NASA Juno Jupiter Probe Reaches Halfway Point -- Science Mission Set For Test Run

Today -- July 31 -- NASA's Juno Jupiter probe will reach the farther point in its orbit of the giant gas planet. As it swings back towards Jupiter, the spacecraft's instrumentation will begin to send back historic data that should prove to revolutionize our understanding of the solar system and beyond.

According to a media release, at 3:41 Eastern Daylight Time (EDT) or 19:41 GMT, NASA's Juno spacecraft will be about 5 million miles or 8.1 million kilometers from Jupiter. The farthest point of Juno's orbit is known as the "apojove." At that point, Jupiter's strong gravitational field will begin to pull it back towards the planet and the eagerly awaited data will begin its transmission. On August 27, Juno will finish its first orbit of the giant gas planet, finishing 2,600 miles or 4,200 kilometers from the tops of its cloud cover, which will be its closest encounter with Jupiter.

NASA's Juno Mission

So far, NASA's Juno spacecraft has a flawless record. As it approached Jupiter on July 4, it executed a 35-minute maneuver which allowed Jupiter's gravitational field to capture the spacecraft into orbit. Because of the complex nature of the maneuvers required to settle Juno into orbit, NASA scientists initially turned its science instrumentation off.
Beginning with the August 27 pass back towards Jupiter, the instrumentation will be reactivated so that it can record and collect data in a sort of trial run prior to the science mission itself. The Juno mission will see the spacecraft performing two initial looping orbits of Jupiter, each taking just over 53 days. After those maneuvers, known as "capture orbits," Juno will fire its engines to shorten its orbit to 14 days in order to begin its science mission. That should happen in November.

As reported in Space Magazine, Juno's science mission will consist of another 30 loops around Jupiter in full observational mode. The Juno mission is scheduled to end in February 2018 as the spacecraft deliberately plunges directly into Jupiter's turbulent atmosphere, where high temperatures, a super strong magnetic field and other forces will eventually results in its destruction.

The Science Behind The Juno Jupiter Mission

A piece in EE Times explains how NASA scientists created a low power system for the Juno mission. Grappling with a shortage of plutonium, which has generated electricity for previous space missions, NASA developed a photovoltaic -- or solar powered -- system.

So, how does a solar power system operate 365 million miles or 588 million kilometers away from the sun?

Juno is outfitted with about 19,000 photovoltaic cells, which will produce about 400 watts of electricity. It doesn't sound like much, but Juno is also equipped with super energy efficient instrumentation and computer systems. The solar panels are placed on the three arms that radiate from the Juno spacecraft, each of them 30 feet or 9 meters long. At that distance, Juno's solar panels only receive 3.4 to 4.1 percent of the solar intensity that would be registered on earth. In comparison, here on earth, the same set of solar panels would produce 14 kilowatts of electricity.

In probing Jupiter, NASA scientists hope to glean clues about the formation and evolution of our solar system. As noted in a Forbes Magazine article, the knowledge gained from the $1.13 billion USD Juno mission will also allow NASA to better understand the many other gas giant planets that have been discovered well outside our solar system. One of the most interesting finds of the last decade has been so-called "hot Jupiters," or exoplanets with similar gaseous structures to Jupiter but which orbit their own suns much more closely, with a much higher atmospheric temperature.

Juno's data on Jupiter's deep atmosphere, mass, and magnetic fields, not to mention the close up images that will be sent back to earth, will represent a huge leap forward for NASA and other organizations in the understanding of planetary science.

[Image via NASA/JPL-Caltech]