≡ Menu

Notes & Queries 2/23/09

Prioritizing the Outer System

Europa or Titan? Jupiter or Saturn? NASA and the European Space Agency, faced with the dilemma of choosing between competing missions, apparently settled on both, with the Europa Jupiter System Mission likely to be implemented first. Here we’re talking about two robotic orbiters, launched on separate spacecraft in 2020, with arrival in Jupiter space in 2026. The two orbiters will orbit Europa and Ganymede respectively, while the later Titan Saturn System Mission would include a NASA orbiter and an ESA lander and research balloon. Both missions thus move forward for further study.

I note all this in the context of what will surely be ever increasing interest in Europa following the publication of Richard Greenberg’s Unmasking Europa: The Search for Life on Jupiter’s Ocean Moon. I’ll be talking to Greenberg tomorrow and reporting on our conversation soon, but I do want to quote him on a particular point right away, relevant as it is to mission planning:

“…when a spacecraft returns tens of thousands of or hundreds of thousands of images, most of that data is stored away and never studied in detail — or studied at all. Occasionally a graduate student or other persistent scholar might revisit old data as part of a research project, but there is relatively little funding or motivation for digging through archived material. And the older the data get, the more difficult it is to retrieve and understand. Instead, the big money and attention are lavished on the fresh new images from the latest mission.

Why is this a problem? Because we design new missions based on our understanding of the targets we plan to study. And if we misinterpret our results — Greenberg convincingly argues that this has happened with our analyses of the thickness of Europa’s ice — then we might design missions down the road that don’t take advantage of the real situation on the surface. We need new missions, of course, but we shouldn’t forget the vast backlog of data that can provide many of the answers we need about Europa through patient analysis long before the Europa Jupiter System Mission ever lifts off.

And looking beyond this next Jupiter mission, we need to find out for sure how thick the surface is before we design an even later mission around the idea of drilling through tens of kilometers of ice. Greenberg again, from Unmasking Europa:

If we confirm that we might put a lander at just the right place next to an active crack so that within a few hours fresh sea water will slosh to the surface, or that frozen sea life are spread over the surface by the variety of ways that oceanic water reaches the surface, then we would design very different mission strategies than if we believe that everything interesting is sealed off more than 20 km down.

We’re in a new era of science, one in which data accumulate so quickly that we often don’t have the funding or the time to do the kind of detailed analysis necessary. This is a challenge for any scientist, but especially those planning missions to targets as provocative as these. Add to this the potential for data loss as we continually upgrade and change data formats and hardware and you can understand why managing digital resources is going to be a key aspect of future planetary exploration.

Changes to Centauri Dreams

Now and then when you log on to Centauri Dreams in the next few weeks, don’t be surprised to find yourself looking at unexpected formatting. I’m working on various software changes behind the scenes that will give me more flexibility in posting and managing the information flow. And because I am anything but a skilled coder, you can expect the occasional mistake as I tweak the options. Things will eventually return to normal under a slightly revised format, but bear with me as I leap into the unknown.

Several of you have noticed the favicon the site has added. A ‘favicon’ is the little image you can see in your browser’s address bar when Centauri Dreams is loaded, immediately to the left of the Web address. Many sites these days have them, but reader Piotr Mazik noticed I didn’t. Actually, I had tried to implement one, but ham-handedly had created the image in the wrong format. So Piotr was kind enough to make one himself and pass it along. In such ways, large and small, I benefit from the readership here every day, and send thanks to Piotr and all who have made suggestions and come up with helpful tips related to keeping Centauri Dreams online.

Space, Propulsion and Energy Forum in Huntsville

The Space, Propulsion and Energy Sciences International Forum (SPESIF 2009) kicks off tomorrow in Huntsville at the Von Braun Center and runs through the 26th. Although I can’t be there, I’ll be interested in reading a transcript of Les Johnson’s report on interstellar propulsion research, which leads off the meeting. Johnson (NASA MSFC) has been looking at interstellar options for a long time, having once served as the head of the provocatively titled Interstellar Propulsion Project, which NASA later folded into the In-Space Propulsion Program at the Alabama facility.

Now deputy manager for the Advanced Concepts Office at MSFC (and author, with Greg Matloff and Giovanni Vulpetti, of the excellent Solar Sails), Johnson will also be addressing solar sail options. Have a look at the site, where numerous abstracts and preprints are made available. Among other presentations, I was attracted by Gerald Jackson’s session on antimatter. Jackson (Hbar Technologies, Chicago) has been working on antimatter harvesting in space and, along with Steve Howe, has been a proponent of the hybrid antimatter/fission sail concept we’ve discussed earlier here on Centauri Dreams. His study for NIAC on space-based antimatter retrieval is still available at the NIAC site, despite that organization’s demise, and a preprint of his SPESIF talk is also online.

As a former medievalist with an interest in Icelandic studies, I’m particularly looking forward to reading “Space Exploration and the Greenland Norse; A comparative Study on the Application of Technology for Exploration,” by Theodore Swanson (NASA GSFC). The Norse settlements in Greenland in the Middle Ages were never robust and eventually failed, with interesting analogies to our movement into the far more hostile environment of space. Such studies remind us of the contribution cross-disciplinary studies can have as we contemplate the potential long-term spread of our species off-planet (preprint here). Thanks to Paul Titze for updates on this conference.

Space Survey Goes Online

Space Expectations is an online survey by the International Academy of Astronautics whose goal is to “Enable a merging of the technological/scientific goals of space activities within society’s expectations. This will lead to programs that are supported by the public, generate more interests and have fewer disconnects with society.” Every completed survey helps as we try to build better bridges between the space community and the public, hoping to muster support for continuing exploration in tough economic times. Your participation is welcome.

Comments on this entry are closed.

  • george scaglione February 23, 2009, 11:55

    hello all, the space propulsion and energy sciences forum mentioned above looks good! the perfect sort of conference for people like us here!! i really hope we will discuss and hear more about that here! all the best my friends, george

  • bill seney February 23, 2009, 17:42

    When I atempt to access the SPESIF preprints I am prompted for a password and username.

  • Administrator February 23, 2009, 19:04

    Bill, some of the preprints seem to be behind university or other firewalls. Others are not — I’ve downloaded several. So you’ll have to pick and choose. Seems silly to have preprints behind a firewall with the conference only hours away, and I hope there aren’t too many of these.

  • James M. Essig February 23, 2009, 22:56

    Hi Folks;

    An interesting take on Steve Howe’s antimatter sail would entail a sal that at relativistic speed could assimulate ions, atoms, and molecules from the interstellar medium,

    The sail as such would somehow be composed of elements that would grow in atomic mass and number to the point where the new atomic species would be processed in route and fashioned into additional sails wherein the new sail material would be catalyzed by additional antimatter carried onbaord the craft and/or collected in route. The new sails could capture additional nuclei, atoms, and molecules and the process could repeat itself.

    As the ship speed grew to significantly greater fractions of C, the sail could be; made of thicker material, electically charged to slow the velocity of the incomming particles, or perhaps be composed of a linear series of sails wherein if the first sail did not capture a given particle, one of the backward located sails would be likely to.

    Efficient nano tech self-assembly might be an excellent way to re-manufacture the sail material as well as a way to efficiently extract optimal atom species from the sail material undergoing processing for reintegration into new sail material.

    It would help if the collisional kinetic energy of the inbound interstellar matter could be appropriately recycled to power some sort of electrodynamic propulsion system.

    Either way, the antimatter sail is a great idea and Steve Howe is a brilliant visionary for comming up with the concept of the antimatter sail.



  • george scaglione February 24, 2009, 17:00

    i agree what is the point of putting these hopefully interesting articles on line at all!? if you are going to make them hard to get too!!?? yes bill i encountered the same problem you did! i’d like however to know a little more about the sails jim discusses above although i have to admit that i have never been much on the concept of using “sails” in space.one of my favorite all time special effects in the movies is watching a starship go into warp drive.kind of gives you a hint on the way i think about the best way to get around in the galaxy ,does it not? still i hope i will hear more about this conference soon.have a great day guys your friend george ps as i typed have a great day guys it occured to me that it is a shame that i do not see many women around this area if any at all.usually if i see even one she voices her opinion and pretty much even when answered that is about as far as it goes.any ideas on that fellas? :( g

  • Paul Titze February 24, 2009, 22:46

    Those looking to read the SPESIF papers:

    – You can either goto AIP:

    – Or you can go through the abstracts you’re interested in:

    and Email the author requesting the paper. Cross reference with the AIP table of contents to help you sort out the abstracts. Their contact address is in their abstracts. Most are more than happy to send you a copy.

    Cheers, Paul.

  • ljk March 13, 2009, 9:55
  • ljk April 16, 2009, 10:52

    Europa Jupiter System Mission Colloquium

    Apr. 14, 2009 | 09:08 PDT | 16:08 UTC

    by Ted Stryk

    On April 9, the University of Tennessee’s Earth and Planetary Sciences department hosted a colloquium led by Bob Pappalardo of JPL to discuss the recently selected Europa Jupiter System Mission (EJSM).

    Pappalardo began by discussing our current, post-Galileo understanding of Europa. It is thought that the current ice shell is 60-100 million years old. Due to a small amount of torque applied to the Jupiter-facing side at its closest point in its orbit [caused by tidal forces from Jupiter], the outer shell rotates at a slightly asynchronous rate (a ballpark number given was one extra rotation for every 10^6 orbits).

    This conclusion is based on observations of the positions and orientations of linear features on Europa; the stresses on the ice crust that made those linear features seem consistent with Europa having picked up about a third of a rotation since the ice shell formed.

    Full article and images here: