¶Proba-3 flies in formation. ESA’s Proba-3 mission became the first set of free-flying spacecraft to maintain mm-level precision formation flying autonomously on orbit. Precision formations of this caliber are necessary for spacecraft architectures that involve precise sunshading, like Proba-3, and will also be needed for precise on-orbit assembly, synthetic aperture optical imaging, and space-based gravitational wave detectors. Proba-3 launched in December on an ISRO PSLV-XL rocket to a highly elliptical orbit (600 km perigee, 60,500 km apogee). While at apogee, far from the influences of Earth’s gravity, the pair of small sats navigate to 150 meters apart and maintain their formation using the laser-based Fine Lateral and Longitudinal Sensor (paper), which bounces light off a retroreflector on the secondary spacecraft. Initial targeting and positioning are done via flashing LEDs and an optical wide-angle camera, with more precise alignment refined using a narrow-angle camera. As ESA fine-tunes this newly realized formation flying capability, the mission’s focus can turn to Sun observation with the ASPIICS onboard coronagraph test instrument (used while in formation with the occulter spacecraft to observe our Sun’s inner corona close to the solar limb while limiting stray light) and radiation measurement with the 3DEES payload. |
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 | Proba-3’s two formation flying spacecraft. The occulting craft flies on the sunward side of the coronagraph spacecraft, casting a carefully-controlled shadow on the coronagraph instrument. Credit: ESA |
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¶Short Papers- Based on Chang’e 6 samples, the Moon’s huge and well-preserved farside South Pole-Aitken basin is 4.25 billion years old, formed in a massive impact event (paper), only about a quarter billion years after the Moon itself formed, and 320 million years after the formation of the Solar System.
- Thermal data from Chandrayaan-3 on the Moon measured by its Surface Thermophysical Experiment probe found higher surface temperatures than expected due to locally sloping terrain, which provided increased Sun exposure at the lander’s near-polar latitude. Based on this data, models suggest that pole-facing slopes greater than 14° in this region could have temperatures capable of harboring water ice, potentially providing unexpected additional resources on the Moon’s poles (paper).
- Mars’s magnetic field is very different between its northern and southern hemispheres, first noticed by the Mars Global Surveyor mission in 1997. Recent simulations suggest that this is best explained by early Mars having had a liquid core (as opposed to Earth’s solid core) with significant differences in initial temperatures between the northern and southern halves of the planet’s mantle, for as yet unknown reason(s).
- Based on a lack of water in volcanic gases detected on Venus, there is likely little water under its surface, and it was probably never a wet world (paper). NASA’s DAVINCI mission will hopefully tell us more. (Unless canceled… 😒)
- Observing the dimming of a star as it passed behind Uranus in April allowed scientists to measure the ice giant’s stratospheric temperature, density, and pressure. This stellar occultation was viewed by 18 observatories around the world.
- Exoplanet 2M1510 (AB) b orbits two brown dwarf stars simultaneously, and very unusually, it does so in a polar orbit perpendicular to its stars’ orbital plane (paper).
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 | An exoplanet orbiting (orange line) perpendicular to the orbital plane of its two-star solar system (blue lines). |
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| ¶News in brief. Australian startup Gilmour Space will attempt launch on Thursday—their three-stage Eris rocket could make history as Australia's first domestic orbital launcher ● Inversion Space completed the first flight of its Ray reentry vehicle… which didn’t try re-entry due to a short circuit in its propulsion system, leaving it at ~500 km altitude ● iSpace’s Resilience lunar lander entered lunar orbit ahead of a landing attempt in June ● Space resources startup Interlune unveiled a full-scale prototype of their lunar excavator for Helium-3 (currently valued at $20M/kg), but it feels like there are still a lot of steps between here and extraction, let alone terrestrial return ● Rocket Lab’s Neutron rocket was selected for an experimental cargo delivery Air Force mission ● IonQ, a quantum computing firm, bought SAR satellite operator Capella Space for ~$311M in stock, seemingly for defense customers and space hardware/expertise as they develop a space-based quantum key distribution network—this remains a very odd transaction, especially since Capella has previously raised $320M in capital ● ESA and ISRO announced new cooperation initiatives involving human space exploration in LEO, and later potential lunar missions ● The FAA granted environmental approval for up to 25 Starship launches at Starbase a year, a five-fold increase from the previous limit ● Speaking of Starbase, voters approved its incorporation into a city that will be run by three SpaceX employees who won unopposed elections ● JPL’s director, Laurie Leshin, stepped down and will be replaced by David Gallagher, currently associate director for strategic interaction ● NASA canceled its commercial solicitations to launch and operate VIPER at no government cost, returning to the drawing board for resusscitating the cancelled mission ● Solar cell developer mPower raised a $21M Series B to scale production of its core product, DragonSCALES, a flexible, lightweight mesh made of silicon solar cells ● China launched a trio of military satellites ● Due to budget cuts, NASA might scale back ISS operations, such as reducing crew size, extending crew missions, and halting upgrades to the Alpha Magnetic Spectrometer science instrument ● The Trump administration plans to revive the National Space Council, despite rumors that it would be axed due to SpaceX lobbying ● After 53 years in orbit, the failed Soviet Venus lander Kosmos-482 reentered over the Indian Ocean according to Rocosmos and is likely lost (however, other tracking agencies predicted different reentry locations—here’s an overview). |
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 | Telescopic images of the failed Venus probe Kosmos 482 in Earth orbit suggest that the probe’s parachute may have deployed at some point. Credit: Ralf Vandebergh |
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A video of the 12-meter diameter antenna on ESA’s Biomass deploying in space. Biomass, which we covered recently, will use polarimetric and interferometric SAR to penetrate dense canopies to directly sense woody biomass—trunks, branches, and stems—that store the majority of terrestrial carbon at ~200 m spatial resolution. |  |
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