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Weekend Reading from Triton to Kentucky

The Kentucky space program may get back to the Moon before NASA or the Chinese. If that sounds cryptic, do visit the latest Carnival of Space, held on Wayne Hall’s KySat Online site, which supports this innovative and student-led program to get the educational system into the business of designing, building, and operating small satellites. Wayne writes:

The very first project of this ambitious enterprise is a cooperative, student-led effort to design, build and fly a CubeSat that kids from the eastern mountains to the western Mississippi river shore can figuratively reach out and touch from classrooms all over the state. The first of many planned efforts, it will rocket to orbit sometime late this year or early next.

Good fortune accompany the attempt! I hope many states are watching what Kentucky is doing, an educational activity that spreads interest and enthusiasm for space projects to the next generation of scientists.

As to the Carnival itself, I normally choose one post of particular interest to Centauri Dreams readers, and this week I send you to Colony World‘s musings on Triton, Neptune’s largest moon, famous for the retrograde orbit that seems to argue that it is a captured object. Darnell Clayton is intrigued by the proximity of Neptune’s helium-3, and the possibilities for future human settlements in this remote part of the Solar System. Just how much might Triton be worth to us?

I also want to note Adam Crowl’s comment about Triton in a recent post, which notes a paper by Paul Schenk and Kevin Zahnle that implies even more melting of the moon’s crust than we see around Enceladus’ southern pole. Is a sub-surface ocean possibly bursting through in cryovolcanic events, as Adam speculates? So far we have all too little data from spacecraft, but the Voyager imagery tells us how rich a Neptune orbiter mission would be. Fraser Cain at Universe Today offers a nice chart of the known trans-Neptunian objects in the context of a backgrounder on how we have come to define the word ‘planet.’ Useful stuff in these confusing times, and helpful to those of us who speculate about the discoveries yet to be made in the Edgeworth/Kuiper belt.

Although not in this week’s Carnival (well, for that matter, neither is Adam’s Triton post, but bear with me as I collate various things I’ve been meaning to write about), Brian Wang looks at an electric solar sail concept developed at the Finnish Meteorological Institute and the plans for a test mission. This one uses an electron gun to charge long metallic tethers, riding not the momentum imparted by photons but the solar wind, an interesting variation on existing magsail concepts.

Comments on this entry are closed.

  • Colin Weaver April 19, 2008, 21:44

    On current trends, I’d wager that the next person on the moon will be Chinese or Indian. If the next moon landing is by a westerner, they will be flying something cooked up by Bert Rutan and funded by Paul Allen & Richard Branson :-)

  • James M. Essig April 21, 2008, 1:19

    Hi Paul and Colin Weaver;


    Good Comments!

    It is interesting that China and India both want to send humans to the Moon in a decade or decade in a half. If we within the U.S. want to beat them, we had better redouble our efforts. Being bogged down in the War in Iraq and in Afganistan hasn’t helped us either.

    Speaking of Bert Rutan and Paul Allen & Richard Branson, I hear that even the U.S. Military/Department of Defense is becomming strongly interested in what Bert Rutan is up to as well as the other space tourism companies. This should not suprise me since aerospace flight changing paradinms can come from companies with researchers who are not stymied in the old ways of thinking. Heck, if there is any truth about the Aerorae Spy Plane legend, some of the stuff that is being worked on by these space tourism companies at least in principle kicks butt on the alledged spy plane.


    An electric solar sail is potentially a great way to reach the speed of solar wind at about 1,000 Kilometers/sec. I can imagine very large space arks being launched throughout our stellar nieghboorhood powered by such a system. At 0.33 percent C, they would take on the order of a thousand years to get to the Centuari System, and about 20 thousand years to get to any of the many hundreds of stars within a 60 light year radius of Earth. However, the slow travel speeds would mitigate the need for super heavy shielding from debris and would mitigate the need for otherwise much more rigorous and advanced collsion avoidance technology such as sensors, laser and particle beam based blasters, perhaps nuclear warheads, and less rigorous evasive manuevers technology.



  • David April 21, 2008, 1:56


    You may well be correct, I heard that the Chinese are also thinking about a trip to visit a near earth asteroid.

  • Pointless Geometry April 21, 2008, 9:04

    It could well be the Finns if that Electric Solar Sail develops to fruition – fingers crossed. And it won’t be the just the Moon they’ll be shooting for.

  • Bob Shaw April 24, 2008, 9:35

    Triton could, because of it’s strange orbit, turn out to not only be rather easier for us to visit than most other outer planetary satellites, but may also provide a unique repository for debris from the depths of space. It’s retrograde orbit and tidal-lock could create swathes of landscape where material may come to rest at very much lower speeds than we might normally expect. Triton might be a Rosetta Stone, with even fragile extrasolar samples making it to the ground in one piece, suffering less damage than even a cometary capture would allow

    Bob Shaw

  • ljk September 26, 2009, 10:29

    Secular evolution of a satellite by tidal effect. Application to Triton

    Authors: Alexandre C. M. Correia

    (Submitted on 23 Sep 2009)

    Abstract: Some of the satellites in the Solar System, including the Moon, appear to have been captured from heliocentric orbits at some point in their past, and then have evolved to the present configurations. The exact process of how this trapping occurred is unknown, but the dissociation of a planetesimal binary in the gravitational field of the planet, gas drag, or a massive collision seem to be the best candidates. However, all these mechanisms leave the satellites in elliptical orbits that need to be damped to the present almost circular ones.

    Here we give a complete description of the secular tidal evolution of a satellite just after entering a bounding state with the planet. In particular, we take into account the spin evolution of the satellite, which has often been assumed synchronous in previous studies.

    We apply our model to Triton and successfully explain some geophysical properties of this satellite, as well as the main dynamical features observed for the Neptunian system.

    Comments: 4 pages, 1 figure

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

    Journal reference: Astrophysical Journal Letters 704 (2009) L1-L4

    DOI: 10.1088/0004-637X/704/1/L1

    Cite as: arXiv:0909.4210v1 [astro-ph.EP]

    Submission history

    From: Alexandre Correia [view email]

    [v1] Wed, 23 Sep 2009 13:33:57 GMT (395kb)