Pluto Eve: Anniversaries and Milestones

As noted many times in this blog, August 24 is the day that will live in infamy, the day in 2006 when four percent of the IAU violated their group’s own bylaws and voted for the controversial resolution that demoted Pluto and established a very flawed definition of the term planet.

But this year, also known as Pluto Eve, this date is much more than the anniversary of a poor decision that never really stuck.

This year, August 24 and the next day, August 25, are a celebration of milestones past, present, and future.

Twenty-five years ago, on August 25, 1989, the Voyager 2 spacecraft made its closest approach to Neptune, sending back beautiful images of the blue planet and its largest moon, Triton, that excited people around the world.

Distant Neptune had never before been seen up close, and little was known about it before the completion of the Voyagers’ Grand Tour of the solar system’s gas giants.

I remember being entranced by Neptune’s vivid blue color, so much so that I actually felt compelled to paint the planet in watercolors surrounded by the black background of space. I collected every Neptune image I could find from the flyby and still have most of them.

The Neptune flyby revealed more than just the blue planet and its surface features. Images of Triton showed it to have a thin atmosphere, some volcanic activity, some craters, and a crust of frozen nitrogen on top of an icy mantle likely covering a core of metal and rock.

With a diameter of 1,680 miles, Triton is bigger than Pluto, which has an equatorial diameter of 1,430 miles. Because it orbits Neptune in the direction opposite the giant planet’s rotation, Triton is believed to have once been a planet that orbited the Sun on its own only to be subsequently captured by Neptune, becoming its largest moon.

Like Pluto, Triton likely originated in the Kuiper Belt, which is why it is viewed by many scientists as an analogue for Pluto. At the Pluto Science Conference last year, images of Triton were discussed and presented because these two objects are believed to be very similar.

Both are geologically active, slightly smaller than Earth's moon, possess thin, nitrogen-dominated atmospheres and have various ices (of carbon monoxide, carbon dioxide, methane and nitrogen) on their surfaces, as noted by Dr. Paul Schenk of the Lunar and Planetary Institute in Houston, Texas.

The excitement over the first ever images of Pluto New Horizons will deliver in less than one year in many ways parallels the reaction many had to the first views of Neptune and Triton in 1989.

In an unusual coincidence, August 25, 2014 is an important milestone linking the Voyager 2 and New Horizons missions. On this day, New Horizons will cross the orbit of Neptune, putting the spacecraft in what team members call “Pluto space.”

This milestone is the final planetary orbit crossing for the vehicle launched on January 19, 2006 and crossed the orbit of Uranus on March 18, 2011.

To commemorate both the Neptune flyby anniversary and New Horizons’ latest milestone, Schenk used footage from the 1989 Triton flyby and restored the photos to create a new, higher resolution map of Triton that has been made into a video.

That video can be viewed at https://www.youtube.com/watch?v=QDCndVGowmc#t=59 . Schenk discusses this work on his blog at http://stereomoons.blogspot.com/ .

This new, enhanced view of Triton is an enticing preview of what we may find at Pluto in less than one year.

To commemorate these occasions, NASA TV will air a program on Monday, August 25 from 1-3 PM EDT live from Washington, D.C. at http://www.nasa.gov/nasatv .

The schedule is as follows:

• The 1-2 p.m. event will feature a panel discussion with:
Jim Green, director, NASA’s Planetary Division, Science Mission Directorate, NASA Headquarters, Washington
Ed Stone, Voyager project scientist, California Institute of Technology, Pasadena
Alan Stern, New Horizons principal investigator, Southwest Research Institute, Boulder, Colorado

• The 2-3 p.m. event will include several New Horizons science team members giving personal accounts of their work during the Voyager Neptune encounter and their new assignments on the Pluto mission. Panel participants include:

Moderator: David Grinspoon, Planetary Science Institute, Tucson, Arizona
Fran Bagenal, University of Colorado, Boulder
Bonnie Buratti, NASA Jet Propulsion Laboratory, Pasadena, California
Jeffrey Moore, NASA Ames Research Center, Moffett Field, California
John Spencer, Southwest Research Institute, Boulder, Colorado

Media can ask questions from participating NASA locations, or by telephone. To participate by phone, reporters must contact Steve Cole at 202-358-0918 or stephen.e.cole@nasa.gov and provide their media affiliation by noon Monday.

I will be phoning in and hopefully get to ask at least one question, then following up with an article about the event at The Spaceflight Insider, at http://www.spaceflightinsider.com/ .

Media and the public can also ask questions during the event via social media using the hashtag #askNASA.

What has come as a genuine surprise is the sheer amount of attention Pluto and the New Horizons mission have been getting an entire year prior to the flyby. I did not expect this much attention and activity centered on Pluto before 2015 began. The fact that there has been this much excitement starting more than a year in advance is more than encouraging.

And it shows just how wrong those who dismiss the ongoing debate over Pluto’s status are.

As has been pointed out many times, New Horizons launched seven months before the 2006 IAU General Assembly. Given the knowledge that a probe was already on its way to Pluto, why wouldn’t the organization wait until the images and data come in before making a decision? In science, the conclusion is drawn as a result of the experiment, not before the experiment takes place.

This mistake will continue to haunt the IAU and its decision no matter how much the group’s leadership digs in its heels and refuses to reopen the discussion. The images and data produced by New Horizons, which will continue to come in through the end of 2016, will by far eclipse a decade-old decision that becomes more and more irrelevant with every new discovery.

This is the last August 24 when we will not have close-up images of Pluto. Next August 24, we will have the most clear idea yet of just how alive a planet one astronomer prematurely wrote off as dead is.