Amazing Moon-Earth Photo by the Amateurs using a Chinese Satellite

Amateur astronomers in the Netherlands took an amazing Moon-Earth photo using a Chinese satellite. On May 20, 2018, China launched Queqiao lunar communications relay satellite, a key component of the upcoming Chang’e 4 lunar landing mission. During its journey to the Moon (actually Earth-Moon L2 point Notes 1), it dropped off a pair of student-made small satellites, Longjiang-1 and Longjiang-2, bound for lunar orbit called. Their purpose was testing out future radio astronomy and interferometry techniques.

Each satellite weighs just 45 kilograms (99 lbs) and measures 50-by-50-by-40 centimeters (20-20-16 inches). They both also were carrying a camera each, built by Saudi Arabia.

Unfortunately, Longjiang-1 had a problem and didn’t make it into lunar orbit. Longjiang-2, however, was successful and sent its first set of photos to the Earth back in June 2018.

Now, Longjiang-2 sent another amazing photo to the home. According to a report on New Scientist, when Earth and the moon lined up, a group of radio enthusiasts sent the command to Longjiang-2 to take the shot, downloading the image to the Dwingeloo radio observatory in the Netherlands.

The Earth and far side of the Moon as seen by the Chinese Longjiang-2 lunar orbiting spacecraft
The Earth and the far side of the Moon as seen by the Chinese Longjiang-2 lunar-orbiting spacecraft. MingChuan Wei, Harbin Institute of Technology

Tammo Jan Dijkema, one of the Dwingeloo operators says: “It felt awesome, we were cheering in the telescope. 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 a blue marble popping up we were very happy.”

Named after Chang’e, the goddess of the Moon in Chinese mythologyChang’e 4 is a planned Chinese lunar exploration mission, to be launched in December 2018, that will incorporate an orbiter, a robotic lander, and rover. Since it will conduct its exploratory work on the far side of the Moon, there will be a need for a communications satellite, that’s why the Queqiao lunar communications relay satellite was launched.

Notes

  1. In celestial mechanics, the Lagrangian points are positions in an orbital configuration of two large bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them. There are five such points, labeled L1 to L5, all in the orbital plane of the two large bodies. The first three are on the line connecting the two large bodies and the last two, L4 and L5, form an equilateral triangle with the two large bodies. The two latter points are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies. Several planets have minor planets near their L4 and L5 points (trojans) with respect to the Sun, with Jupiter in particular, having more than a million of these. Artificial satellites have been placed at L1 and L2 with respect to the Sun and Earth, and Earth and the Moon for various purposes, and the Lagrangian points have been proposed for a variety of future uses in space exploration.
Lagrange points in the Sun–Earth system
Lagrange points in the Sun-Earth system (not to scale).

Sources

  • “Chinese satellite snags new views of Earth from lunar orbit” on Planetary.org
  • “Amateurs used a Chinese satellite to photograph Earth and the moon” on New Scientist

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