In a first-of-a kind for an interplanetary spacecraft, NASA’s Juno spacecraft in October was able to detect Amateur Radio signals transmitting “HI” in coordinated, very slow-speed CW. More than a thousand radio amateurs around the globe greeted Juno October 9 as it looped past Earth for a gravity-assisted boost on its way to Jupiter. Participants were invited to spread out across 10 meters to transmit “HI” in very slow speed CW (1/25 WPM), sending 30 second dits punctuated by 30 second spaces and 90 seconds between the two characters.

“The second ‘HI’ was detected clearly,” University of Iowa researcher and Waves Principal Engineer Don Kirchner, KD0L, told ARRL, noting that the distance to the spacecraft was about 37,500 kilometers (23,250 miles). “The signals were usually just at or above the noise level, although at closest approach the first three dits of the ‘H’ had significantly higher signal levels,” Kirchner continued. “A possible explanation is that for a short time we were inside the ionospheric waveguide and, as we increased in altitude, went back above it for the last dit.”

Shortly after that, Kirchner said, the spacecraft went into safe mode, so outbound data were lost.

The experiment involved 16 identical rounds or cycles and ran a bit longer than 2-1/2 hours all told (1800 to 2040 UTC). The object of the experiment was to see if Juno’s onboard “Waves” experiment would be able to detect the collaborative RF. Spreading out participants on a wide range of 10 meter frequencies was intended to improve the chance of the Waves instrument’s hearing the ham signals. The detector has a bandwidth of 1 MHz.

According to the University of Iowa, after the flyby the Juno team evaluated the Waves instrument data containing the messages. Kirchner noted that while previous space missions — Galileo on its way to Jupiter, and Cassini headed for Saturn — were able to detect shortwave radio transmissions during their Earth encounters, it was not possible to decode intelligent information using the data from those spacecraft.

“We believe this was the first intelligent information to be transmitted to a passing interplanetary space instrument, as simple as the message may seem,” said Bill Kurth, a University of Iowa Researcher and Lead Investigator for the Waves instrument. “This was a way to involve a large number of people — those not usually associated with Juno — in a small portion of the mission.”

Among stations participating were operators at the Virginia Tech Amateur Radio Club’s K4KDJ, who posted a video of their activity on YouTube.

Kurth said the activity raised awareness of the mission, adding that the University of Iowa already has heard from some who plan to follow Juno through its science mission at Jupiter.

On December 10 during the fall meeting of the American Geophysical Union in San Francisco, Kurth and Juno Principal Investigator Scott Bolton of the Southwest Research Institute of San Antonio took part in a news conference to discuss the science gathered during the Juno flyby as well as the success of the “Say HI to Juno” project.

Kirchner said the project originated when public outreach staff at NASA’s Jet Propulsion Laboratory in Pasadena, California, wanted to know if the UI receiver was able to pick up a voice message. Kurth and Kirchner came up with the idea that a slow Morse code message might work, and Kirchner enlisted the University of Iowa Amateur Radio Club to get involved, spreading the word via ham radio to raise awareness of the project.

Plans call for Juno to orbit Jupiter 33 times. Among a variety of investigations, Juno will explore Jupiter’s northern and southern lights by flying directly through the electrical current systems that generate them. NASA’s Jet Propulsion Laboratory, which manages the Juno mission for the principal investigator, posted a mini-documentary about the “Say HI to Juno” event on YouTube.

“We would again like to thank all amateurs who participated,” Kirchner told ARRL. “At last report about 1400 had sent in a request for a Juno QSL.” Anyone who took part can request a QSL card that acknowledges their help. -- Thanks to Don Kirchner, KD0L, and the University of Iowa