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EARTH PHOTOBOMBS THE BAD SIDE OF THE MOON

LINK THE FOLLOWING: Chinese space engineers, professors and students at China’s Harbin Institute of Technology, Dutch amateur radio astronomers, and Bernie Taupin.

Back in 1970, poet/lyricist Bernie Taupin wrote “Bad Side of the Moon.” Elton John put it to music, and, together with guitarist Dee Murray and drummer Nigel Olsson, they made it famous in the album 17-11-70. Our Yank calendar convention calls it 11-17-70. This November 11, 1970, radio broadcast was Elton John’s first performed before an audience, and led to only his fifth album. According to Wikipedia, “… he believes that this recording is his best live performance.”

Fast forward to 2018 and China launching its DSLWP-B/Longjian-2 satellite into lunar orbit. The satellite built at Harbin Institute of Technology includes a tiny radio transmitter with a webcam the size of a smartphone camera. Images from the satellite began last October and were made accessible to radio astronomers around the world, including amateurs at the Dwingeloo Radio Observatory in the Netherlands.

It’s premature to judge, but these achievements by Chinese space engineers, Harbin professors and students, and Dutch amateur astronomers may well be among their “best live performances.”

The Longjiang-2 did more than deliver the camera into lunar orbit. It was one of two microsatellites launched by China last year in preparation for its Chang’e 4 lunar lander/rover which touched down on the far side of the moon on January 3, 2019. Longjiang-1 failed to achieve lunar orbit, but Longjiang-2 did so and has been successfully observing the moon since May 2018. Its DSLWP moniker stands for Discovering the Sky at Longest Wavelengths Pathfinder.

A DSLMP developed at China’s Harbin Institute of Technology.

According to space.skyrocket.de, the DSLMP weighs 45 kg (100 lb.) and was inserted into a highly elliptical lunar orbit of 200 x 9000 km (125 x 5600 miles).

The satellite’s first images were transmitted to Earth in October 2018. Douglas Heavan’s October 12, 2018, New Scientist article, “Amateurs Used a Chinese Satellite to Photograph Earth and the Moon” described details: “When Earth and the moon lined up, a group of radio enthusiasts sent the command to take the shot, downloading the image to Dwingeloo Radio Observatory in the Netherlands.”

One of the October 2018 images from New Scientist. Source: MingChuan Wei, Harbin Institute of Technology.

For a while, keeping communications optimized for the Chang’e lunar landing took priority until early February 2019.

Just the right image was captured on February 3, 2019, when the complete far side of the moon was photobombed by Earth.

Earthrise, from the bad side of the moon. This and other images from Hanneke Weitering’s “Earth Plays ‘Peekaaboo’ with the Moon in This Awesome Far Side Time-Lapse Video” February 7, 2019.

Weitering writes, “The term ‘dark side of the moon’ is really a misnomer for the moon’s far side—just because we can’t see the far side from Earth doesn’t mean that the sun never shines there. Longjian-2 captured this photo during the new moon, when the Earth-facing side of the moon was completely dark and the far side was entirely illuminated instead.”

The Dwingeloo Radio Observatory, 80 miles northeast of Amsterdam, had previous fame: It was once the world’s largest steerable radio telescope, but only for a year after its 1956 completion. England’s Lovell Telescope took the honor in 1957; the Lovell is now the world’s third largest steerable radio telescope, after West Virginia’s Greenback and Germany’s Effelsberg.

The Dwingeloo Radio Observatory. Image by Uberprutser.

Radio telescopes are much larger than optical telescopes; this, to capture wavelengths about 100,000 times longer than those of visible light waves.

Indeed, there are decidedly larger single-dish radio telescopes: Puerto Rico’s Arecibo (1963) and China’s (2016) FAST, each built in a geographical depression known as a karst. An even larger radio telescope is New Mexico’s Karl G. Jansky Very Large Array (1980). The VLA has 27 radio telescopes functioning in unison along a giant Y with a maximum collection area of 5.1 sq. mi.

Excellent Use for an “Old” Site. Dwingeloo ceased official operation in 2000 and was named a Dutch national heritage site, a rijksmonument, in 2009. The facility was restored in 2012 and is now available to amateur astronomers and radio enthusiasts. One feature employed is “moonbounce,” in which radio signals from one Earth location are beamed to the moon and then detected by an antenna at another location on Earth.

Even more dramatic were the Longjiang-2 images: Back in October, Tammo Jan Dijkema, one of the Dwingeloo volunteers, said, “We could see the image building up line by line and it was not certain that Earth would be in view, or that the exposure would be correct. When we saw the blue marble popping up, we were very happy.”

By early February, Earth was getting increasingly good at photobombing Bernie Taupin’s bad side of the moon. ds

© Dennis Simanaitis, SimanaitisSays.com, 2019

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