New Horizons mission - Q&A


Written by Naomi Pequette.

Written by Naomi Pequette. 

Tell us a little bit about the New Horizons mission.

The goal of New Horizons is to study the geology and atmosphere of Pluto and its largest moon, Charon as well as to map both of their surfaces. New Horizons was launched on January 19, 2006. To do this, scientist will utilize the seven instruments aboard the spacecraft, which include multiple images and spectrometers. The spacecraft traveled for nine years and three billion miles to flyby Pluto, providing us with the highest resolution images ever of Pluto and Charon, as well as a wealth of other scientific information.

How close did new horizons get to Pluto?

At its closest approach, New Horizons will be just 6,000 miles away from Pluto. That may sound like a big distance, but will provide us with images that are 1000 times higher resolution than the images of Pluto taken by the Hubble Space Telescope. If we flew over Earth at that same altitude, you would be able to see a surprising amount of detail. For example, if you flew over New York City at that same distance, you could count the number of ponds in Central Park.

Is there any life on Pluto?

Not that we know of. It would be extremely difficult for life as we know it to survive on Pluto. The sun is extremely far away (3.67 billion miles on average). At this distance, temperatures can be as low as -389 degrees Fahrenheit. Liquid water, which is essential to life as we know it, couldn't exist at these super cold temperatures. Not only does water freeze at these temperatures, so do methane, nitrogen, and carbon monoxide. In fact, New Horizons scientist believe some of the brighter areas we observe on Pluto could be fresh nitrogen snow! The warmest temperature nitrogen snow could exit at is -346 Fahrenheit. Pluto also has a very thin atmosphere, which wouldn't be conducive to life. So, there is very little chance that life could survive on the surface of Pluto.

Where does Pluto get its red color from?

In part, Pluto's red/orange color comes from reactions between cosmic rays and solar ultraviolet light interact with methane in Pluto's atmosphere and on its surface. 

The new Horizons Team just released a new color photo on Wednesday that shows there may be even more colors on Pluto than we thought. Those colors indicate different geologic, tectonic, or morphologic origins. This tells scientists that some of the surfaces on Pluto are older, and some are very young and still changing geologically. They are still awaiting more data before speculating further on what the different surfaces could be.

One surprise in these images is you can see a large, deep red spot on Charon. That spot came from Pluto. It has been known for a while that Pluto is "leaking" nitrogen, and the could be getting caught by Charon's gravity. That nitrogen would burn away near Charon's equator, where it is always sunny, but could stick around the poles for decades, staining the rock on Charon Red.

How long will it take to get the data back from new horizons?

While we will see some images from the fly-by as soon as tomorrow, it will take 16 months for all of the data from New Horizons to arrive at Earth. There are a combination of factors that cause that timeframe to be so long.

The smallest issues is actually the time it takes for data to arrive to Earth from New Horizons. It takes the signal about 4 hours to travel from Pluto to Earth at the speed of light.

However, that long distance that the signal has to travel means that it is very weak by the time it arrives at Earth. Only NASA's Deep Space Network can detect New Horizon's faint signals. Scientists have to schedule time on the Deep Space Network ahead of time to make sure that the spacecraft is only sending data when the Deep Space Network radio telescopes are pointed in its direction. This network of radio telescopes is also listening from signal from several other Deep Space Missions.

However, the biggest factor is New Horizons transmission rate. Remember dial up internet? Well slow that down even further and that is the speed at which New Horizons is transmitting data - 1-3 kilobits per second. The images that are taken by one of New Horizons high resolution cameras, LORRI, are 1024 pixels square. Those images can be compresses so that they are 2.5 Megabits when they are transmission. At a 3 kilobit per second transmission, it takes 14 minutes to return one LORRI photo to Earth (not including the signal travel times). During the fly-by New Horizons is expected to capture 150 high-resolution photos along with lots of other scientific data.

Is Pluto a planet?

No, Pluto is now considered a dwarf planet. Shortly after New Horizons was launched, the International Astronomical Union met and voted on a definition of a planet. This had not been defined since the Ancient Greeks discovered the first planets. The new official definition is:

1) Is in orbit around the sun
2)Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3)Has cleared the neighborhood around its orbit

Pluto meets the first two criteria, but there is a lot of debris and other Kuiper Belt Objects. Any non-satellite body that meets the first two requirements is now called a dwarf planet. Pluto is the largest dwarf planet.

What are Pluto's moons named after?

Pluto was named after the Roman god of the underworld. Pluto's moons are named after Greek and Roman underworld myths as well. Charon is ferryman who carries souls of the nearly deceased across the river Styx (another one of Pluto's moons). Nyx was the goddess of the night, Hydra was a giant water snake and one of Hercules twelve labors and Kerberos was the gigantic muti-headed hound that guarded the gates of Hades.

How big is Pluto compare to earth?

Pluto is a pretty small object. It is only half the width of the United States. Charon, Pluto's largest moon, is about half the diameter of Pluto. Hydra, another one of Pluto's moons, could fit between Denver International Airport and Evergreen!

How big is Pluto?

Pluto is about 2/3 the diameter of Earth's moon. New Horizons has already found that Pluto is larger than expected, however. The new estimate is about 1,472 miles.

What's your favorite Pluto fact?

Pluto's moons don't actually orbit Pluto; they orbit a common center of gravity between Pluto and Charon. Charon is large for a moon - 11% as massive as Pluto. This causes Pluto to "wobble" as Pluto and Charon orbit each other. It also causes some of Pluto's smaller moons have a very chaotic trip throughout their orbit. Scientists have found that Nix and Hydra tumble around and change their spin unpredictably.

What is the next plan for new horizons?

The New Horizons team hopes they will receive funding to continue to study the Kuiper Belt and fly-by a couple of small icy objects there.

Why isn't New Horizons orbiting Pluto?

To arrive in just 9 years, New Horizons has to be traveling at a tremendous speed. In fact, New Horizons holds the record for the spacecraft ever launched. It left Earth at an impressive 36,000 miles per hour! It arrived at the moon in just 9 hours, which is ten times faster than the Apollo missions. As it flew by Pluto, New Horizons was traveling at close to 31,000 miles per hour. It would take a tremendous amount of fuel to be able to change the spacecraft's course and be captured by Pluto's gravity- way more than New Horizons ever had on board. If we wanted to send a spacecraft to orbit Pluto, it would need to arrive at, and also travel at, a much slower speed. At those speeds, it would take 50 years or more to travel from Earth to Pluto. Right now, we don't have a fuel source to power the spacecraft that would last that long. So, we need some new technologies before we can send a satellite to orbit Pluto, or any spacecraft to land on Pluto's surface.


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