New Horizons' historic nine-year journey to Pluto is providing NASA scientists with all sorts of new intelligence about the dwarf planet's surface and its atmosphere, but the data we're receiving from the probe are providing almost as many questions as answers.
New information released by NASA suggests New Horizons' flyby of Pluto may have occurred at a startling transformational point in the dwarf planet's history. Sharply decreased atmospheric pressure readings recorded by the probe suggest that Pluto's atmosphere may be changing just as we've had the chance to observe it.
In the first ever pressure measurement recorded for Pluto's surface, radio signals beamed from two dishes in NASA's Deep Space Network were timed to coincide with the moment when New Horizons passed behind the dwarf planet, approximately one hour after the flyby. The radio waves travelled through Pluto's atmosphere before being received by New Horizons, and the way the signals were bent by Pluto's atmospheric gases contained some surprises for NASA scientists.
Specifically, the gas pressure at Pluto's surface is 7 microbars, about half of what previous estimates predicted it would be (and only 1/100-thousandth that of the pressure we feel on Earth). NASA scientists say this could mean as much as half of Pluto's atmosphere has frozen and descended onto the dwarf planet's surface, and that further declines in atmospheric stability could be set to occur.
"For the first time we have ground truth, measuring the surface pressure at Pluto, giving us an invaluable perspective on conditions at the surface of the planet," said New Horizons researcher Ivan Linscott of Stanford University in a statement. "This crucial measurement may be telling us that Pluto is undergoing long-anticipated global change."
We'll know more soon hopefully, with New Horizons set to transmit further atmospheric readings in the coming weeks.