¶11th time’s the charm. Starlink-9 finally launched 57 more satellites into its growing constellation after ten delays, bringing the in orbit Starlink total to over 500 sats. This was the first full batch of “visorsats” featuring built-in sun shades to decrease reflections from the Earth-facing phased-array antennas—the pilot visorsat that launched in June is still not at operational altitude, but SpaceX is confident enough in the improvement that they are shipping all future satellites with shades. 😎 SpaceX is now churning out Starlink satellites at a rate of 120/month. Four satellites per day is mind blowing; traditional satellite development has been measured in years per satellite, not satellites per day. The internet service, if you believe the rumor mill, is due to begin beta testing soon for early adopters in North America who live above 44° latitude and have a clear view of the sky (the “UFO on a stick” receiver and paired router have also recently been leaked). This launch also delivered two BlackSky commercial Earth observation satellites as part of SpaceX’s rideshare program. The mission’s booster landed for its fifth time (but fairings falling from orbit continue to be hard to catch). Related: Among a spate of stellar outcomes for the company, the Space Force selected SpaceX for continued launch services along with ULA, passing over Northrop Grumman and Blue Origin. |
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A leaked photo of a prototype Starlink terminal on a rooftop mount. |  |
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¶The Interstellar Probe. Planning a 50-year mission to 1,000 AU is hard. Like “Voyager on steroids”, the proposed nuclear-powered mission would go further and faster (Voyager is at 150 AU right now) to study the interstellar medium, the heliosphere, and cosmic rays unhindered by the Sun’s influence. What management structure do you use for a project that will involve multiple generations of scientists before completion? Recommendations, informed by the building of cathedrals, include taking a multigenerational approach where roles have explicit term limits, nurturing mentorships and apprenticeships, developing collective rituals, and creating plenty of documentation (including around the thought processes involved, not just the resulting decisions). These feel like actions that all big projects should be taking. This reminds us of the Greek proverb, “A society grows great when old [people] plant trees in whose shade they know they shall never sit.” (Or, a similar one in Chinese.) Related: everything from the Long Now Foundation. |
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📅¶ It’s Perseids time again. This year’s Perseid meteor shower peaked last night, but this evening (August 12/13th) should still offer a good show (if your weather cooperates) due to a waning Moon. The meteor shower’s radiant, or visual source, is located in the Perseus constellation. Look northeast for meteors streaking across the sky from that point. You can visualize our path through the source, Swift-Tuttle comet’s trail, or just find out how best to view the shower here. Astro Bob has more discussion of the shower and its source. |
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¶The future of Angara. The Angara A5, Russia’s replacement for their Proton rocket with military GEO launch capability, costs way too much and has only flown once, back in 2014. The A5, powered by the RD-191 engine (a single chamber version of the RD-170), has been in development since 1994, with the second orbital test flight scheduled for November. Similar to the more recent Falcon Heavy, the design supports strapping multiple Universal Rocket Module boosters (URM-1s) together to achieve greater lift capacity—while Angara 1.2, the other active variant in the family, employs a single URM-1, the A5 boasts four additional strap-on URM-1s. Khrunichev, the rocket’s developer, has experimented with many variants along the way, including an RD-170 powered version proposed to NASA in the early 2000s. Given this history, there is skepticism about the recent announcement of a planned Angara-A5VM variant with reusable stages. In July, Roscosmos shipped pieces of the Angara’s phase II launch pad to Vostochny Cosmodrome via the north sea route, lending credence to additional investment by Russia into the Angara vehicle family. |
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¶Papers. - The Sloan Digital Sky Survey released an analysis of the largest three-dimensional map of the Universe ever created (paper), looking at 2 million galaxies ranging from nearby to 19 billion light-years away. Their data is available online. These results support many things we think we know about the Universe, such as the isotropy (uniformity) of dark energy, a Universal energy budget of 70% dark energy and 30% normal matter + dark matter, and the flatness of space (within 0.2% of the critical density), our best measurement yet (indicating, among other things, a huge—possibly infinite—Universe). They also support a Hubble constant of 68.2 km/s per megaparsec, strongly suggesting the existence of dark energy. The oddly differing measurements of this constant remain unsolved. Ethan Siegel has a good discussion on this release.
- Due to linguistic drift, settlers on a generation ship might be speaking a different language when they arrive (paper). (They would have to be settling further away than the asteroid belt, however.)
- Even at a whopping 30 AU, Pluto appears to have a liquid subsurface ocean 100-180 km thick. Based on expansion cracks on the planet’s surface, a new paper suggests that, rather than having started out frozen and then melting due to radioactive decay, Pluto may have started out warm, with the heat of gravitational accretion, and then later radioactive decay, keeping an ocean liquid for billions of years. This suggests that “oceans could persist to the present day in the largest [Kuiper belt] objects, such as the dwarf planets Eris and Makemake.”
- A radiation shielding cream made from a combination of melanin and selenium (paper). Melanin’s radiation absorption abilities are being tested on the ISS, which is also testing a radiation-absorbing fungus that is found growing at Chernobyl for use as a “self-replicating radiation-shield” (paper). 🍄
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