Issue No. 230

The Orbital Index

Issue No. 230 | Aug 9, 2023

🚀 🌍 🛰

DSS-43 and Voyager 2 Reconnect. NASA erroneously commanded Voyager 2 to point its high-gain antenna two degrees away from Earth on July 21, causing a loss of communication with humanity’s oldest functioning ultra-deep space probe. The spacecraft is now 18.5 light-hours away (>133 AU; the second most distant human-created object after its 16-day younger twin Voyager 1 at >160 AU). While the agency nervously waited for an anticipated automatic reset of the antenna’s pointing using the onboard Canopus star tracker—not scheduled to happen until October 15—efforts were made to confirm that the craft was still functional. Voyager 2’s trajectory (below) puts it in the southern sky making Canberra, Australia the only DSN facility with line-of-sight to the craft. The site’s largest antenna, DSS-43, is now 50+ years old and was upgraded in 2020 (causing an 8-month gap in our ability to command Voyager 2, during which science data was received by some of the site’s smaller antennae). This massive 70-meter dish was able to detect a faint carrier signal from the craft on August 1st despite its off-target aiming. On August 2nd, DSS-43 transmitted what was almost certainly its most powerful message ever to Voyager 2, at 143 dBm EIRP and a real power of 100kW (after line and connector losses… transmitter power was higher), instructing the craft to reorient back towards Earth. A tense 37 hours later, the Canberra CSIRO team received science and telemetry data from Voyager 2, completing the restoration of two-way communications and indicating continued nominal operations and trajectory for the 46-year-old craft. Phew. 😮‍💨

Voyager 2’s skypath amongst the southern hemisphere’s constellations, 1977 - 2030.

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Luna 25. Russia’s first post-Soviet Moon mission, Luna 25, is prepared for launch on a Soyuz this week (interview video). Luna 24 was launched in 1976, 47 years ago, by the Soviet Union (just a year before Voyager 1 & 2!) and returned 170 g of lunar material containing the first samples of lunar water to Earth. Luna 25 was conceived in the 1990s, developed primarily during the 2010s, assembled and tested in 2021 with a 2022 launch date, and then delayed multiple times due to technical issues and the removal of an ESA landing camera in response to the Russian invasion (replaced perhaps by radar). The 800-kg lander carries ~30 kg of payload to the lunar surface composed of 9 scientific instruments, including a 1.6-meter sampling arm that can reach ~25 cm below the surface. This arm will extract subsurface samples to test with a laser spectrometer for elemental analysis. Also on board are neutron and gamma-ray spectrometers (to analyze those samples), cameras, and dust detectors. The nominally-one-year-mission’s not-quite-polar 70° South landing near Boguslavsky crater may well find underground water ice (a polar landing was ruled out due to engineering constraints). Russia will be evacuating a small village (Shakhtinskyi, population: 26) due to the small possibility of a booster landing on it—purportedly taking the citizens to a launch viewing area and feeding them breakfast.

Luna-25 is attached to its Soyuz upper stage. Credit: Roscosmos

Weird Papers
  • When gravitational wave telescopes reach sufficient sensitivity, they will be able to probe the interior of the Sun by observing how waves originating from pulsars lens through and around our star (paper).
  • Meanwhile, gravitational wave telescopes are already so sensitive that they have to account for ocean waves on distant shores. This ‘microseismic motion’ was studied by the KAGRA team and was mostly predictable based on ocean wave data from 13 coastlines in Japan (pdf).
  • Are some of the galaxies detected by JWST in the early Universe actually “dark stars” powered by the annihilation of dark matter (paper)?
  • If light loses energy over time and physical constants can shift, then maybe the Universe is twice as old as we thought, explaining the seemingly-mature galaxies that JWST is seeing with redshifts that would place them just after the Big Bang (paper). OTOH, tweak theories are weak theories.
  • Directed transmissions from NASA’s Deep Space Network to deep space probes are powerful enough to be detected at nearby stars. Signals sent to Voyager 2, Pioneer 10, and Pioneer 11 have already encountered at least one star, while those sent to Voyager 1 and New Horizons will encounter their first stars soon (paper). “The earliest we can expect to receive a returned transmission from potential intelligent extraterrestrial life encountered by Voyager 1’s transmissions is 2109.” 👽

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News in brief. Starship conducted its first static fire of Booster 9 with the “upsidedown shower head” water deluge system activeThe very last Northrop Grumman Antares 230 launched to the ISS, ending the era of Russian RD-181 engines on NG’s launch vehiclesPrivateer Space may be pivoting into a satellite data marketplaceAirbus is replacing Lockheed Martin as Voyager Space’s primary partner on their Starlab commercial space station, initially funded for $160M by NASA in 2021 India’s Chandrayan-3 was successfully inserted into lunar orbit Space Command HQ is staying in Colorado Springs, after Biden overturned a Trump decision to relocate it to Alabama Some workforce reductions occurred at Planet and Astra Astroscale started their first commercial partnership—Astro-Digital will use Astroscale’s docking plate to enable on-orbit servicing on an upcoming small sat Rocket Lab’s 40th Electron rocket mission “We Love the Nightlife” was scrubbed multiple times, first due to engine issues, then strong winds, and lastly for “out of family sensor data” Euclid, now at L2,  sent back its first test images.

In this image, the light from Euclid’s telescope passed through a ‘grism’ before it reached the detector. A grism  splits light by wavelength, smearing each star or galaxy into vertical streaks of light. These spectra allow us to determine compositions, which can correspond to an object’s age and distance. Credit: ESA


Neptune (in haunting false color), imaged in January 1996, is the last planet Voyager 2 visited before heading toward interstellar space. This is the only time humanity has visited the ice gian

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