(Image: NASA/JHUAPL/SWRI)
NASA鈥檚 New Horizons spacecraft is less than a day from its close fly-by of Pluto, but that鈥檚 not stopping the results from flying in.
鈥淭he science is already mouth-watering,鈥� said Alan Stern, who leads the mission, speaking at a press conference earlier today from mission control at the Johns Hopkins University Applied Physics Laboratory.
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New Horizons has now confirmed that Pluto鈥檚 radius is 1185聽kilometres, plus or minus 10聽kilometres, making it the largest object in the Kuiper belt, the zone on the edge of the solar system. That puts to rest a question first raised with the discovery of Eris, another large Kuiper belt object whose discovery in 2005 was partly responsible for Pluto鈥檚 downgrade from planet to dwarf planet status a year later.
This new radius will help us figure out how Pluto and its largest moon, Charon, formed, and provide a clearer picture of Pluto鈥檚 atmosphere.
In fact, New Horizons already has a new bead on Pluto鈥檚 atmosphere. The probe detected ionised nitrogen streaming off the dwarf planet five days before closest approach. That surprised the team, because the probe wasn鈥檛 expected to pick up such traces until 24 to 36 hours out.
Further study will determine whether the nitrogen levels are stronger than predicted, or if there is another reason for the early signal.
Finally, the team has confirmed that hints of an ice cap at Pluto鈥檚 pole weren鈥檛 just in their imagination: spectroscopy measurements show it really is ice. Now they are looking for signs of a similar ice cap on Charon.
There will be a whole lot more to come in the next few days. New Horizons is set to make its fly-by at 12:49 BST tomorrow, and the team is brimming with anticipation.
鈥淚t鈥檚 been something that鈥檚 been in our future for so long,鈥� said Stern. 鈥淚t feels like you鈥檝e been walking on an escalator for almost a decade, and then you step on a supersonic transport. That鈥檚 the pace of the fly-by.鈥�
For the latest updates on New Horizons and all the breaking news from Pluto, follow our live blog.
