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4M Lunar Flyby Spacecraft Amateur Radio Payload Now in Silent Earth Orbit

11/12/2014

[CORRECTED/UPDATED 2014-11-28 1940 UTC] The Amateur Radio payload in the Manfred Memorial Moon Mission (4M) lunar flyby experiment has gone silent, but the spacecraft itself will likely be in Earth orbit for some time to come.

“It is there for some thousands years, I think, but it might also be ejected in heliocentric orbit if it passes close to the Moon, which is what some simulations show,” said Ghislain Ruy, LX2RG, of Luxspace (LXS), the private company behind the 4M payload. Ruy said the 4M is orbiting Earth every 16.5 days.

Ruy told ARRL that the 4M’s Amateur Radio payload exhausted its batteries on November 10 after 438 hours of service — four times more than Luxspace engineers had predicted. “It can be considered a huge success that opened new paths and made people think or even dream,” he said.

On November 10 the battery voltage began dropping, and Rein Smit, W6SZ, in California, received the last signal at 0135 UT on November 11, when the battery voltage had fallen to 8.4 V.

“Here at Luxspace, we have to thank you all for the reports, for the tracking, and we also hope that we provided you with the challenges you expected,” Ruy posted to theMoon-Net list. “4M may possibly awaken from time to time if illumination becomes better. We shall now endeavor to prepare the next one.”

The Chinese Chang’e 5T-1 lunar mission payload that the 4M initially accompanied into space on a Long March 3C rocket already has been recovered. The 4M and Chang’e 5T-1 — part of the China Lunar Exploration Program — launched into space on October 23, with the 4M payload hitchhiking on the launch vehicle’s third stage.

Until early this week the Amateur Radio payload was transmitting a WSJT JT65B beacon and telemetry on 145.980 MHz, and it was only by chance that the 4M managed to attain Earth orbit on the return leg, rather than burn up in the atmosphere — which had been its more likely fate.

Ruy said Luxspace funded the 4M project entirely, which required it to be “cheap, fast, and efficient.” Several partner companies provided free or discount-price services. “I had only 6 months to set it all up, starting from a blank page,” he said, pointing out that 7 months ago he “knew nothing” of JT65B. Ruy said Luxspace used the project as an opportunity to help train the company’s younger, less-experienced engineers, and that 4M had been “quite an education.”

“The next mission will integrate all that was discovered and learned,” Ruy told ARRL, adding that he’d like very much to include a second, similar Amateur Radio payload on the next mission, “if volume and antenna accommodations allow.” The next Luxspace mission will not rely on Amateur Radio for telemetry, but would use the company’s own ITU-coordinated frequencies.

Attaching the 4M payload to the last stage of the Long March 3C rocket, Ruy said, “had a lot of drawbacks — some of them terrible,” but it kept down costs. Only the Chang’e 5T-1 was tracked, and not the last stage, so LXS engineers were only able to estimate the 4M’s lunar transfer orbit injection prior to launch. The 4M appeared to have an injection that was closer to that of Chang’e 5T-1’s than engineers’ estimates and, owing to small differences in orbital mechanics, Chang’e 5T-1 was able to re-enter Earth’s atmosphere, while 4M did not.

Ruy said that 4M was a hands-on experiment to get a practical grasp of the problem, and it turned out to be "a much bigger success than expected."



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