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Waiting Out New Horizons

The outer Solar System has always been something of an obsession for me, to the point where as a kid, I used to haunt the libraries looking for books on planetary science. Absurdly, I had the notion that even though little was known about places like Triton and Pluto, I might just stumble upon the one book that had details known to no one else. So I would work my way through the shelf, finding the odd speculation here, the small insight there, but it wouldn’t be until Voyager’s 1989 Neptune flyby that some of these places began to take on actual shape for all of us.

All the Myriad Ways

And then there was Larry Niven’s ‘Wait It Out,’ a short story from the Known Space universe that was originally published in 1968, in a wonderful collection called All the Myriad Ways. Here a team of astronauts on the surface of Pluto is marooned and the narrator, after his comrade has died, removes his helmet, freezing to death so quickly that his brain becomes a superconductor, so that a strange form of consciousness persists. The things you read when you’re young stick with you, and the strange awareness of the frozen narrator still comes to mind when I think about New Horizons and the things it will find at Pluto/Charon in just a few more years.

I can’t resist a brief quote from Niven’s story:

A superconductor is what I am. Sunlight raises the temperature too high, switching me off like a damned machine at every dawn. But at night my nervous system becomes a superconductor. Currents flow; thoughts flow; sensations flow. Sluggishly. The one hundred and fifty-three hours of Pluto’s rotation flash by in what feels like fifteen minutes. At that rate I can wait it out.

I stand as a statue and a viewpoint. Now wonder I can’t get emotional about anything. Water is a rock here, and my glands are contoured ice within me. But I feel sensations: The pull of gravity, the pain in my ears, the tug of vacuum over every square inch of my body. The vacuum will not boil my blood. But the tensions are frozen into the ice of me, and my nerves tell me so. I feel the wind whistling from my lips, like an exhalation of cigarette smoke.

Getting our protagonist rescued by a ship from Earth may be the least of his problems, for he’ll have to be thawed out to survive. But Niven covers that my noting that ‘half a million corpses lie frozen in vaults surrounded by liquid nitrogen’ back on Earth. In other words, they’re working on it.

Neptune and the Kuiper Belt

But back to reality. It’s been the week of the American Astronomical Society’s Division of Planetary Sciences conference in Pasadena, which is always good for an outer planet fix that puts my old library method to shame. Several interesting items come to mind not just about Pluto but other objects including Neptune, which has been studied in terms of its effects on binary objects in the Kuiper Belt. This work, done by Alex Parker and J.J. Kavelaars (Herzberg Institute of Astrophysics) traded on the fact that binaries can be affected by their environment, and therefore become a testbed that through computer simulations can tell us something about the Kuiper Belt’s past.

Have a look at the image to see the process at work. Here, Neptune exerts tidal forces that disrupt the binary. According to the simulations, many binary systems should have been destroyed by this jostling, too many to explain the stability of the Kuiper Belt we see today. That has ramifications on earlier Kuiper Belt theories.

Image: The process that destroys binaries during close encounters. Credit: J.J. Kavelaars.

At stake is what astronomers call the ‘Classic Cold Kuiper Belt,’ one explanation for which is that it formed during numerous interactions with Neptune. The new work seems to rule out some aspects of that theory, according to Parker, who says: “These binaries with slow, wide orbits are a hallmark of the Cold Classical Kuiper Belt, and they would not be there today if the members of this part of the Kuiper Belt were ever hassled by Neptune in the past.” The implication is that the Kuiper Belt formed more or less where it is now and has remained undisturbed over the age of the system.

And it’s not just the influence of an outer planet but also the site of Kuiper Belt formation that’s at stake. One proposed model for Neptune involvement has been that the objects of the Classic Cold Kuiper Belt would have formed closer to the Sun than their present distances, and then been scattered outwards through the Neptune interactions. The binary studies argue against that interpretation:

…these results would require more primordial binaries than even a binary fraction of 100% would allow, suggesting that wide binaries such as 2001 QW322 were not subjected to a period of close encounters with Neptune. This implies that a component of the Cold Classical Kuiper Belt was not emplaced by scattering from lower heliocentric orbits, but either had to form in situ or be implanted by a gentler mechanism in order to preserve its population of wide binaries.

Exploring the Surfaces of KBOs

The DPS sessions also produced interesting dwarf planet news, in this case about Eris, the largest of these objects currently known. Here a team led by Stephen Tegler (Northern Arizona University) has gone to work studying the remote surface of Eris, growing ice samples of methane, nitrogen, argon, methane-nitrogen and methane-argon mixtures in a vacuum chamber at the -235 degrees Celsius temperature of Eris (and if anything can turn a person’s brain into a superconductor, the temperature of the surface of Eris should do the trick).

The method was, having produced these ices, to pass light through the samples to study the ‘chemical fingerprints’ of molecules and atoms, which were then compared to telescopic observations not only of Eris but Pluto. David Cornelison (Missouri State) explains the result:

“By combining the astronomical data and laboratory data, we found about 90 percent of Eris’s icy surface is made up of nitrogen ice and about 10 percent is made up of methane ice, which is not all that different from Pluto.”

Not surprising, but a needed measurement as we study the properties of the larger Kuiper Belt objects to understand how planets formed in these distant regions. Northern Arizona University’s ice lab should prove to be a helpful place as we carry on this work, helping us understand the processes at work on KBO surfaces. And all of this should play usefully into preparations for the New Horizons encounter, on course for a 2015 flyby to remember.

The paper is Tegler et al., “Methane and Nitrogen Abundances on Eris and Pluto,” submitted to The Astrophysical Journal (abstract). The Kuiper Belt paper is Parker and Kavelaars, “Destruction of Binary Minor Planets During Neptune Scattering,” accepted by Astrophysical Journal Letters (preprint).

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  • Greg October 8, 2010, 15:41

    I’m a huge fan of Niven’s and remember reading ‘Wait it out’ years ago. Just to let other fan’s know, Niven has another book coming out the 12’th “Betrayer of Worlds”. Thanks Paul for that little reminder of good Sci-Fi stories.

  • Adam October 8, 2010, 20:34

    I think I first read “Wait it Out” in about 1985, and I ended up wondering why a Pluto mission hadn’t been organised in the 17 years since Niven published the story. Expectations about space-travel fell a long way in just 2 decades.

    Of course thermophysics realities mean the freezing won’t happen as quick as Niven describes. A live body produces about 100 W and at 310 K in a 5 K background loses about ~250 W, thus implying a significant time of freezing. If he had dove into a pool of liquid helium it wouldn’t have been liquid for long, but might have sped the process up. I doubt his skin would retain any sensations from the evaporative cooling and freezing that would’ve rapidly dulled his nerves.

    FYI the total heat content from 310 K to 5 K is about 1.1 MJ/kg for a human body (mostly water) and massing 70 kg it’s about 77 MJ total. Going to take a few days at least to freeze solid. Would be unconscious within a few minutes, but would be unpleasant.

  • Procyan October 8, 2010, 20:53

    http://homepage.mac.com/joebergeron/wait.htm

    I always went back to the libraries hoping for a new text to update the woefully limited descriptions of the planets. You’ve reminded me of that horrible impatience to get on with it. Always the same old worn texts, reread until nothing more could be gleaned. Torture!

    I wanted to plant lichens on Mars. Whats going on under those Venusian clouds? Steady state made sense, BB was a term of derision. At least there was great sci fi on offer, only fiction could ease the burning need. More!

    My life has since been enriched by scientific enquiry many fold. We have come far to learn so much in a lifetime.

    I am fortunate to have lived this long but t’will never be long enough. More please, i would like more. Hmmm, just lift this helmet you say?

  • Joy October 8, 2010, 23:55

    I had the pleasure of meeting Clyde Tombaugh and his wife at his modest home on the way to watch a DC-X flight at White Sands in July 1995. So I have nothing but best wishes and fond feelings for New Horizons. And yet…

    What most comes to mind is that Pioneer 10 flyby probe (hydrazine steered, powered by RTG) was launched on her solar escape trajectory in 1972 on an Atlas/Centaur. The New Horizons flyby probe (hydrazine steered, powered by RTG) was launched in 2006 on an Atlas/Centaur.

    Ok, I will admit that New Horizons has far more advanced instruments than Pioneer 10. But still… The big picture is of 34 years – a third of a century – with no progress in propulsion. Not at all what the prophets of exponential progress expected!

    My heart is much more gladdened by the Dawn probe, which will orbit first Vesta and then Ceres using an ion drive. Likewise, the Japanese Ikaros solar sail demonstration was brilliant, as are their plans for a follow on mission with a larger sail. This feels more like actual innovation.

  • Duncan Ivry October 9, 2010, 19:31

    Joy: “34 years … with no progress in propulsion”

    There has been considerable progress in ion propulsion.

    Examples:
    – Hayabusa, launched in 2003, did a rendezvous with asteroid 25143 Itokawa, collected samples, and returned to Earth recently.
    – Smart 1, launched in 2003, did a controlled collision on the Moon’s surface.
    – Dawn, launched in 2007, explores the asteroid Vesta and the dwarf planet Ceres, mission duration five years (you, Joy, mentioned it).
    – GOCE, Gravity Field and Steady-State Ocean Circulation Explorer, launched in 2009, resists air-drag in low earth orbit, mission continues.

  • Joy October 9, 2010, 20:51

    @Duncan

    I am quite happy about the adoption of ion drive on (*some) current probes. [*Conspicuously absent on the 2004 launches of Rosetta and Messenger]

    However I recall the spirit of 1969 (when Pioneer 10 was approved) very well. At that time, human missions to Mars were hoped to occur in the 1980s. Arthur C. Clarke’s 2001 was (other than the aliens) thought to be an accurate extrapolation of current trends by many. The percentage of space enthusiasts in 1969 who would have expected a 21st century Pluto probe to be launched by the same vehicle as Pioneer 10 was probably in the low single digits. As late as 1986, the 1 megawatt nuclear reactor powered TAU mission was given serious consideration by JPL http://www.daviddarling.info/encyclopedia/T/TAU.html

    My point being that our dreams have been drastically downsized and postponed, and almost no one (in the space enthusiast community) saw it coming. Space travel was supposed to become cheaper and more routine, not increasingly difficult (NASA had to struggle to scrape together enough plutonium 238 for a RTG for New Horizons) and unaffordable.

    What are we wrong about now?

  • jdk October 9, 2010, 21:36

    First no one seems to mention space tethers for earth orbit boosts, Tethers would work even better for mars, where they may help overcome the VERY severe problem with landing multi- ton payloads in the thin atmosphere.

    Seems to me we are all waiting for an energy source. Hydrogen fusion is well within our physics but not our engineering. The ITER and NIF projects are bureaucratic nightmares ( they make NASA look efficient!) You may have a better chance or launching the astrodome that an astro-tokamak!

    the Z pinch method is the real leader in my mind but ( the public effort) is being held up over concerns about weapons proliferation.- it is not unreasonable to extrapolate to a brief case sized thermonuclear device that requires no fission.. Sorry to say the Z-pinch fusion source may not be all that helpful in space- you need a pretty big mass and large sized chamber to contain the sub-kiloton blast

    given a steady energy source Ion drives will let us explore out to the Kuiper belt, and maybe to the Oort cloud

    jdk

  • Duncan Ivry October 10, 2010, 14:26

    @Joy

    I’m able to share your feelings. But in 1969 I was an adolescent, and now I’m a grownup. I stopped whining long ago, and I do what grownups do: get a handle on reality. And reality is (e.g.): We are in a golden age of astronomy; we know, that there are a lot of planets around distant stars. This dream has come true already. You ask what we are wrong about now? Irrelevant!

  • Eniac October 10, 2010, 20:37

    @jdk: Fusion is not that much of an improvement over fission, really. In fact, in terms of power/kg fission is probably far superior because it does not require magnets. So, I question the observation that “we are waiting for an energy source”, we have a perfectly good option. I think a large part of the problem is that NASA is worried nuclear reactors in space are not politically correct, and they may well be right about that. It is a sad state of affairs.

    There is some hope that our terrestrial energy problems will force us to make friends with nuclear power again, which should help lift the current irrational inhibitions in the space propulsion field.