New Horizons Opens A Path to Pluto

Let’s watch the 2006 launch of the fastest spacecraft ever to leave our planet.

Put on your hard hat and watch your speaker volume as an Atlas V rocket, Centaur rocket, and five solid rocket boosters light up.

Yeah. That baby took only 9 hours to reach the Moon.

On August 25, 2014, New Horizons crossed Neptune’s orbit and is now in or very close to the Kuiper Belt.

New Horizons will reach Pluto in July 2015

The need for speed

Nine and a half years seems like a long time, but it is really a very short flight. As a comparison, the European Space Agency’s Rosetta mission took 10 years to intercept a comet midway between the orbits of Mars and Jupiter.

New Horizons started out at around 36,400 mph (58,500 kph). It hit 47,000 mph (76,000 kph) after a gravitational boost from Mars in 2006, and then 52,000 mph (84,000 kph), 35% of lightspeed, in 2007 thanks to another gravity assist, this time from Jupiter.

The spacecraft has to travel that fast to get to Pluto – some 39 times as far from the Sun as we are – inside of a decade.

The green line marks how far New Horizons had gotten in 2010.  Source

The green line marks how far New Horizons had gotten in 2010. Source

We’ve seen how hard it is to apply the brakes at the planet Mercury. How are they going to park the hurtling speed demon New Horizons at Pluto?

Well…they aren’t.

For one thing, it would take more fuel than New Horizons can carry. For another, the detailed data needed for an orbital insertion just doesn’t exist yet.

So little is known about the Solar System environment beyond Neptune that New Horizons mission planners are hoping there isn’t any debris in the spacecraft’s path.

Pluto is so far from Earth, this is the best image we can get of it:

Hubble views of Pluto.  Source

Hubble views of Pluto. Source

New Horizons was sent, basically, to improve that picture and to get information for future Pluto missions.

The instruments

Here, in less than 140 characters, is what we know about Pluto today.


While the July 2015 flyby of Pluto and its moons will only last hours, we will start getting images at the start of May 2015 that will be better than anything the Hubble telescope can do. That’s cool in and of itself, but it’s also very necessary to know, before the spacecraft gets too close, if Pluto has any rings or extra moons they need to steer around.

That “Pluto photo op” will continue for roughly three months, when New Horizons will be quite far along in its journey into the Kuiper Belt.

All seven instruments on New Horizons are working, despite the long and dangerous voyage. The craft has been in hibernation most of the way but does wake up at times to test the instruments and take observations.

They will be very busy during the flyby.

First there are Ralph and Alice. Yes, the telescope was named Ralph as a Honeymooners reference (Alice’s namesake was an instrument aboard Rosetta).

Ralph has two channels – visible (MVIC) and infrared (LEISA). Its object is to map Pluto and Charon, which is Pluto’s largest moon. Alice is an ultraviolet imaging spectrometer that is going to check out Pluto’s atmosphere.

REX (“radio experiment”) handles all the communications with Earth. It will also study Pluto’s atmosphere and study Pluto’s weak radio emissions, which will in turn tell scientists what the temperature is there (hint: it’s cold…very, very cold).

LORRI (the Long Range Reconnaissance Imager) is the telescope that will be giving us those better-than-Hubble views. It has already provided a historic image of Charon orbiting around Pluto:

No one has ever been able to see this before!

No one has ever been able to see this before! Source

At Pluto, LORRI will be snapping images of the surface with a roughly 100-yard (100-meter) resolution.

SWAP (“solar wind around Pluto”) is a plasma sensor to measure, yes, the solar wind around Pluto. Its objective is to detect Pluto’s magnetic field and to see how fast Pluto’s atmosphere is escaping.

At close encounter, PEPSSI (“Pluto Energetic Particle Spectrometer Science”) will be trying to detect neutral atoms escaping Pluto’s atmosphere and picking up an electrical charge from the solar wind.

SWAP and PEPSSI results will be useful, believe it not, in determining whether Pluto has some of the characteristics of a comet.

And then there’s the Venetia Burney Student Dust Counter, built and managed (with the assistance of space scientists) by University of Colorado, Boulder, students.

Other public outreach on the New Horizons mission includes a golden CD inscribed with over 430,000 names. Some of Pluto discoverer Clyde Tombaugh’s ashes are on board, as well as a piece of SpaceShipOne and other mementos.

After its hours-long encounter with Pluto in 2015, New Horizons will then continue on further into the Kuiper Belt where debris left over from the Solar System’s formation orbits.

Right now the Hubble Telescope is looking for specific Kuiper Belt objects to study after the main encounter. The final target will be selected after the Pluto flyby, based on how much fuel New Horizons has left for maneuvering.

The mission is expected to officially end in 2026. The spacecraft should eventually leave the Solar System in 2047, heading for the constellation Sagittarius.

In writing this, it has been difficult not to call Pluto either a planet or a dwarf planet. Which is it? Stay tuned for next week’s episode in our space trek through the outer reaches of the Solar System, where no living human has gone before.

In the meantime, let’s enjoy some of the images New Horizons has already sent back of Mars and Jupiter. All images are from NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Goddard Space Flight Center.

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