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NASA’s New Horizons spacecraft is currently located at 13 million miles from Pluto and it is expected to reach the remote dwarf planet July 14. But as the tiny spacecraft races toward the 1430-mile-wide planet and gets increasingly closer, NASA controllers have one final challenge – to detect the planet.
Mission navigators will need to position the probe so that it is able to perform its historic flyby on July 14, but that is easier said that done. NASA scientists explained that finding Pluto is by far one of the hardest tasks in space exploration. Moreover mission controllers will have to make some crucial decisions by July 4 which is the final deadline the spacecraft’s trajectory can be altered.
Because Pluto is so far away from the sun, it takes 248 terrestrial years to complete a revolution around it. So, finding Pluto is much a matter of guesswork. Additionally, due to the huge distance between Earth and New Horizons, there’s a delay of nine hours in sending and receiving signals which makes it really hard to control the craft in real time.
The piano-sized probe must reach one of Pluto’s poles at a 7,750 mile distance and it must quickly calibrate its instruments to analyze the surface below. NASA controllers said that that was only one shot. Unlike orbiters, if you miss a day of experiments you cannot say that you will resume it the next day, explained Bobby Williams, head of the mission’s navigation crew.
The maneuver must be precisely done even though NASA engineers do not have the exact coordinates of the planet, while the latter performs a complex dance through space under the influence of its largest moon Charon’s gravity.
After the tight flyby, New Horizons must settle on a steep orbit into the shadows of both space bodies, where it should be able to calmly analyze the atmosphere of the two worlds.
In order to guess the orbit, the spacecraft takes pictures of the planet on a daily basis. Mission controllers can use those pictures, taken by the probe’s Long Range Reconnaissance Imager instrument (LORI), to estimate Pluto’s position as related to background stars. But they cannot calculate how far the dwarf planet it.
“You can’t tell whether it’s small and close or big and far. It’s a really interesting problem that we’ve never had at any other planet,”
said Fran Bagenal from University of Colorado Boulder and mission’s co-investigator.
Mission navigators will be able to tell the exact distance of Pluto when New Horizons performs the historic flyby. But at that point the team won’t be able to adjust its course.
Image Source: David Reneke
