Once it is installed on the outside of the Japanese Kibō module, the laser terminal will beam signals from the station to LCRD (a GEO laser relay launched in 2021) and finally to a ground station in California or Hawai’i. ILLUMA-T’s infrared lasers will transmit data at 1.2 Gbps, adding a connection that is twice as fast as the station’s existing 600 Mbps radio link (LCRD also has an additional 622 Mbps Ka-band downlink). Laser comms are even more important for deep space missions where downlink constraints often force teams to throw away or deprioritize scientific data. The soon-to-launch Psyche mission is packing DSOC, a vibration-isolated deep space near-infrared laser communications link to demonstrate high-data-rate downlinking from the craft to NASA’s main optical ground station in California—over a distance of as much as 400 million km. Exact target downlink speeds haven’t been shared widely but could eventually be in the 10x to 100x range compared to state-of-the-radio-art downlinks which top out at around 4-6 Mbps from Mars (this NASA laser comms update presentation suggests a max of 267 Mbps for the DSOC terminal hardware aboard Psyche at distances <0.25 AU, but it will manage ~1-2 Mbps at mission distances approaching 2.7 AU). Similarly, LLCD set records for cislunar two-way laser comms all the way back in 2013, hitting 622 Mbps downlink with a 20 Mbps uplink. Meanwhile, closer to Earth, Starlink v2 Mini satellites just received upgraded laser crosslinks capable of up to 100 Gbps. ESA has also been investing in laser comms through its two EDRS relay satellites in GEO, which use 1.8 Gbps laser links along with a 300 Mbps Ka-band link to acquire data from satellites in lower orbits (most notably Copernicus Sentinel sats) and then downlink that data via a traditional 300 Mbps Ka-band connection.

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• Intentionally puncturing a spacecraft’s batteries at the end of its mission life to generate a hot gas jet for enhanced deorbiting.
• Project Kuiper’s upcoming ULA may be the most secretive launch this year (at least from the US). 
• In an about-face from previous indications (with help from a 7,000+ signature petition), NASA recently extended the New Horizons mission into the late 2020s, continuing as a planetary science mission. This extension will allow the spacecraft, cruising through the Kuiper Belt, to collect heliophysics data while the existing team searches for a new KBO suitable for a flyby (cf. Issue № 225).
• As we've seen with Starship, Varda, and New Shepard, the FAA (specifically the Commercial Space Transportation division) can delay launches via their licensing approval processes for both launch and reentry. This blog post explains their extensive regulatory process and emphasizes the importance of factoring in regulatory requirements early in the design stages for new launch vehicles. The FAA isn’t necessarily focused on the launch vehicle reaching its intended destination but instead wants to ensure that the launch is safe and that rockets don’t explode near people or fall on cities or homes. (h/t Scope of Work.)
• Videos of Starship being stacked by its robotic launch tower never get old.
• The Ring Nebula (below) is a well-known example of a planetary nebula, the destructive results from the end stages of a dying red giant star, which our Sun is expected to experience in ~5B years. Unrelated to planets, these nebulae form when Sun-like stars run out of nuclei available to fuse and swell while their cores shrink and can no longer hold onto their outer layers of gas. These layers are shed into space and ionized by the star’s UV light, glowing spectacularly.