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13 July 2015updated 01 Jul 2021 11:40am

Liveblog: Nasa’s probe New Horizons will make history as the first spacecraft ever to reach Pluto

Nasa’s New Horizons spacecraft will be returning to humanity the first ever close-up images and scientific observations of Pluto and its moons. 

By Tosin Thompson

After almost ten arduous years of space travel, we’re nearly there. In less than 24 hours, Nasa’s spacecraft New Horizons (NH) will become the first space probe to reach Pluto.

Tomorrow, NH will zoom past Pluto at speeds of more than 48,000km per hour, and swoop to within about 12,500 km of its surface. NH will make it closest encounter with Pluto on July 14 at 12:50 pm BST.

The NH team is working tirelessly to ensure the 700 million dollar mission runs smoothly.


NH entered directly into an Earth and Sun escape trajectory after its launch on 19 January 2006 at a speed of 58,536km per h – 100 times faster than the speed of a bullet train, making it the fastest spacecraft to ever leave Earth’s orbit.  NH got a speed boost from Jupiter’s gravity in 2007. Without it, the probe wouldn’t have reached Pluto until the year 2036. After NH’s trip to Pluto, it will encounter an object called “potential target 1” in January 2019 before heading out of the Solar System.

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At the moment, NH is less than 1 million km away from Pluto, its largest moon Charon (half the size of Pluto), with which it forms a double planet system because of its large size relative to Pluto, and its four newly discovered moons: Hydra, Nix, Styx and Kerberos.

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At the moment, Pluto is about 5 billion km away from Earth. As the speed of light is roughly 1 billion km per hour, it would take about five hours for light, the fastest thing in the universe, to reach the probe. Communicating with the probe every five hours is just too long, and so the probe has to be able to operate on its own without commands from Earth during the fast flyby period.

Pluto is famous for its small size and its demotion from full planet to dwarf planet status in 2006, but despite this, not much is known about it. Pluto carries a lot of mystery; it’s the most distant and least explored planet in our Solar System, and therefore presents challenges to anyone bold enough to come close to it.

NH’s imager Long Range Reconnaissance Imager (LORRI) has captured several images of the surface of Pluto, each image being more detailed than the last as NH moves closer towards the dwarf planet. 

These images of the surface of Pluto have allowed the NH team to indentify an elongated dark area (the whale”), a bright donut-shaped feature about 350km across (“the donut”), liner features (possibly cliffs), a circular feature (possibly an impact crater), and a large heart-shaped area some 2,000km across (possibly Pluto the dog). 

I ask Henry Throop, a senior research scientist of Planetary Science Institute, what the significance of the mission is:

The significance of the mission really is that this is the first spacecraft to visit the last unexplored planet in the solar system. Over the last decades, the US and other countries have sent dozens of spacecraft exploring the solar system. We understand Mars well, we’ve seen the rings of Saturn up close, and we’ve explored some fascinating worlds like Titan and Europa. But Pluto is further away, colder and smaller than any of these — and it’s a very different place

Its history is wildly different than anything we’ve seen up close. So we’re trying to put Pluto in the context of what we do know about the solar system. In some ways, Pluto shares a lot in common with the thousands of bodies in the Kuiper belt — in effect it’s a ’third type of planet’, to complement the rocky terrestrial planets like Earth, and the gas giants such as Jupiter. By visiting Pluto, we expect we’ll also be able to learn a great deal about this whole region of the solar system, and the large, diverse set of bodies there: history, composition, physical processes on the surface, and so forth,” he adds. 

Updates to follow.


14/07/15  12:25 NH has sent us a new picture! This one was taken at 766,000kms from Pluto:

So pretty!

The reaction from the team:

12:31 To settle the decade-long debate on Pluto’s size: The mission scientists have found Pluto to be 2,370kms in diameter  the distance between Massachusetts and Kansas City.

The result confirms what was already suspected: After the orbit of Neptune, Pluto is the largest known object in the Solar System.

12:42 NH is 16,000km from Pluto, just 8 minutes to closest approach.

12:50 NH made it! Mission complete!

12:52 Celebrations at the New Horizons headquarters:

13:05 Let us not forget about Charon. NH is minutes away from passing Pluto’s largest moon.

13:22 NH will have to ensure the images of Pluto during its closest encounter are safely in its onboard before it calls home again. This is not expected to happen until just after midnight (GMT) into Wednesday. So for now, we wait… In the meantime, here’s a timelapse of NH’s encounter with Pluto:

13:48 The Solar System family portrait, with Pluto in it this time: 

14:20 Senior editor of the Planetary Society Emily Lakdawalla describes the surface of Pluto on her blog using the newest photo.

16:11 I’m sorry.

16:37 Stephen Hawking thanks Nasa and the New Horizons team for their historic flyby of Pluto: 

Stephen Hawking NASA Statement

I would like to congratulate the New Horizons team and NASA – National Aeronautics and Space Administration for their historic flyby of Pluto. The culmination of a decade long mission, I can’t wait to see what new information the New Horizons spacecraft will reveal about our distant relative. – SH

Posted by Stephen Hawking on Tuesday, 14 July 2015

15/07/15  9:45 Nasa’s New Horizons “phoned home” (the John Hopkins University Applied Physics Laboratory, to be exact) just before 2 am BST Wednesday to tell the team the mission was a resounding success.

After a very suspenseful 21-hour waiting period, the preprogrammed “phone call” was a series of 15 minute status messages through Nasa’s Deep Space Network. NH had been instructed to spend the day gathering as much data as it could, and not communicating with Earth until it left the Pluto system. 

NH’s principal investigator Alan Stern says in a press release

Following in the footsteps of planetary exploration missions such as Mariner, Pioneer and Voyager, New Horizons has triumphed at Pluto. The New Horizons flyby completes the first era of planetary reconnaissance, a half century long endeavor that will forever be a legacy of our time.” 

Applied Physics Laboratory Director Ralph Semmel says in a press release:

On behalf of everyone at the Johns Hopkins University Applied Physics Laboratory, I want to congratulate the New Horizons team for the dedication, skill, creativity, and determination they demonstrated to reach this historic milestone. We are proud to be a part of a truly amazing team of scientists, engineers, and mission operations experts from across our nation who worked tirelessly to ensure the success of this mission.”

9:50 President Obama thanked Nasa today:  

NH is now hundreds of thousands of miles from Pluto, wandering in darkness…

16/07/15  10:15

Nasa unveils new high-resolution photographs sent from New Horizons, the most detailed ever of Pluto and its moons.

10:30: It will take 16 months for NH to beam all the data its collected back to Earth. Patience is a virtue. Check out Nasa’s New Horizons website for more information on the New Horizons mission, including fact sheets, schedules, video and new images. 

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