Nasa’s New Horizons prepares to take a closer look at Pluto

Nasa’s New Horizons prepares to take a closer look at Pluto

Scientists don’t know a lot about Pluto, but all that is about to change as a Nasa spacecraft is on its way to take a closer look


New Horizons will make its closest approach to Pluto July 14.
New Horizons will make its closest approach to Pluto July 14.
Photo: Reuters

After travelling almost 10 years, an unmanned Nasa spacecraft will make a close shave past Pluto today, offering scientists a detailed glimpse of the dwarf planet’s surface for the first time.

New Horizons is about the size of a baby grand piano and has been described as the fastest spaceship ever built, currently moving at a speed of 49,570km/h.

But there were some jitters on Monday as the US$700 million spacecraft sped toward the last undiscovered frontier in the solar system.

According to principal investigator Alan Stern, there is a one in 10,000 chance that the spacecraft could be lost in a collision with debris around Pluto, long considered the farthest planet from the Sun until it was reclassified as a dwarf planet in 2006.

The closest approach is set for tonight at 7.49pm Hong Kong time. Nasa TV coverage begins at 7.30pm.

But it will be hours before scientists hear back from the spacecraft – the first craft to visit an unexplored planet since the NASA Voyager missions launched in the 1970s – because New Horizons will be busy snapping pictures and collecting data.

It is supposed to send a “phone home” signal to Earth at 4.20am tomorrow morning, but that will take nearly five hours to reach scientists.

So Nasa won’t announce until about 13 hours after the flyby, at 9.02am on Thursday, whether or not the spacecraft survived the high-speed encounter.

“While I don’t lose sleep over this, the fact is, tomorrow evening is going to be a little bit of drama,” said Stern on Monday.

“Until we pass that point tomorrow evening we won’t really know with certainty that we cleared the system and that there were no debris strikes.”

Shooting gallery

Stern said experts have searched for potential debris and haven’t found any of concern.

But spaceflight is a risky business, and Stern described the Kuiper Belt, where Pluto resides on the edge of the solar system, as “more or less a shooting gallery, with lots of small primordial comets and other things much smaller than Pluto.”

Never before has a spacecraft ventured into the Kuiper Belt, and New Horizons has been on its way there for more than nine years – a journey of almost five billion kilometres.

It will pass by Pluto at a distance of 12,500km.

“We are flying into the unknown,” Stern told reporters.

New discoveries

What is currently known about Pluto could probably fit on a few index cards, Stern has said. New Horizons’ data will enable entire textbooks to be written about the mysterious celestial body.

Already, the pioneering NASA mission has confirmed the existence of a polar ice cap on Pluto, and found nitrogen escaping from Pluto’s atmosphere.

Stern also said the dwarf planet appears slightly larger than previously thought, with a radius of 1,185km.

Stunning visual features are coming into focus for the first time, including a light-colored heart shape nestled near a dark spot nicknamed “The Whale.”

And more detail is expected in the days to come, according to deputy project scientist Cathy Olkin.

“Right now, we are taking data that if you could transport (New York’s) Central Park to Pluto you would be able to identify the ponds in Central Park, that is the kind of resolution we will be getting,” she said.

“We are going to be making stereo maps so that we can see how tall the mountains are and how low the valleys are,” Olkin added.

Fossil of solar system 

Next, scientists will watch the sun rise and set behind Pluto, use New Horizons’ seven instruments to create a full picture of Pluto and its five moons, and study the dust in the outer solar system and the atmosphere around Pluto and its largest moon, Charon.

 Learning more about Pluto has captured the public’s attention because it speaks to the origins of the Earth and the larger questions of whether life could exist elsewhere, according to NASA’s John Grunsfeld, associate administrator of NASA’s science mission directorate.

 “The Pluto system is a fossil remnant of the beginnings of our solar system,” Grunsfeld said.

 “We are going to learn about where we are coming from,” he said.

 “It is opening up a new realm of exploration.”

Andrew Cheng, 63, helped develop a key component of the NASA New Horizons Pluto probe at the Johns Hopkins University Applied Physics Laboratory.
Photo: The Washington Post


Here’s a rundown on Pluto, a 20th-century discovery about to become the 21st-century darling of astronomers:


Pluto is the only planet (OK, now former planet) in our solar system discovered by an American. Astronomer Clyde Tombaugh spotted the dot in 1930 from Lowell Observatory in Flagstaff, Arizona. The name Pluto came from a British schoolgirl, Venetia Burney, then 11, based on the mythological god of the underworld.

Tombaugh died at age 90 in 1997, nine years before New Horizons took flight. A smidgen of his ashes is on board. Burney died in 2009, also at age 90. A student-built dust counter aboard New Horizons – from the University of Colorado at Boulder – is named after her.

Five moons: 

Big moon Charon was discovered in 1978 by Americans using the US Naval Observatory in Flagstaff, followed by little moons Nix and Hydra in 2005, Kerberos in 2011 and Styx in 2012. The Hubble Space Telescope revealed all four baby moons. Astronomers stuck to underworld undertones when it came to the names.

New Horizons will hunt for more moons, but at this point, they would have to be pretty elusive — scientists guess probably less than a mile across. The Pluto empire, complete with six bodies, at least for now, is like its own mini solar system.

Forget the sunglasses: 

Pluto is so far from the sun – between 4.5 billion and 7.4 billion kilometers – that twilight reigns. At high noon on Pluto, it looks as though it would be dawn or dusk on Earth. And let’s not forget the frigid weather, given its distance from the sun. Temperatures can plunge to minus 240 degrees Celsius. 

Pluto’s orbit is extremely oblong, plus it’s tilted. It takes 248 years for Pluto to orbit the sun. Thus, it’s only made it about one-third of the way around the sun since its discovery in 1930. Every so often, Neptune’s orbit exceeds Pluto’s, putting Neptune slightly farther out.

First a planet, then it's not: 

Pluto is the only planet to get kicked out of the solar system club.

Just seven months after New Horizons rocketed away from Cape Canaveral, Florida, the International Astronomical Union declassified Pluto as the ninth planet for technical reasons. Instead, it became a dwarf planet. The decision left the solar system with eight full-fledged planets, with Mercury replacing Pluto as the smallest.

On Monday, scientists said measurements by New Horizons showed Pluto to be 2,370km in diameter, a little bigger than earlier estimates.

The twilight zone: 

Pluto is the biggest object in the icy Kuiper Belt, also known as the third zone after the inner rocky planets and outer gaseous giants. It’s also called the Twilight Zone because of its great distance from the sun.

The Kuiper Belt (pronounced KIE-per) is full of comets and other small frosty objects. It’s named after the late Dutch-American astronomer Gerard Kuiper, who proposed a bevy of small bodies beyond Neptune back in the 1950s. The New Horizons team hopes to go after a smaller Kuiper Belt object following the Pluto flyby, provided a mission extension is approved.


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