NASA's Plan To Shorten Juno's Orbital Period Around Jupiter Put On Hold

Although maybe lost a bit in the recent excitement of a future expedition to Mars, there is still plenty of interesting news across the asteroid belt, especially when it comes to Jupiter and the Juno probe. Juno, launched on August 5, 2011, finally reached its destination this past summer, arriving in Jupiter's orbit on the Fourth of July.

According to Samantha Mathewson of, Juno traveled 1.7 billion miles before finally reaching Jupiter. In late August, Juno completed its first orbit of Jupiter.

However, NASA has now announced that an "engine burn," which was originally scheduled for October 19 and would have significantly shortened Juno's orbital period, has been postponed. According to NASA, the burn is called the "period reduction maneuver," or PRM, and it was intended to shrink Juno's orbital period around the planet from 53.4 days all the way down to 14 days.

It is the last scheduled burn of its kind. The reason for the delay was to do more research on a crucial pair of valves, says NASA.

"Telemetry indicates that two helium check valves that play an important role in the firing of the spacecraft's main engine did not operate as expected during a command sequence that was initiated yesterday," Rick Nybakken, Juno project manager at NASA's Jet Propulsion Laboratory, said in the press release. "The valves should have opened in a few seconds, but it took several minutes. We need to better understand this issue before moving forward with a burn of the main engine."

The burn has now been scheduled for December this year. NASA explains that the ideal time for such a maneuver is when the spacecraft is closest to Jupiter. The next chance for this will be on December 11.

The fifth world from the sun and first of the gas giants, Jupiter is a fascinating place for a variety of reasons. Jupiter is the largest planet in the solar system, and perhaps its most distinguishing feature is a massive red spot, which is a storm that has been swirling for maybe hundreds of years.

Jupiter is also home to nearly 70 known moons. One of Jupiter's moons, Europa, one the Galilean moons (Jupiter's four largest satellites), is believed to contain a massive subsurface ocean. Europa clearly can capture one's interest, and it has recently been in the news as well, with reports of possible water plumes erupting from its surface.

There is still plenty of information left to be gathered about Jupiter. One of the elements that makes Juno so significant is the fact that it is the first spacecraft sent to perform a "long-term mission" around Jupiter since the Galileo probe, according to It may be the best opportunity to learn about Jupiter in quite a while, and NASA has stated how the goal of Juno is to better understand the genesis of the planet as well as the entire solar system.

Galileo, which was launched in 1989 and ended in 2003, was a big success, producing many facts on Jupiter and its moons. However, the mission still left many of Jupiter's mysteries unanswered, as Amy Shira Teital of Popular Science points out.

"The Galileo mission left us needing to know more about Jupiter, but NASA set its sights elsewhere and we were left with flyby missions. The Ulysses, Cassini, and New Horizons spacecraft all gathered data about Jupiter during flybys that sent them on trajectories to their primary targets of the Sun, Saturn, and Pluto respectively. But the next phase of Jupiter research wasn't far behind," Teital's article reads.

In NASA's press release, Scott Bolton, the principal investigator of Juno, explains that the greater orbital period will not affect the "quality of the science" that is collected while the spacecraft performs its flybys and studies Jupiter. According to Eric Berger of Ars Technica, NASA's goal was to have Juno make 36 orbits around Jupiter over the next 20 months. However, Berger explains that if the issue cannot be fixed, it may not be able to perform as many flybys, with the radiation of Jupiter being a factor as well.

The Juno mission has been reported to have cost $1.1 billion.

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