Space

The Breakthrough Starshot program has gotten a lot of press for planning to accelerate tiny (a few grams) probes to 10-20% C with powerful laser pulses, but a new idea proposes building a giant particle accelerator in space to push much larger probes (up to 1000kg) up to speed with a relativistic electron beam. Such a setup might get a large-ish probe to Alpha Centauri within 40 years.

NASA's Mars Exploration Program

Credits: NASA / JPL-Caltech / MSSS / 360pano.eu

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"Whether or not the moon is a planet actually depends on who you ask," Skylar Grayson, an astronomer at Arizona State University, told Live Science. The 2006 IAU definition "draws a fairly arbitrary line between planets and dwarf planets that (in)famously led to the demotion of Pluto," she added. "Some planetary scientists thus elect to consider different definitions of planets, some of which include Pluto and the other dwarf planets, and others that even include the moon."

And yet a team of amateur astronomers in the Netherlands was able to receive Voyager's signals on a 1950s telescope designed to detect weak, low-frequency emissions from deep space: NASA uses the [Earth-based] Deep Space Network (DSN) to communicate with its spacecraft, but the global array of giant radio antennas is optimized for higher frequency signals. Though NASA's DSN antennas are capable of detecting S-band missives from Voyager — it can also communicate in X-band — the spacecraft's signal can appear to drop due to how far Voyager is from Earth. The Dwingeloo telescope, on the other hand, is designed for observing at lower frequencies than the 8.4 gigahertz telemetry transmitted by Voyager 1, according to the C.A. Muller Radio Astronomy Station... [W]hen Voyager 1 switched to a lower frequency, its messages fell within Dwingeloo's frequency band. Thus, the astronomers took advantage of the spacecraft's communication glitch to listen in on its faint signals to NASA.

The astronomers used orbital predictions of Voyager 1's position in space to correct for the Doppler shift in frequency caused by the motion of Earth, as well as the motion of the spacecraft through space. The weak signal was found live, and further analysis later confirmed that it corresponded to the position of Voyager 1. Thankfully, the mission team at NASA turned Voyager 1's X-band transmitter back on in November, and is currently carrying out a few remaining tasks to get the spacecraft back to its regular state. Fortunately, radio telescopes like Dwingeloo can help fill in the gaps while NASA's communications array has trouble reaching its spacecraft.

cross-posted from: https://lemmy.world/post/23121714