NASA’s Juno Mission Originally Set to Demonstrate Kepler’s Laws

In an article I read on entitled, Juno Jupiter Probe Won’t Move into Shorter Orbit After All, author Mike Wall follows up on the progress of the Juno spacecraft that was set in orbit on July 4, 2016.  The Juno spacecraft’s current orbit around the planet Jupiter is approximately 53 days.  The spacecraft was scheduled to be moved closer to the planet so much so that the orbital period would be reduced to 14 days.  But, according to the NASA agency officials, Juno will not move closer to Jupiter as they had originally planned in their mission.

According to the author, the spacecraft is in a highly elliptical orbit and was scheduled to perform an engine burn to bring the spacecraft closer to Jupiter.  A problem occurred and caused the mission plans to be held off.  As of February 2017, the mission plans for the Juno spacecraft have now been canceled.  The author quotes one of the Juno project managers and informs the reader that there was a concern that the main engine burn would affect the mission objectives.  According to the author, the mission was launched as a way to study the magnetic and gravitational fields, composition, and interior structure of Jupiter through close flybys.  The close flight brought the spacecraft within 2,600 miles of the planet.

The author continues by informing the reader that the Juno mission was set to reduce its orbit time to accomplish more flybys.  The 14 day orbit that NASA desired for the mission would have called for the spacecraft to follow through with 30 flybys to take footage of the planet Jupiter.  The 53-day orbit would only complete about 12 flybys.

The author closes the article by telling the reader of the new found advantages of a longer orbit as mentioned by the Juno mission team.  Since the shorter orbit won’t take place, the mission team has realized that they can do more observations from the outer portions of Jupiter’s magnetosphere.  They have also found that the longer orbits allow for protection of the spacecraft from radiation.

Reading this article reminded me of the lecture tutorial we worked on regarding Kepler’s Second Law.  In part three of the lecture tutorial, we talked about orbit eccentricities.  We talked about how certain planets or objects in our solar system travel in different eccentricities of orbit.  The higher the eccentricity of orbit the more elliptical the orbit will be.  There was not a measurement listed in the article, but my guess is that the orbit eccentricity was above a measurement of 0.90 because the article mentioned that the Juno spacecraft orbit was highly elliptical.  The Juno spacecraft also had to be pretty near to the planet Jupiter because its orbital period was only 53 days.

In the lecture tutorial we worked on regarding Kepler’s Third Law, we utilized two different graphs that showed planet mass, orbital period, and orbital distance in astronomical units.  In the graph, the planet that had the shortest orbital period was closet to the Sun.  Mercury had an orbital period that we can use to compare to that of the Juno spacecraft.  Since Mercury’s orbital period in years is approximately 0.24 years or about 87 days, the Juno spacecraft had to have been closer to Jupiter than Mercury is to the Sun.  This would explain the shorter orbit.  With Mercury being so close to the Sun, it experiences large amounts of radiation.  This very well might be the reason why the mission team for the Juno spacecraft was very concerned about the effects of the spacecraft moving in too close to the planet Jupiter.

Kepler’s laws apply to the spacecraft just like they do to other objects in our solar system.  Most objects in the solar system orbit their central object or star in an ellipse with their central star being their main focus.  The Juno mission tried to move the spacecraft closer to its central star, Jupiter, but it ran the risk of destroying the projects goals.  But, the project managers understood that moving Juno closer to the planet by way of an engine burn would reduce the orbit time frame which is what Kepler’s second law sums up.  An object or planet in our solar system moves faster in its orbit when it is nearest to its central star and slowest when it is the furthest away from it.  But, in the process of its orbit, the object or planet always sweeps out equal amounts of area in equal amounts of time.  Kepler’s third law ties into the orbital time frame for the spacecraft.  The time it took Juno to orbit Jupiter is directly related to the distance the spacecraft was from the planet.

It is much easier to spot Kepler’s laws at work in planetary motion in articles because the laws have been proven to work time and time again.  I hoped that the article would go into grater detail about why the Juno mission was canceled.  It seemed to be a little vague.  But, I was able to look up articles like, NASA Concerned That Juno Spacecraft Might Crash Into Europa, in the Huffington Post that filled me in where this article did not.  The article wasn’t a typical explanation of Kepler’s laws.  The reader really had to pay attention to the mission goals to see Kepler’s laws at work, but overall, his laws still applied.





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