A Blog by

Spacecraft Bound for Pluto Awakens From Multi-Year Nap

After hibernating for much of the past seven years, the New Horizons spacecraft awoke today on Pluto’s doorstep. Near the margin of the observable solar system, the piano-size space probe is so far from home that even signals traveling at the speed of light take nearly 4.5 hours to get to Earth.

This evening, just before 6:30 p.m. Pacific time, one of those signals broadcast the beginning of a new phase in the spacecraft’s mission: Way out there, in dark, cold interplanetary space, New Horizons is awake and ready to begin studying Pluto.

Today, the probe is still 260 million kilometers from Pluto, the dwarf planet at the center of a simmering debate over the definition of planethood. But New Horizons is the fastest space probe ever launched, and it is quickly closing that gap. Next July, its 5 billion-kilometer journey to Pluto will come to an end when it flies by the little guy and spends a frantic few hours quickly gobbling up as much data as possible. Then, the spacecraft will continue on to the icy Kuiper Belt, where more rocky targets wait in the darkness.

New Horizons entered a long period of mostly hibernation about one year after it launched, in 2006. In February 2007, it swung by Jupiter and grabbed a gravity assist from the most massive planet in the solar system. After collecting some data about the giant’s atmosphere, magnetic field, and enigmatic moons, the spacecraft whizzed away and silently slipped into slumber. But it awoke a few times during those seven years so scientists could check that its instruments were still healthy. Before now, Neptune was one of the last things New Horizons saw during a brief period of alertness. It was late August, and the spacecraft had crossed Neptune’s orbit 25 years to the day after Voyager 2 arrived at the ice giant.

This journey to the edge of our planetary system has been in the making for more than a quarter-century, and it promises a wealth of discoveries. Pluto is so far away that even the Hubble Space Telescope can’t make out its surface features. Is it a geologically active world, with geysers? And what about its many moons? There are at least five of them, maybe more, and no one knows what they look like. One of them, Charon, is so big in relation to Pluto that it actually forms a binary planet with the dwarf — the two bodies revolve around a point in the space between them.

There are so many questions waiting to be answered by New Horizons over these next months. But we will have to wait. For now, let the spacecraft shake itself from slumber and prepare to get to work. We have a mission to Pluto!

20 thoughts on “Spacecraft Bound for Pluto Awakens From Multi-Year Nap

  1. Hi,
    Good news for world human being, there is some where to escape critical world in near future. No where to go, select there but how?
    Suggest for someone here. Thailand, the land of developement gone so far.

  2. The long space mission, the hibernation, the number 9 door reminiscent of the Monolith in 2001 (Space Odyssey)

    “It was a slow, tedious business, but the crystal monolith was patient.”

    Our committees have had their fun and games, it is time for Pluto to return as the Prodigal Planet – come on, it has more moons than all of our little rocky group of 4 who sit close to the star player, and it has cleared its local orbital zone.

    “No one could have imagined, back in the mid-sixties, that the exploration of the moons of Jupiter lay not in the next century but only fifteen years ahead. Nor had anyone dreamed of the wonders that would be found there – although we can be quite certain that the discoveries of the twin Voyagers will one day be surpassed by even more unexpected finds. When 2001 was written, Io, Europa, Ganymede, and Callisto were mere pinpoints of light in even the most powerful telescope; now they are worlds, each unique, and one of them – Io – the most volcanically active body in the Solar System.”

  3. Your follow-up article is missing the point,again.Just because the HST can’t see Pluto doesn’t mean other methods can’t acomplish that.spacenow.com.br has covered successfuly the rotations of both Pluto and Charon and has shown it to millions of visitors to our website(including NASA,that visits us every month) ,ESA and countless other institutions and Universities around the globe.Pluto’s giant mountain could reach 500 kms and Charon’s supervolcanoes are building Pluto’s main moon from the inside-out.

  4. @Noetic many moons does not a planet make. If Pluto were a planet it would be only by tradition. Frankly I think if it’s round but not glowing it’s a planet, but that definition includes a lot of asteroids.

  5. @Kudzu, agreed – it’s not the moons per se, but the fact that these indicate it MAY have cleared its orbital zone. More successfully than Mars, if this is currently the most asteroid-peppered planet.

    But maybe tradition is the best yardstick, if you look out into the cosmos you see one big light by day, a big light by night (sometimes), stars and “wandering stars” (i.e. the planetos – or whatever the Greek plural form is).
    Oh you might also see “shooting stars” and comets and supernovae and some man-made objects, both extra and intra atmospheric (oh, and the aurorae, also cosmic phenomena).

    But this “dwarf planet” thing is a cop-out, they realise they cannot classify it an asteroid, or space debris (Kuiper Belt or not). So just follow tradition and call it a planet. Of course with its partner Charon they make up planets 9 and 10. And then you get up to 16 planets when you count Eris, Makemake, Haumea, Sedna, 2007_OR_10, Quaoar, and Orcus (great mix of hyper-modern and traditional names).

    Great photo collages here


  6. Again, Pluto and its unfinished moon, Charon have been thoroughly imaged during 6 years by spacenow.com.br and their full rotations documented in many photographs.Images are with the IAU and spacenow is only awaiting confirmation to name the surface features found there, mainly, Pluto’s gigantic mountain. http://spacenow.com.br/pluto6.html

  7. @Kudzu Many planetary scientists reject the idea that a celestial object must clear its orbit to be a planet. That “requirement” was concocted by four percent of the IAU, who voted on the controversial resolution that demoted Pluto. Most were not planetary scientists but other types of astronomers, and they were looking for a reason to exclude Pluto and keep the number of solar system planets artificially small. No solar system planet fully clears its orbit of asteroids. And the farther an object is from its parent star, the bigger an orbit it has to “clear.” If Earth were in Pluto’s orbit, it would not clear that orbit either. This means the IAU definition could result in the absurdity of the same object being classed as a planet in one location and not as a planet in another location.

    The IAU decision was opposed by hundreds of professional astronomers in a formal petition led by New Horizons Principal Investigator Dr. Alan Stern. These planetary scientists hold a different definition of planet, known as the geophysical definition. The geophysical planet definition first and foremost defines celestial objects by their intrinsic properties rather than by their location. If an object is not a star and is large enough to be squeezed into a round or nearly round shape by its own gravity, it is a planet. This is the basis for supporting Pluto’s planethood, not tradition or emotion.

    Planets are distinguished from asteroids in that asteroids are shaped only by their chemical bonds because they are so small. An object has to reach a certain threshold of mass and size for gravity to take over in determining its shape. Pluto is well beyond that threshold. And it has all the features larger planets have, including geology, weather, and differentiation into core, mantle, and crust. The only difference is that it is smaller.

  8. “One of them, Charon, is so big in relation to Pluto that it actually forms a binary planet with the dwarf — the two bodies revolve around a point in the space between them.”

    How can that be? Maybe a black hole is causing this?

    1. @Roy: No, that’s just how physics works; the Earth and moon orbit around their common center, but it lies beneath Earth’s surface. I Pluto\Charon’s case the two bodies are trying to orbit each other.

  9. @Laurel, thanks for filling in the background on “our committees have had their fun and games” – that is very interesting to hear the true story. I did not really follow the debate at the time but I am glad to hear that the controversy still persists in the proper circles.

    Most moons would meet the criteria for planets too I suspect (not a star, spherical due to gravitational effects) – so a planet would also need not to be a moon too I venture. And then what about a neutron star, since it is no longer luminous (does it still have significant short wavelength black body emission?) and it meets the spherical and non-moon criterian, does it need a special rule to remain a star, or is it more logically a planet. And by extension, what about planets not in a reasonably tight orbit around a star – they surely remain planets and don’t become space junk do they? (Must check, do all the 8 | 9 | 16 Solar planets have their sun-self barycentres within Sol’s interior?)

    Thinking a bit more on this, I would imagine that all planets (and moons for that matter) were necessarily completely molten in their infancy, in order to take on essentially spherical shapes. And as for the geoidic shape of earth, surely centripetal force alone could not stretch the equatorial radius 21 km more than the polar radius had the earth not been completely molten. Surely the present equatorial bulge could only be established while spinning a liquid globe and having it cooling in this shape on the “potters wheel”?
    And to put this bulge into perspective, it is about 2,2 times the height of Everest – so that Mount Chimborazo in Ecuador is at significantly larger radius from the geocentre (6300 m aMSL compared with 8800 m for Everest).

    It’s been fascinating to read today of the solid – “liquid” layers in the Earth’s core. Our inner core is solid while the outer core is extremely low viscuous magma (allowing the inner core to spin faster than the crust), and the tectonic plates ride on a slippery layer above the highly viscuous mantle. Since 80% of our internal thermal energy is radioactive generation and 20% residual from the thermal energy during accretion, one might expect Pluto to still have some sort of internal molten phases too – putting it firmly back in the planet family. Though its surface area to mass ratio and zero atmosphere would mean far higher heat loss, and it does not have any solar irradiation to speak of – so it may not have any molten phases left (too late I checked : the Wikipedia article suggests a water/ice layer surrounding the solid core)

    PS – For us ‘traditionalists’, the word planet (“wandering” adjective applied to an apparent star) seems to have been acquired by Modern Greek (as planitis, planites(plural) ) after this route via Latin and French

    Planet : coined 1250-1300
    < Middle English planete
    < Old French planète
    < Late Latin planeta, planetes (but found only in plural planetae)
    < Greek (astéres) planetai literally: (stars) wandering

  10. All cosmonautical research and space explorations cost all Earth’s human societies billions of dollars yearly and are only curiosities to them . If we compare it to the amount of money which are being spend for basic human needs and problems all people are facing on this Earth , we can not avoid to come to conclusion that those who are responsible for proper distribution of money are committing highest crime against mankind of this Earth for not managing earn money properly for basic needs of people for job creation , for health ,for proper education for all ,etc. Because those who are responsible for this kind of mismanagement are self appointed and corruption supported social law making positions they are in the power of making decisions of what is right and what is wrong, that’s why they never make right decision that they are wrong and are criminals. All we are only waiting for the end of this unjust human made jungle wrongly called “civilization”

    1. @Dusan And yet the amount we spend on fast food dwarfs this. Fast food. It is not our leaders that mismanage, it is us. If we, the common people actually wanted things to be different we could make it so in a week. But we don’t. We enjoy our lattes and cheeseburgers and big screen TVs. At least space exploration stimulates technological development; it gives us new tools that are shared, be it ever so slowly, with the whole world. LED lighting illuminates African villages, waste recyclers clean rivers across the glove, solar panels fight climate change. What excuses do we, the idle well off have?

      1. @Kudzu and @Dusan

        Both of you have valid points.

        As per facts coming out of Davos 2016, why don’t we “politely ask” the 62 private individuals who own as much wealth as the lowest 50 percentile to fund the future via “blue sky, deep space” research and reallocate all that national tax-funded research money to poverty alleviation?

        And assign all the IP from the research to Open Source and Public Domain trustees?

  11. The irony is quite poignant now.

    With the prediction of a 10 M_earth post-Neptunian planet to explain gravitational perturbations of 4 other planets (which I assume are J, S, U, N) we are now all the way back to the Planet X situation of what was it, nearly a century ago.

    If we have planet X now, then Pluto must be Planet iX, the unplanned child birthed by accident.

    If this is not the time to reinstate our prodigal 9th planet, whenever will it be?

  12. And for those who don’t have a problem reading copy-and-paste comments 😛

    Some FYI facts that are interesting

    [2016-01-20]: Planet X suggested to have M_X = [5 : 10] M_e and mean orbital radius of about 600 AU I gather, this is how that would compare with the century old search for Planet X …

    In 1906, convinced he could resolve the conundrum of Uranus’s orbit, he began an extensive project to search for a trans-Neptunian planet,[15] which he named Planet X. The X in the name represents an unknown and is pronounced as the letter, as opposed to the Roman numeral for 10 (at the time, Planet X would have been the ninth planet).

    After revising his predicted possible locations, Lowell conducted a second search from 1914 to 1916.[15] In 1915, he published his Memoir of a Trans-Neptunian Planet, in which he concluded that Planet X had a mass roughly seven times that of Earth—about half that of Neptune—and a mean distance from the Sun of 43 AU. He assumed Planet X would be a large, low-density object with a high albedo, like the giant planets. As a result, it would show a disc with diameter of about one arcsecond and an apparent magnitude of between 12 and 13—bright enough to be spotted.

    Separately, in 1908, Pickering announced that, by analysing irregularities in Uranus’s orbit, he had found evidence for a ninth planet. His hypothetical planet, which he termed “Planet O” (because it came after “N”, i.e. Neptune),[18] possessed a mean orbital radius of 51.9 AU and an orbital period of 373.5 years.[11] Plates taken at his observatory in Arequipa, Peru, showed no evidence for the predicted planet, and British astronomer P. H. Cowell showed that the irregularities observed in Uranus’s orbit virtually disappeared once the planet’s displacement of longitude was taken into account.[11] Lowell himself, despite his close association with Pickering, dismissed Planet O out of hand, saying, “This planet is very properly designated “O”, [for it] is nothing at all.”[19] Unbeknownst to Pickering, four of the photographic plates taken in the search for “Planet O” by astronomers at the Mount Wilson Observatory in 1919 captured images of Pluto, though this was only recognised years later.[

    Lowell’s sudden death in 1916 temporarily halted the search for Planet X. Failing to find the planet, according to one friend, “virtually killed him”.[21] Lowell’s widow, Constance, engaged in a legal battle with the observatory over Lowell’s legacy which halted the search for Planet X for several years.

    On 18 February 1930, after searching for nearly a year and examining nearly 2 million stars, Tombaugh discovered a moving object on photographic plates taken on 23 January and 29 January of that year.[24] A lesser-quality photograph taken on January 21 confirmed the movement.[22] Upon confirmation, Tombaugh walked into Slipher’s office and declared, “Doctor Slipher, I have found your Planet X.”[22] The object lay just six degrees from one of two locations for Planet X Lowell had suggested; thus it seemed he had at last been vindicated.[22] After the observatory obtained further confirmatory photographs, news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930. The new object was later precovered on photographs dating back to 19 March 1915.[20] The decision to name the object Pluto was intended in part to honour Percival Lowell, as his initials made up the word’s first two letters.

    Almost immediately, some astronomers questioned Pluto’s status as a planet. Barely a month after its discovery was announced, on 14 April 1930, in an article in the New York Times, Armin O. Leuschner suggested that Pluto’s dimness and high orbital eccentricity made it more similar to an asteroid or comet … In 1931, using a mathematical formula, Ernest W. Brown asserted (in agreement with E. C. Bower), that the presumed irregularities in the orbit of Uranus could not be due to the gravitational effect of a more distant planet, and thus that Lowell’s supposed prediction was “purely accidental”.


    Brown, who tweets under the handle @plutokiller and who wrote the book “How I Killed Pluto and Why It Had It Coming,” said now may be the time to rewrite the textbooks yet again.

    Pluto, discovered in 1930, spent three-quarters of a century as the iconic ninth planet. Then, a decade ago, Pluto received a controversial demotion, in large part because of Brown.

    “My daughter, she’s still kind of mad about Pluto being demoted, even though she was barely born at that time,” Brown said. “She suggested a few years ago that she’d forgive me if I found a new planet. So I guess I’ve been working on this for her.”


Leave a Reply

Your email address will not be published. Required fields are marked *