In a year brimming with ongoing discoveries about distant, unknown worlds, including the Solar System’s planets and a comet, 2015 seems to be shaping up to be the “Year of Pluto.” Less than two weeks before the New Horizons spacecraft will make a historic flyby of the dwarf planet and its moons, on June 29 (June 30 in New Zealand) NASA’s SOFIA (the Stratospheric Observatory for Infrared Astronomy) jetliner made observations of Pluto as it briefly passed between a star and the Earth. This event, known as an “occultation,” “back lit” the dwarf planet, making astronomical observations easier. In addition, data collected during these observations will further aid the New Horizons team, as their spacecraft approaches closer and closer to Pluto and its moons by the day.
According to NASA, the occultation allowed Pluto’s shadow to move across the face of the Earth at a breakneck speed of 53,000 mph; in order for this phenomenon to be observed, “instruments and observers” had to be “in the right place at the right time.” Luckily, after some last-minute corrections, SOFIA was precisely in position to make these rare observations. The modified Boeing 747SP jetliner is equipped with a telescope 100 inches in diameter, which was built by DLR, the German Aerospace Agency. In addition, SOFIA is currently operating in the Southern Hemisphere (out of Christchurch, New Zealand) and will continue to through July 24. NASA stated that SOFIA is scheduled to make 15 program flights, covering 40 separate observations. SOFIA previously observed a Pluto occultation four years ago, in July 2011.
Those working with SOFIA and its flight programs were enthusiastic about its recent observations and how these will aid the New Horizons team as they prepare for an interplanetary first. Pamela Marcum, SOFIA Program Scientist at NASA’s Ames Research Center, stated: “SOFIA observations of Pluto demonstrate a capability to make detailed measurements of Pluto’s atmospheric density and structure. … This flight adds to our understanding of how the atmosphere of Pluto evolves over multiple-year time scales as its elongated orbit takes it farther away from the Sun.
“New Horizons will give us comprehensive ‘snapshot’ measurements of Pluto for which ongoing occultation studies provide context. This unique opportunity to connect what SOFIA observes remotely with in-situ measurements from New Horizons will allow future analyses of Pluto from Earth by SOFIA and other observatories to be considerably enhanced.”
Marcum’s words were echoed by Ted Dunham of Lowell Observatory, located in Flagstaff, Ariz., who was the principal investigator for this phenomenon. He related: “This observation was a collaboration between researchers at NASA, the Lowell Observatory’s Discovery Channel Telescope, and the Massachusetts Institute of Technology. I’m happy to say the mission was hugely successful; we were right where we wanted to be, and, after preliminary examination, the data quality appears excellent.”
An article by Nadia Drake from the National Geographic website also touched on the brief but exciting encounter with a distant world from an altitude of 39,000 feet, where cloud cover isn’t a problem: “Yet off we zoomed through the night, zigzagging over the ocean for about six hours as teams calibrated their instruments and got preliminary data on both Pluto and the star.
“Then, for about 90 seconds in the early winter morning, we watched as Pluto dimmed the face of that distant star. A brief flash of brightness toward the midpoint of Pluto’s passage revealed that SOFIA had hit its target bang on and provided astronomers with a beautifully precise set of data.”
It is hoped these occultation observations, along with data provided by New Horizons, will give researchers more than a taste of what the atmospheric conditions are like on Pluto. While the data from SOFIA will be made immediately available to the New Horizons team, it will be made available to the public in July 2016 through the program’s scientific data archive.
New Horizons is on course to make its encounter with Pluto in less than two weeks. According to a previously published AmericaSpace article by Leonidas Papadopoulos, the spacecraft made its final, 23-second course correction burn on June 29 to narrow its trajectory. Recent long-range observations of Pluto and its moon, Charon, have revealed unexpected, surprising details about the system; Pluto seems to have a large crater-like formation on its surface and appears irregular in shape, while Charon has an “enigmatic” dark area on its northern pole.
Papadopoulos wrote: “More of these fascinating observations are nearly upon us, and it’s only a matter of a few more weeks before speculation and theory will be replaced by hard facts and high-definition images. Up till now, New Horizons, which is currently at a distance of 16 million km from Pluto and closing in fast, remains in perfect health, ready to open the gates of the Solar System’s planetary underworld for all to see.” A more recent update by Mike Killian stated that at present time, New Horizons is “go” for its original best flight path to Pluto, meaning that the way is clear for the spacecraft to transit as originally planned to obtain its scientific results.
The spacecraft will pass within 13,000 km above Pluto’s surface during the evening of July 14, undoubtedly thrilling scientists and casual observers alike.
Video Credit: NASA Armstrong Flight Research Center on YouTube
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