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| A Hubble image shows Pluto, its largest moon Charon, and two smaller moons. This is the current best resolution we can see of Pluto, a view that New Horizons will greatly surpass. - NASA |
One year from today, everybody’s favorite dwarf planet will receive its first man-made visitor. The New Horizons mission, which launched in 2006, will make its closest flyby of Pluto on July 14, 2015.
Right now, Pluto is mainly known as that object in the solar system that used to be a planet (some would argue it was never a planet, simply misclassified as one for a long time). Scientists have been studying the small body since its discovery in 1930 and know a fair amount about its basic properties. But once New Horizons sweeps past and observes Pluto with its collection of high-tech instruments, there will be an explosion of new knowledge about the tiny world.
So what is the current state of Pluto science and how might things look different in one year?
Pluto is located far beyond all the outer planets, roughly 4.5 billion miles from Earth. Out there, sunlight is about 1,000 times fainter than on our own planet, and Pluto’s surface temperature is a chilly -380 degrees Fahrenheit. Like Uranus, Pluto rotates on its axis like a knocked over top, so that its north pole is at about the same place that other planets’ equators are. No one is sure exactly why this is, but some scientists suspect a major impact by a large space rock billions of years ago could have tipped the dwarf planet over.
Pluto has a radius of 733 miles, making it roughly two-thirds the size of our moon. It is the second-largest known object in the Kuiper belt, a collection of small frozen bodies beyond the orbit of Neptune. Its surface is almost entirely nitrogen ice and it has an extremely thin atmosphere of nitrogen, methane, and carbon dioxide. This faint envelope of gas has a pressure more than 10,000 times less than surface pressure on Earth.
Starting in January 2015, New Horizons will be passing what Stern calls the BTH (better than Hubble) line. The spacecraft will start returning images of the frozen dwarf planet that look better than anything we’ve ever seen before. This is when Stern suspects researchers might start getting surprises about the dwarf planet. Craters and mountains are some of the first things New Horizons could see, though it may also discover new moons.
Just prior to its Pluto encounter, New Horizons will be watching the dwarf planet rotate on its axis, spinning around every 6.4 Earth days. This will allow it to map most of the surface at high enough resolution to pick out features approximately 25 miles across, or roughly what you could see on the moon’s surface with a good pair of binoculars. The probe might see large impact craters or a network of geological fractures supporting the hypothesis that a large object hit Pluto in the past.
As the spacecraft swoops down over the surface at its closest approach, it will map one side of the planet down to a resolution of about 1,000 feet, with the best imagery reaching down to 230 feet. In image of New York City at 230-foot resolution, you’d be able to see streets, wharfs, buildings, and even count the ponds in Central Park. The motion of the probe as it passes over the surface will allow scientists to see features from slightly different angles, giving them the ability to create stereo 3-D images and infer heights.
The point of closest encounter is planned to take New Horizons over
an area of Pluto with the widest variety of different features. Because
of the regularity of orbital mechanics, the science team was able to
choose this precise location extremely far in advance of arrival,
maximizing their chance of seeing something interesting. As it flies
over the dwarf planet, the probe will also take the temperature of the
surface, sample the composition of Pluto’s atmosphere, and bounce radio
waves off its surface, which will tell researchers about underground
features.
New Horizon’s Pluto visit will transform the science of this small body in a matter of weeks, and it will likely take a long time before all of the data it provides will be unpacked. The only thing that would truly surprise the science team at this point would be if they find no surprises on Pluto, said Stern. It’s a safe bet to assume the probe probably won’t be definitively answering scientific questions so much as raising interesting new problems and providing researchers with many decades of mysteries.
As it leaves the Pluto system, New Horizons will burn its rockets and head toward a new destination. The team plans to send it to another Kuiper belt object, though exactly which one has not yet been decided. Hubble is right now searching for candidates, giving the mission a whole new world to observe and learn from.
Right now, Pluto is mainly known as that object in the solar system that used to be a planet (some would argue it was never a planet, simply misclassified as one for a long time). Scientists have been studying the small body since its discovery in 1930 and know a fair amount about its basic properties. But once New Horizons sweeps past and observes Pluto with its collection of high-tech instruments, there will be an explosion of new knowledge about the tiny world.
So what is the current state of Pluto science and how might things look different in one year?
Pluto is located far beyond all the outer planets, roughly 4.5 billion miles from Earth. Out there, sunlight is about 1,000 times fainter than on our own planet, and Pluto’s surface temperature is a chilly -380 degrees Fahrenheit. Like Uranus, Pluto rotates on its axis like a knocked over top, so that its north pole is at about the same place that other planets’ equators are. No one is sure exactly why this is, but some scientists suspect a major impact by a large space rock billions of years ago could have tipped the dwarf planet over.
Pluto has a radius of 733 miles, making it roughly two-thirds the size of our moon. It is the second-largest known object in the Kuiper belt, a collection of small frozen bodies beyond the orbit of Neptune. Its surface is almost entirely nitrogen ice and it has an extremely thin atmosphere of nitrogen, methane, and carbon dioxide. This faint envelope of gas has a pressure more than 10,000 times less than surface pressure on Earth.
Starting in January 2015, New Horizons will be passing what Stern calls the BTH (better than Hubble) line. The spacecraft will start returning images of the frozen dwarf planet that look better than anything we’ve ever seen before. This is when Stern suspects researchers might start getting surprises about the dwarf planet. Craters and mountains are some of the first things New Horizons could see, though it may also discover new moons.
Just prior to its Pluto encounter, New Horizons will be watching the dwarf planet rotate on its axis, spinning around every 6.4 Earth days. This will allow it to map most of the surface at high enough resolution to pick out features approximately 25 miles across, or roughly what you could see on the moon’s surface with a good pair of binoculars. The probe might see large impact craters or a network of geological fractures supporting the hypothesis that a large object hit Pluto in the past.
As the spacecraft swoops down over the surface at its closest approach, it will map one side of the planet down to a resolution of about 1,000 feet, with the best imagery reaching down to 230 feet. In image of New York City at 230-foot resolution, you’d be able to see streets, wharfs, buildings, and even count the ponds in Central Park. The motion of the probe as it passes over the surface will allow scientists to see features from slightly different angles, giving them the ability to create stereo 3-D images and infer heights.
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| A map of Pluto’s surface, showing brighter and darker areas. NASA |
New Horizon’s Pluto visit will transform the science of this small body in a matter of weeks, and it will likely take a long time before all of the data it provides will be unpacked. The only thing that would truly surprise the science team at this point would be if they find no surprises on Pluto, said Stern. It’s a safe bet to assume the probe probably won’t be definitively answering scientific questions so much as raising interesting new problems and providing researchers with many decades of mysteries.
As it leaves the Pluto system, New Horizons will burn its rockets and head toward a new destination. The team plans to send it to another Kuiper belt object, though exactly which one has not yet been decided. Hubble is right now searching for candidates, giving the mission a whole new world to observe and learn from.
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