Catching Up with New Horizons

by Paul Gilster on August 22, 2011

New Horizons continues on its inexorable way to Pluto/Charon, now some 21 AU out, which places it between the orbits of Uranus and Neptune. The latest report from principal investigator Alan Stern tells us that the 2011 checkout of the spacecraft was completed on July 1, a two-month process that included a test of the REX radio occultation experiment, coordinating with the Deep Space Network as the Moon interrupted a radio signal from Earth. According to Stern, spacecraft tracking over May and June shows New Horizons on a ‘perfect course’ toward the distant world, one that will demand no course correction until, at the earliest, 2013.

I wanted to bring Stern’s report into play here because of the image below, which shows Pluto’s newly discovered moon P4 along with the other moons now known in the system. The fact that I hadn’t yet run it told me that it was time to do some catching up with this impressive mission.

Image: These two images, taken about a week apart by NASA’s Hubble Space Telescope, show four moons orbiting the distant, icy dwarf planet Pluto. The green circle in both snapshots marks the newly discovered moon, temporarily dubbed P4, found by Hubble in June. The new moon lies between the orbits of Nix and Hydra, two satellites discovered by Hubble in 2005. It completes an orbit around Pluto roughly every 31 days. Credit: NASA, ESA, and M. Showalter (SETI Institute)

P4 (the name is temporary) was found during a search for rings around Pluto. At an estimated diameter of 13 to 34 kilometers, it’s the smallest moon yet discovered in this system. Obviously, the more we learn about Pluto/Charon, the better the New Horizons team will be able to plan for its brief period of close up observations. And it’s likely we’ll find still more tiny moons in a system that is thought to have been formed by a collision between Pluto and another large body in the early Solar System. P4 was found with Hubble’s Wide Field Camera 3 on June 28 and later confirmed through subsequent imagery. Still no signs of any Plutonian rings, however.

Meanwhile, John Spencer, a member of the New Horizons mission science team, has posted an interesting look at the effort to find a Kuiper Belt object that New Horizons will study after the encounter with Pluto/Charon. We’ve talked before about the Ice Hunters project, where volunteers can help pursue the search using the power of networked computers at home. Hunter now reports on his trip to Hawaii, which provided the chance to work with the Subaru telescope on the summit of Mauna Kea, an experience would-be astronomers can only envy. Spencer talks about recapturing ‘the romance of the old way of connecting with the universe,’ something many working astronomers seldom do these days, and describes the trip to the top:

After a night and a day of acclimatization, adjusting our bodies to the thin air, we climbed into 4WD vehicles and made the half-hour drive to the summit as sunset approached. It is always an amazing transition from the relative domesticity of Hale Pohaku and its mamane trees to the vast, alien, apparently lifeless landscape of the summit and its giant telescopes. This was the first time at Subaru for some in our group, so Josh Williams, the telescope operator, gave us a quick tour of the darkened, cathedral-like space of the dome, almost filled by the huge bulk of the telescope with its 8-meter diameter mirror. We also made quick trip around the catwalk outside the dome, to admire the fabulous view, before returning to the warmth and comfort of the control room, where we were to spend the night.

The work involved calibration observations, warm-up tests using near-Earth asteoids, and finally the acquisition of the images that might lead to KBO finds. But toward the end of the observing period, a broken coolant hose ended operations (and kept Subaru down for another three weeks). Spencer says the team left with 70 percent of what they were there for, in any case, and his laptop hard disk returned from the journey with data that will appear soon on Ice Hunters.

Image: The Subaru dome (left) is silhouetted by the Milky Way, as the telescope searches for KBOs. The search area is among the star clouds in the upper left of the image. (Credit: John Spencer).

Whether or not New Horizons gets to make that flyby of a distant Kuiper Belt object depends upon a number of things, among them NASA approval of an extended mission (it’s hard to see how this could be turned down given the rarity of our getting a spacecraft this far from the Sun), as well as the discovery of an appropriate KBO. The New Horizons team is looking for an object at least 50 kilometers across for a flyby and high resolution imagery, as well as spectroscopic investigations and study of possible moons or traces of an atmosphere. I can only echo Spencer’s invitation for those of you who haven’t yet done so to join the Ice Hunters search today. Remember, although we’ve found more than 1000 objects beyond Neptune’s orbit, it’s estimated that there may be half a million objects bigger than 30 kilometers across out there.



jkittle August 22, 2011 at 12:44

I view this as a critical mission on par with the Mars odyssey. It will start the process of evaluating (hopefully multiple) TNO’s . While mining metals in the asteroid belt is an old chestnut, using water , carbon dioxide ( and monoxide), dissolved minerals , ammonia and methane resources are REALLY exciting for us biologists. Because of ionizing radiation, the deeply frozen surface of these objects is not in chemical equilibrium. That is, there should be mixtures of compounds in the ice that together would provide a food and energy source for genetically tailored microorganisms. these coudl be scooped up and fed to bacterial factories to consume and grow. We have always thought about star ships and world ships as being constructed of metal and glass, and of course that is an important component, but plastics and carbon composites make really superior materials, even fiber reinforced Ice can be used in deep space as radiation shielding and structural( hull ) materials. Burrowing into these world can go to the core because of low gravity and low pressure from overburden. The surface and viable living space in burrows Dwarfs that of earth: To quote your article-
“Remember, although we’ve found more than 1000 objects beyond Neptune’s orbit, it’s estimated that there may be half a million objects bigger than 30 kilometers across out there.” do the surface area calculation. Each word over 30 Km in diameter one might support thousands of colonists .
This mission not only fills in a gap in our knowledge, tests exciting and reliable technology but also looks a bit like Apartment space hunting for my kids’ great grandchildren

andy August 22, 2011 at 18:29

While I’m a pessimist about the prospects for a viable space-faring civilisation much beyond Earth orbit for various reasons, the study of the trans-Neptunian objects is certainly a fascinating one in terms of the impact hazard. In the inner solar system you at least stand a chance of finding a hazardous object a long time before it hits, so in principle it is possible to do something about it. On the other hand, there are quite large, previously-unknown comets coming in from trans-Neptunian space all the time. Their trajectories get significantly modified by outgassing which reduces the accuracy of predictions of their motion, and they have been accelerated by a long fall inwards towards the Sun…

Laurel Kornfeld August 23, 2011 at 0:06

Ice Hunters is a terrific project, and I would love to see it expanded to a search not just for other KBO targets for New Horizons, but also for large, yet undiscovered KBOs. It’s amazing how technology provides anyone interested in doing research with opportunities that only a few years ago were limited to professional astronomers. I think most of the KBOs being searched for via Ice Hunters are not comets that come into the inner solar system, but KBOs that never come close to the Sun and are therefore not modified by outgassing.

Doug M. August 23, 2011 at 3:18

Current thinking is that cometary impacts on Earth are less common than asteroidal impacts by at least one order of magnitude, and maybe two.

They’re more destructive when they do occur, sure.

Doug M.

Doug M. August 23, 2011 at 3:19

Something I’ve never seen discussed: what happens if we don’t find a suitable body for a flyby?

Presumably NH just keeps rolling out to the heliopause, perhaps doing some science along the way in much the same manner as the Voyagers. But is there an actual mission plan?

Doug M.

jkittle August 23, 2011 at 11:19

re NH future mission
Even when ( and if) they do find a secondary target, it will not involve a large delta Vee change, so NH will continue on its voyage outward. Presumably there will be science to do, though unlike voyager, there has only been sporadic science attempted to this point- observing an asteroid during a fly by and making some significant observations of Jupiter and its moons during the gravity assist maneuver.
finding the secondary mission target now would help tweek the trajectory for the encounter with Pluto and bend the course in the right direction.

andy August 23, 2011 at 15:07

Another outer solar system related news, Mike Brown has pointed out on his blog that the current system where the IAU is the gatekeeper of admission to the dwarf planet class is far from ideal. He estimates that we know of around 390 objects that may be dwarf planets, of which the majority are unnamed.

Seems he has run with this idea in the latest press release regarding the object 2007 OR10, in which both 2007 OR10 and Quaoar are both referred to (sensibly enough in my opinion) as dwarf planets, despite the fact that neither has (yet?) been recognised as such by the IAU.

JohnQ August 23, 2011 at 16:57

In addition to my brilliant comments, I also have dumb questions on occasion. It strikes me as odd that Pluto has so many moons. I normally associate that with a large (true) planet, i.e. one that dominates it’s orbit. So is there something odd about Pluto, given that we know so little about it’s configuration and history?. Or am I missing something obvious that everyone knows, like just ordinary Pluto weirdness? I know, I could google it, but I was curious if anyone else had wondered about the large number of moons or if indeed there was anything worthy of notice? Thanks.

andy August 24, 2011 at 16:53

It strikes me as odd that Pluto has so many moons. I normally associate that with a large (true) planet, i.e. one that dominates it’s orbit.

Indeed, Mercury and Venus are well known for their extensive satellite systems ;)

Actually there are several known asteroids with satellites. The first confirmed discovery was the satellite (243) Ida, and since then there have been several more. There are also several known cases of asteroids with multiple moons, the first of these to be discovered was (87) Sylvia. In the Kuiper Belt, (136108) Haumea has two satellites, and (47171) 1999 TC36 is a triple system composed of a near-equal binary with a small satellite in circumbinary orbit.

So moon systems are certainly not diagnostic of planets!

Laurel Kornfeld August 26, 2011 at 0:04

JohnQ, the question of whether an object has to dominate its orbit to be a “true planet” is still a matter of debate. Since this was essentially an IAU decree, it cannot be separated from the controversy of the IAU acting as “gatekeepers” in the field. Many planetary scientists do view dwarf planets as “true” planets and wouldn’t be surprised if there are other dwarf planet systems out there with multiple moons–especially if we end up with something like close to 400 dwarf planets in the solar system. It makes much more sense to let discovery take its course than to have a self-selected group of “experts” issue decrees and then call those decrees science.

John Q August 27, 2011 at 14:32

>It makes much more sense to let discovery take its course than to have a self-selected group of “experts” issue decrees and then call those decrees science.

Thanks Laurel. I realize there are a lot of subtleties in this whole “dominating the orbit” thing. I also am in full agreement with you on letting “discovery take its course.” At one point, I believe that Pluto was viewed as being an escaped moon of Neptune after some kind of planetary dust up, possibly with Triton, but I believe that notion is no longer au courant. Anyway, I was so taken by the quantity and complexity of Pluto’s moons that I wondered if there might be a very intersting anomoly here. I remain persuaded that such is indeed the case and that Pluto, whatever it is, has a lot of surprises in store for us.

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