Playback from Pluto

By Janet McMillan, C2ST volunteer and graduate student in chemistry at Northwestern University

Ten years to the night that the New Horizon Mission to Pluto was launched, William S. Higgins, an ambassador for NASA’s Solar System Ambassador Program, shared the wonders of the ground breaking discoveries and mysteries that remain to be uncovered about the dwarf planet and its surrounding objects.

The New Horizon’s space probe reached Pluto last July–a moment that has been over three decades in the making. Scientists had petitioned for the funding for four other missions before their proposal to send New Horizon to Pluto was accepted and planning of the mission could begin.  Since the space probe was finally launched in 2006, it had been travelling first through the inner solar system, maneuvering using its reserve of fuel, then used Jupiter’s gravitational field as a sling shot to propel itself still further, finally reaching Pluto in July of 2015.  Since its encounter, New Horizon has been transferring data across billion miles, at a rate of about 2000 bits per second–about 3,000 times slower than a typical internet connection today.  The space probe has been sending pictures, but also making measurements with its infrared, ultraviolet and particle spectrometer, with each measurement lending a valuable piece in understanding how Pluto came to be and what it is like now.

Higgins–who volunteers for NASA when he is not doing his day job as a radiation safety physicist at Fermi National Accelerator Laboratory–was lucky enough to be in the room with mission scientists when the encounter took place.  Showing the audience a picture from the first moments after data from Pluto had been received, Higgins described the intensity and joy of the moment.  The overwhelming thrill experienced by each and every person involved was obvious.  The sheer immensity of the man hours, the number of calculations and engineering decisions that converged to enable a single flyby lasting only hours was striking.

Up until recently, the best pictures of Pluto showed little detail of the planet.  Higgins painted a powerful picture of the weeks New Horizon approached Pluto. Since May of 2015, the probe passed the range where its photos of the planet were as sharp as those taken with the Hubble space telescope.  Almost every day, mission scientists would receive new pictures–the best that had ever existed of the body, only to receive an even better picture the next day.

What has become the most iconic picture from the Horizon mission–a heart shaped formation on the side of planet, scientists have learned, is a lake of solid nitrogen, similar to a glacier that is most likely actively flowing on the surface of Pluto.  Despite this breakthrough, astrochemists are only at the beginning of understanding the chemistry of Pluto, its atmosphere and surrounding bodies, however for the first time ever, we can begin to learn about these things.

The spacecraft is expected to function for another 15 years, during which it will conduct a number of close flybys with other objects in the Kuiper belt, with the next fly by expected to occur in 2019 with a Kuiper belt object an estimated 45 kilometers in diameter.  Those fascinated by Pluto still have much to look forward to in the way of new discoveries–even once the data transmission from the Pluto flyby is completed in the coming months, it will take years for scientists to analyze the data and piece together the story it tells of the beloved former ninth planet.  In Higgins words–stay tuned.

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