Celebrating Juno’s Arrival at Jupiter this Weekend

Fig. 1

Engineers and scientists at NASA will be spending some tense time at NASA’s mission control as the four-ton spacecraft Juno ends its five-year, 1.74 billion-mile journey to Jupiter, the solar system’s largest planet. It will swoop in on Jupiter at 150,000 mph, making it one of the fastest man-made objects ever, and begin circling the gas giant for 107 days as it settles into its final orbital. It will stay in its orbit for about 20 months, circling the planet every 14 days and coming to within 2,600 miles of the planet’s cloud tops.

Juno is scheduled to “arrive” at Jupiter on the evening of July 4th, and I’m hoping some of the networks cover it like they once covered Gemini and Apollo missions. After all, NASA even put a video camera on the Juno, and one of its main missions is public relations, sending back never-before-seen images of Jupiter.

Here’s some Juno trivia to get you psyched up for this weekend’s Jovian fireworks:

Who’s onboard? Nobody alive, that’s for sure—at least not human. But the spacecraft has been carrying three Lego figurines crafted out of space-grade aluminum to represent the Roman god Jupiter (Zeus to the Greeks), his wife Juno, and the Italian scientist Galileo Galilei (who made several discoveries about Jupiter, including four of its moons). Galileo is depicted with a telescope, the tool he used to make his astronomical discoveries. Jupiter holds his customary lightning bolts, while Juno has a magnifying glass (signifying the goddess’ search for truth).

Fig. 2
Galileo also rates an aluminum plaque. It measures about 3 x 2 inches and carries his self-portrait, plus a description (in his own handwriting) of his observations of Jupiter from 1610.

Fig. 3
Similar Lego figures have traveled on the space shuttle, the International Space Station, and to Mars.

Keeping Jupiter and its neighbors clean: Scientists know that microbes and other living organism can exist in some pretty harsh conditions, from boiling seawater around deep-sea vents to outer space. They also know it’s possible that some Earth bugs climbed aboard Juno prior to take-off. To prevent possible stowaways from infecting Jupiter—or, more likely, one of its moons such as Callisto or Ganymede—Juno will spend the last 5.5 days of its life maneuvering to crash into Jupiter’s atmosphere to burn up. That should happen around the end of February 2018.

Fig. 4
Solar power at a distance: Juno is the first NASA spacecraft to travel so far from Earth on solar power. All the other probes have carried relatively small nuclear reactors. So Juno has three solar arrays, each measuring about 29 ft long and 9 ft wide, for a total of nearly 790 ft2. They contain 18,698 individual gallium-arsenide solar cells, enough to generate 14 kW if Juno were orbiting Earth. But when it’s flying around Jupiter, the distance to the sun is so great that power from the arrays drops to 500 W.

The distance between the Earth and Jupiter will also slow down communications between NASA and its spacecraft. Radio transmissions travelling at the speed of light will take at least 48 minutes to make the trip from Juno to NASA.

Good luck, NASA. I’ll be watching.

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Discuss this Blog Entry 4

on Jul 5, 2016

"thee Lego figurines"? You should check better the article before submitting it. Besides that, it is a very exciting article.

on Jul 6, 2016

Good catch.

on Jul 5, 2016

The typo's been fixed. Thanks for the heads up!

on Jul 26, 2016

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What's A Skeptical Engineer?

A questioning, sometimes humorous look at technologies, engineering, and the world.


Stephen Mraz

Steve serves as Senior Editor of Machine Design.  He has 23 years of service and has a B.S. Biomedical Engineering from CWRU. Steve was a E-2C Hawkeye Naval Flight Officer in the U.S. Navy. He...
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