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¶The search for Planet Nine continues. Two new papers (1, 2) lay out evidence for a hypothesized ninth planet of ~5-10 Earth masses orbiting deep in the outer solar system. This planet would resemble the many extrasolar “Super-Earths” that have been found in recent years and might explain the peculiar orbits of certain Kuiper belt objects, similar to how Neptune’s existence was originally predicted based on deviations observed in Uranus’ orbit. “[E]xplanations for the observed physical clustering of orbits with semi-major axes in excess of ∼250 AU, the detachment of perihelia of select Kuiper belt objects from Neptune, as well as the dynamical origin of highly inclined/retrograde long-period orbits remain elusive within the context of the classical view of the solar system.” Planet Nine is definitely not a foregone conclusion, however. Ethan Siegel has a compelling article in Forbes arguing against its necessity. One of the main researchers looking for Planet 9 is Mike Brown of Caltech who taught the excellent (and free) Coursera course The Science of the Solar System, which Andrew highly recommends. |
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¶OneWeb launched the first six satellites of their planned Internet constellation aboard a Soyuz rocket, in large part to demonstrate utilization so that the ITU wouldn’t give away their spectrum allocation. OneWeb’s 150 kg satellites orbit in LEO, giving them much better latency than the 0.5s typical of geostationary satellites. However, OneWeb will need around 600 satellites in order to provide gap-less Internet coverage, which won’t happen before 2021. Like Iridium, it will be interesting to see if OneWeb can drive enough demand for the service, on which it has already spent $2 billion. Meanwhile, SpaceX and Boeing are also working on their own internet services with planned constellations of 1000+ satellites each. |
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¶SpaceX’s Dragon 2 launches 🚀and docks at the ISS, demonstrating the company’s human-rated launch capability as well as delivering 400 pounds of supplies. Space.com has a good review. The first launch with a crew, culminating the company’s 17-year effort to put humans into space on a commercial vehicle, is currently planned for July once an in-flight test of the crew abort system has been conducted. Semi-Related: here’s a 2015 deep dive into the multi-resolution computational fluid dynamics simulations used to model SpaceX’s Dragon capsule reentry and rocket engine combustion chambers. |
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¶The Beresheet lunar lander performed its first orbit-raising burn after two glitches. Last week, the Israeli lander had star tracker problems, likely due to being blinded by the sun, then the spacecraft’s computer unexpectedly reset, causing the burn to be canceled automatically. Beresheet launched two weeks ago as a rideshare with two other satellites heading towards geostationary orbit, and, if successful, will be the first privately funded craft to land on the moon. Even with the boost of the shared geosynchronous transfer orbit, due to a low delta-v budget, the lander is spending 8 weeks getting to the moon [video], doing a series of burns at periapsis which take advantage of the Oberth effect to conserve fuel. The Planetary Society has a nice mission page for Beresheet. |
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¶In other glitches from around the solar system, Curiosity resumed science operations on Feb 28th/Sol 2333 after going into safe mode on Feb. 15. NASA has yet to ascertain the cause of the 13-day outage. An unrelated but long-term challenge for the rover has been wheel damage. Here’s a super in depth look at the damage which has led to rerouting and lighter duty cycles. |
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¶NASA’s Venus rover development program is accepting public proposals through March 31st for a clockwork mechanical camera. We’re fascinated and perplexed by the idea of recording and transmitting light entirely mechanically. The rover program features steampunk automaton designs created to deal with Venus’ harsh atmosphere (9.3 MPa pressure & 467° C temperature on the surface, not to mention sulfuric acid rain in the upper atmosphere that evaporates before it hits the ground in a process known as virga). NASA developed the Glenn Extreme Environments Rig (GEER) in 2015 to help test missions designed to survive in environments like those on Venus, Titan, and the gas giants. In a bit of a tangent, reading on this led us to find a 1985 paper and a phys.org article on terraforming Venus—one particularly appealing option is sky cities that split CO2 into carbon/graphene (for construction) and oxygen (for breathing and fuel), since this is a technology we are in need of (and are currently developing) here on Earth. |
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