≡ Menu

FOCAL: A Renewed Call for Papers

Every few weekends as we move toward the March 5 deadline for submission of abstracts to the next International Astronautical Congress, I’ll re-run this call for papers that I originally published in December. The Tau Zero Foundation hopes to energize discussion of FOCAL in the astronautical community and create a growing set of papers analyzing aspects of the mission from propulsion to communications, leading to a formal mission proposal. We hope anyone interested in furthering this work at the coming IAC in Prague will consider submitting a paper.

The Tau Zero Foundation is announcing a call for papers related to the FOCAL mission. The venue: The 61st International Astronautical Congress in Prague, which convenes on the 27th of September, 2010 and runs to October 1. Specifically, we are looking for papers for session D4.2, “Interstellar Precursor Missions,” whose focus is “…missions that significantly expand science — using existing and emerging power and propulsion technologies.”

Long-time Centauri Dreams readers are well aware of Claudio Maccone’s FOCAL concept, a mission to the Sun’s gravitational lens at 550 AU and beyond. FOCAL would make possible studies of astronomical objects at unprecedented magnifications. The electromagnetic radiation from an object occulted by the Sun at 550 AU (i.e., on the other side of the Sun from the spacecraft), would be amplified by 108. Moreover, whereas with an optical lens light diverges after the focus, light focused by the Sun’s gravitational lens stays fixed along the focal axis. Every point along the straight trajectory beyond 550 AU remains a focal point for any vehicle we put on this trajectory.

Imagine, then, two possible FOCAL mission targets. The first option would be to launch the probe toward the heliopause in the place where it is closest to the Sun, the direction of the incoming interstellar wind. This would allow useful studies of the heliosphere itself, but the deeper goal would be to reach 763 AU, the place where the cosmic microwave background will be focused by the Sun’s gravitational lens upon the spacecraft. As Maccone has shown, detecting lower frequencies pushes the focus further from the Sun — the focal distance, in other words, changes as a result of frequency.

We’ve learned how valuable information about the CMB is to cosmologists. Now imagine the result of examining the CMB with the vast magnifications possible through a FOCAL probe. But a second choice is also available. FOCAL could be optimized for close study of the Alpha Centauri stars, especially if current efforts pay off and we do find interesting planets around Centauri A or B. Centauri demands a different kind of mission because it is far from the ecliptic. The flight path is problematic because the Centauri stars are so close, requiring ion propulsion to achieve the necessary spiral trajectory.

Addendum: So many readers have mentioned Dr. Maccone’s recent SETI Institute lecture that I want to go ahead and link to it now, although I was planning a separate piece on it next week. When I met with Claudio recently in Austin, he was getting ready to leave for the West Coast to make this presentation before concluding his US trip and heading back to Italy. What a pleasure it was to talk to him at leisure about FOCAL.

But all of these are matters that now need to be taken to the next step at the International Astronautical Congress, where they will gain further visibility in the scientific and industrial community. Papers are solicited on the propulsion problem — is a solar sail optimal? Nuclear-electric? Perhaps VASIMR? We also hope for submissions on the scientific return from a FOCAL mission, on telecommunications technologies, on computing requirements, and perhaps on the social and cultural value of a concept that would take human technologies further from the Sun than any previous missions.

focal_cover

Image: The FOCAL mission as currently envisioned by Claudio Maccone. The image is taken from the cover of his book Deep Space Flight and Communications: Exploiting the Sun as a Gravitational Lens (Springer/Praxis, 2009), and shows two 12-meter antennae operating through a tether which is gradually released, allowing a field of view much larger than that offered by a single antenna. Credit: Claudio Maccone/Springer.

The preliminary program for the Prague IAC has already been posted. The deadline for submitting abstracts to the Congress is 5 March 2010. Let me quote from the IAC documentation on what the criteria for selection will be:

Paper selection

Submitted abstracts will be evaluated by the Session Chairs on the basis of technical quality. Any relevance to the Congress main theme of ‘Space for human benefit and exploration’ will be considered as an advantage.

The criteria for the selection will be defined according to the following specifications:

* Abstracts should specify: purpose, methodology, results and conclusions.

* Abstracts should indicate that substantive technical and/or programmatic content is included

* Abstracts should clearly indicate that the material is new and original; explain why and how.

* Prospective authors should certify that the paper was not presented at a previous meeting and that financing and attendance of an author at the respective IAC at Prague to present the paper is assured.

Full information about the meeting and the submission process is available through the official Call for Papers & Registration of Interest.

tzf_img_post

Comments on this entry are closed.

  • andy January 9, 2010, 12:48

    I wonder how well Epsilon Eridani would work as a target: it is closer to the ecliptic than Alpha Centauri and there’s definite evidence of a fairly complex planetary system there, involving multiple debris belts and one or more giant planets in long-period orbits.

  • Administrator January 9, 2010, 16:56

    Exactly so. Epsilon Eridani keeps you much closer to the ecliptic, avoiding that huge ‘bend’ that needs to take place in the trajectory to use FOCAL on Alpha Centauri. That has significant propulsion ramifications. Ralph McNutt has considered this in his own work on interstellar probes and once told me in an interview that he was surprised how much easier a target Epsilon Eridani was.

  • Tulse January 9, 2010, 18:09

    I wonder how well Epsilon Eridani would work as a target: it is closer to the ecliptic than Alpha Centauri and there’s definite evidence of a fairly complex planetary system there

    And if the resolution is good enough, we might see activity on Vulcan!

  • daniel January 9, 2010, 19:22

    it is possible use the FOCAL to take pictures or a least detect of extragalactic planets on SMC, LMC or andromeda galaxy?

    anybody knows?

  • Eniac January 10, 2010, 1:54

    Paul: If, as Dr. Maccone has said and as I believe, any FOCAL mission must have a final close solar flyby, the ecliptic should not have much impact at all on the feasibility of a trajectory. The second to last flyby would be of a gas giant, resulting in a dive towards the sun that could be easily directed, by very small perturbations before the gas giant encounter, above or below the ecliptic. The result would be that the ecliptic would play a very minor role in the choice of trajectories. Where is this reasoning wrong?

    As I understand, the Voyagers are leaving well outside of the ecliptic because it was easy to do, for similar reasons.

  • Administrator January 10, 2010, 9:14

    Eniac, let me ask Claudio to comment on this — I remember a long discussion about it when I saw him in Austin.

  • daniel January 10, 2010, 10:55

    Tulse said:
    “I wonder how well Epsilon Eridani would work as a target: it is closer to the ecliptic than Alpha Centauri and there’s definite evidence of a fairly complex planetary system there

    And if the resolution is good enough, we might see activity on Vulcan!”

    1_ the space.com made a mistake here the Vulcan of star trek from 40 Eridani (Omicron 2 Eridani) this star it’s a triple system at 16.6 light years http://en.wikipedia.org/wiki/40_Eridani

    and about the science fiction Vulcan planet that orbit around 40 Eridani A see at: http://en.wikipedia.org/wiki/Vulcan_(Star_Trek)

    2_ Epsilon Eridani it’s too young star (between 500 at 850 million years old) to develop intelligent life forms(exepct if there a alien colony there,which is very unlikely,and ever if exist such colony the mission probabily not detect the colony ) it’s not a good place for FOCAL mission look for life…

    http://en.wikipedia.org/wiki/Epsilon_Eridani

  • Tulse January 10, 2010, 13:00

    it is possible use the FOCAL to take pictures or a least detect of extragalactic planets on SMC, LMC or andromeda galaxy?

    I presume that a FOCAL mission could be used to detect planets via transiting, radial velocity, and even microlensing, just like current telescopes. Whether the increased magnification of FOCAL would make those methods usable for extragalactic planet detection is another question.

    I also suppose that, even if it is possible to do planet detection, it may not be practical because (I presume) FOCAL has a very narrow visual field — it sees a very small part of the sky, and so wouldn’t be useful for planet discovery, but only for further study of already-known objects. Does anyone know if that is accurate?

  • Eniac January 10, 2010, 15:57

    A few more thoughts on FOCAL:

    Has anyone asked a cosmologist whether observing the CMB at many orders of magnitude resolution in a very small field of view would be expected to produce exciting new insights? As I understand much work has focussed on resolving small intensity variations over the whole sky, which FOCAL may not be very helpful with. In any events, cosmologists must be licking their chops at the thought of observing extremely far away objects from the beginnings of the universe with this kind of resolution, at any wavelength. These objects might be a little easier than nearby stars, because they do not move.

    For exoplanets, I think the main use would be imaging their surfaces after they have been found. That , to me, is the most spectacular application I can think of. I don’t see good use of FOCAL in trying to find new planets. Except, perhaps, to detect additional smaller planets in a system already picked for observation for other reasons. For example, a star with a previously known occulting planet would be relatively easy to scan for more planets, as you know you are observing the system edge on and only need to scan one-dimensionally along its ecliptic.

    Imaging stellar surfaces at high resolution would probably draw a lot of interest from the groups now observing the sun, currently the only star close enough to observe the surface of at any level of detail.

    Neighboring galaxies should be another exciting target for those studying galaxies, it would be possible to resolve stars and galactic nuclei to a level close to what we can currently only do in our own galaxy. Perhaps even better, because we could be observing from a better vantage point outside of the disk.

  • kelvin January 11, 2010, 12:20

    here is an interesting thought: Presumably our galaxy also has a gravitational lensing point and if so where is it located and how far by how much could be magnified, assuming you could get there?

  • Mike Prather January 11, 2010, 17:46

    I’m curious: are Jupiter or our other jovian planets massive enough to provide significant gravitational lensing? If so, wouldn’t that make a mission within our own solar system a bit less propulsion and resource intensive, especially for targets near the ecliptic? I would also think occulting would be an easier prospect on a darker target than the Sun. Just a thought.

  • andy January 11, 2010, 19:38

    Mike Prather: gravitational deflection of light is given by the formula θ=4GM/(c²b) where b is closest approach. Then apply trigonometry to get minimum distance of focus.

    Using M = solar mass, b = solar radius, then distance is about 550 AU.
    Using M = Jupiter mass, b = Jupiter radius, distance is about 6000 AU.

    Oh well.

  • Ric Capucho January 12, 2010, 9:51

    Mike,

    I also got the logic of lensing the wrong way around, so you’re not alone. :-)

    Ric

  • andy January 12, 2010, 14:49

    Epsilon Eridani it’s too young star (between 500 at 850 million years old) to develop intelligent life forms(exepct if there a alien colony there,which is very unlikely,and ever if exist such colony the mission probabily not detect the colony ) it’s not a good place for FOCAL mission look for life…

    Perhaps it is too young for intelligent life, but not necessarily too young to have some kind of lifeforms, provided a planet exists. The Epsilon Eridani system does somewhat resemble our own: the main gas giant has a long-period orbit outside an asteroid belt (probably the orbit is nearly circular, based on stability requirements for the asteroid belt in question) and there is evidence for smaller gas giants in the outer system. Furthermore it is a system that radial velocity techniques for planet-hunting are of limited use due to activity on the star, so we need other ways to find out what’s there.

    It could be argued that Alpha Centauri is not a good place to go hunting for lifeforms either: the circumstellar discs would have been truncated roughly at the snowline, which suggests that any planets that formed there will be much, much drier than the terrestrial planets in our system. (Delivery of water from any circumbinary disc at velocities slow enough that water is accreted would have been difficult as well.) I suspect any planets orbiting Alpha Centauri A or B are going to be barren desert worlds.

  • daniel January 12, 2010, 17:16

    andy said:

    “It could be argued that Alpha Centauri is not a good place to go hunting for lifeforms either: the circumstellar discs would have been truncated roughly at the snowline, which suggests that any planets that formed there will be much, much drier than the terrestrial planets in our system. (Delivery of water from any circumbinary disc at velocities slow enough that water is accreted would have been difficult as well.) I suspect any planets orbiting Alpha Centauri A or B are going to be barren desert worlds.”

    maybe is true,but i hope there is not…

    Epsilon Eridani if there any terrestrial planet with live there,probabily still undectable, probabily there is a lot impact of asteroid and comets in the terrestrial planet,on this system

    and Alpha Centauri system if there any chance of earth-like planet with life there,it’s a old planet ~6.5 billion years it’s more easy to detect life in Alpha Centauri planet

    But anyway i think that they will launch first TPF,Darwin,NWO or any similar mission that can study many more planetary system

    then after that, they launch FOCAL for deep study in one of this planets, one with life or a least best chance of life

  • Administrator January 13, 2010, 10:56

    In response to Eniac’s question above:

    If, as Dr. Maccone has said and as I believe, any FOCAL mission must have a final close solar flyby, the ecliptic should not have much impact at all on the feasibility of a trajectory. The second to last flyby would be of a gas giant, resulting in a dive towards the sun that could be easily directed, by very small perturbations before the gas giant encounter, above or below the ecliptic. The result would be that the ecliptic would play a very minor role in the choice of trajectories. Where is this reasoning wrong?

    Dr. Maccone has now answered:

    THE REASONING IS CORRECT!
    Jupiter may be the BEST last flyby AS IT WAS FOR THE ESA MISSION ULYSSES.
    Please see the ESA web site:
    http://helio.estec.esa.nl/ulysses/mission_background.html
    Incidentally, the References there include many papers by the German ESA
    scientist, Peter Wentzel. I know Peter and had dinner with him and his wife
    once near ESTEC. This brings to my mind a new idea: for the FOCAL mission
    analysis prior to exiting the solar system, it would be advisable to consult
    with him about the possible Jupiter flyby “Ulysses-style” – to avoid the
    problems of a too close Sun flyby. Although I mentioned this possibility
    already during my November 25 lecture at the SETI Institute, I should
    probably contact Peter again about this important matter, and have him as a
    member of the FOCAL Team of the TZF…

    Thanks for making me think about this matter, and best regards to All.

  • Eniac January 13, 2010, 13:30

    Ulysses is a great example of a trajectory where flyby frees us from the tyranny of the ecliptic. The Voyagers are another.

    A final Jupiter flyby is good for Ulysses, but not for FOCAL. I think that given the unique mission trajectory required (radially outwards from the sun), a close flyby of the sun is unavoidable. There will be a direct trade-off between exposure to solar radiation and fuel required to straighten the hyperbolic trajectory into a radial one. To get into a sundiving trajectory in the first place, you need to sling around another object, any of the gas giants, that is. To get maximum benefit of the Oberth effect and reduce exposure to solar radiation, it is probably beneficial to do this as far out as possible, to make the solar flyby as fast as possible.

    So, I suppose we would first spend a few years going out to Uranus or Neptune, engines blazing, then swing around towards the sun, fly and hopefully not fry at great speed around the sun and then, engines still blazing, leave towards interstellar space, reaching final velocity long after leaving any planets way behind.

    The ecliptic could be useful, though, if we do a “gentle” flyby on the way out to help straighten the hyperbolic into a radial trajectory without expending fuel. I am not sure how much this would save, but it definitely would restrict targeting to just a handful of spots on the ecliptic, wherever the planets happen to be at the time. Given a total delta-v budget of 500-1000 km/s, just so we can get there in reasonable time, a few km/s gained from such a maneuver would only be worth it if we really don’t care where we are going, as perhaps in a CMB mission.