Scientists Plan Pluto Flyby

BBC ^ | 2-26-2002 | David Whitehouse

[blam]

Tuesday, 26 February, 2002, 15:05 GMT

Scientists plan Pluto flyby

Golden opportunity to study Pluto

By Dr David Whitehouse
BBC News Online science editor

Many scientists are keen to plan for a Pluto encounter as the planet and its large moon, Charon, represent one of the true frontiers in the solar system that no spacecraft has ever visited.
This is despite the fact that the money for a mission to Pluto is in jeopardy as Nasa contemplates its future spending plans.

If scientists do not make plans now and be ready to act swiftly if the money becomes available, they may miss a golden opportunity to study the planet at the end of the Solar System.

They say if they do not get there soon, they may miss amazing sights that will not reoccur for almost 250 years.

Jupiter first

There are two reasons why scientists want to get there as soon as possible. The first has to do with its atmosphere.

Since 1989, Pluto has been moving farther from the Sun and as it gets colder its atmosphere will freeze out, so researchers want to arrive while there is a chance to see it.

The second reason is to map as much of Pluto and Charon as possible. The longer we wait, the more of Pluto and Charon will be shadowed for decades impeding the spacecraft's ability to take pictures in reflected sunlight.

Celestial mechanics say that an opportunity to launch to Pluto by way of Jupiter, which gives it a gravity kick, occurs in January 2006.

But given the uncertainty about the money that do not provide much time to get a probe designed and built. But if it does get off, scientists know what they want to do.

From Earth, the spacecraft will head to Jupiter, arriving just over a year later. Passing the Jovian system at 80,500 km per hour (50,000 mph) it will move on a trajectory that will arrive at Pluto and Charon as early as 2015.

The cameras on the spacecraft will start taking data on Pluto and Charon a year before it arrives and about three months from the closest approach - when Pluto and Charon are about 160,000 kilometres (100,000 miles) away - the spacecraft can make the first maps.

One day only

The busiest part of the Pluto-Charon flyby lasts a full Earth day. On the way in, the spacecraft will make the best global maps of Pluto and Charon in green, blue, red, and a special wavelength that is sensitive to methane frost on the surface.

The spacecraft will get as close as about 9,600 kilometres (6,000 miles) from Pluto and about 27,000 kilometres (17,000 miles) from Charon. During the half hour when the spacecraft is closest to Pluto or its moon, it will take close-up pictures in both visible and near-infrared wavelengths. The best pictures of Pluto will depict surface features as small as 60 meters (about 200 feet) across.

But even when it has sailed past Pluto the spacecrafts scientific life is far from over.

After passing Pluto it will retarget itself for an encounter with a Kuiper Belt Object (KBO) - one of the many large chunks of rock and ice that have been found in the cold outer reaches of the solar system in the past decade.

The team has not yet identified their target KBO, but scientists expect to find one or more the spacecraft can reach that are 50-100 kilometres (about 30-60 miles) across.

With so much pioneering science that such a probe could do researchers know they can make a case for the Pluto probe. They just hope that the politicians are listening.

Despite their proximity, Pluto and Charon are covered with bright frosts of differing compositions.

Water ice covers Charon, while Pluto's surface is predominantly nitrogen frost with traces of methane and carbon monoxide ices.

The Pluto/Charon system has a highly elliptical orbit around the sun. In 1989, Pluto was as close to the Sun as it gets during its long year - less than 30 astronomical units (AU), or 30 times the distance between Earth and the Sun. That distance nearly doubles just half a Pluto year later, to 50 AU in 2123.

As Pluto recedes from the Sun, much of its thin nitrogen atmosphere will condense as frost on the surface. This periodic reappearance of fresh frost takes place every Pluto year (248 Earth years) and is the reason that Pluto's is one of the most reflective surfaces in the solar system.

[blam]

"Any chance we can get those scientist to take some politicians with them when they fly by Pluto?"

I would ante up a few bucks to include Clinton, Condit and Daschle.

[Calvin Locke]

I thought Pluto's orbit was oval (eliptical?) to the extent that it slips inside the orbit of Neptune a portion of the time?