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.
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.
I think if one were to do a focal mission to study exoplanets, one should choose a set of candidate stars that are positioned such that the probe could follow some nice trajectory to study all of them in one mission.
It’s a nice idea, but I’m afraid that such a trajectory isn’t practical. What we’d need to do instead is assign a different probe to each target, because with near-term technologies, we won’t be able to move the probe into the much different trajectories required to study, say, a series of nearby stars. Once the FOCAL concept is demonstrated on a single target, we can hope that long-term costs decline to the point where we can create additional FOCAL missions for other interesting targets. But for any single mission, the positioning tolerances are very tight.
Hi Paul;
I like the idea of nuclear electrical propulsion using some sort of improved and modified version the the former USSR TOPAZ space based nuclear reactors. The practice that we get doing a FOCAL mission can be applied to doing nuclear fission powered generation star ships.
The fuel carried aboard such star ships might exist in the form of Thorium isotopes and the like where reactor fuel is bread in route in breeder reactors so as to avoid the dangers of concentrated fissile materials such as U-235 and the like.
All,
VASMIR using a nuclear fission reactor as its power source could get the FOCAL Probe to the required location (~550 Au’s out) in ~3 years years to study the Alpha Centauri System in detail, provided of course that previous surveys detect something there of interest to study. The added benefit of using VASMIR if we did this right would be to fully prove out VASMIR propulsion for human crewed Interplanetary travel within our Solar System. The other option might be to build a hybrid that would include either Solar Sail technology or Ion propulsion combined with VASMIR/nuclear reactor to prove out at least two new types of propulsion technology as part of the FOCAL mission,
The FOCAL mission would be expensive, but if done right it could serve multiple purposes which might make it much more cost-effective. There is no reason why a FOCAL+VASMIR could not be developed and launched by the early 2020’s with the first data returns coming into Earth by 2025. This is the timeline that the FOCAL mission should shoot for to keep people interested. It would also help if it could be designed to do as much of a near Sol/Terra Survey as possible especially in conjunction with other survey probes such as TPF and Webster Cash’s New Worlds Imager combined with JWST and Ground Based Telescopes
The real question is where might FOCAL fit as part of a 15 year plan and integrated Architecture for surveying within a 60 Light Year radius of Sol/Terra so we begin to understand what our immediate neighborhood looks like.
Ken
The beryllium balloon solar-sail can reach 400 km/s with a solar fry-by – just nine years to the 763 AU range for optical gravity-lensing.
Adam: What is the technological readiness of the Beryllium solar sail at 400 km/s? From what I have seen, you should at least have said “could” instead of “can”, as I understand that readiness consists of one entirely theoretical publication. At least VASIMR has hardware, and other, more conservative electric thrusters could also be used, with reactors based on decades old and tested designs.
I have the feeling that solar sails, for this mission, are considered mostly out of a “fear of fear”, in which people who themselves have no problem with the thing itself still dread the “N-word”. I do not think that is useful or appropriate for this mission.
Eniac, I’m the last person to discount the idea of nuclear power for a space-probe but achieving a final velocity of 400 km/s with VASIMR is not a near term prospect. Just how long would a probe take using a VASIMR to hit that speed and for what power requirement? Take the Mars Mission design with a 20 ton payload and a 12 MW reactor power-source – which doesn’t yet exist for space applications mind you – and masses ~120 tons. At peak exhaust velocity it gets ~56 newtons thrust, with an impressive 70% efficiency in power conversion. What acceleration is that? Just ~1/20,000th of a gee and it would need ~28 years to get to 400 km/s. Or one could accelerate all the way to 763 AU and take at least ~35 years to do it. And that’s not factoring in the burden of a mass-ratio.
Solar-sails have a zero propulsive power requirement, which is not an inconsiderable factor in their favour. And in this case they accelerate a lot quicker than any near-term nuke design, aside from nuke-pulse like “Orion” – and more than ‘Greens’ would object to that idea. Not me – I’d ground launch an ‘Orion’ for the right mission – but the world’s military would have issue with such a massive ‘cartridge’ of 1 kiloton fission bombs in orbit.
Wouldn’t such an instrument be very suitable for detecting (even direct imaging and spectroanalysis) of planets in another galaxy, foremost Andromeda?
The huge advantage of this, in comparison with an individual star within our own galaxy (such as Alph Cen), would be that there would be an enormous number of potential targets within a relatively small angle, which in turn would require the instrument to move only a very small distance in order to acquire the next target.
A relevant question here is: how wide is the field of view at such a distance, and is this field of view related to distance or not? If this is very small (narrow), a particular planet in Andromeda might stay within view too short to be of use.
Can anyone shed some light on this?
Good questions, Ronald. Let me float this issue past Claudio Maccone and get back to you.
Have to wonder whether it would be more worthwhile targeting globular clusters than an individual star system in terms of scientific return…
@andy: yes, your point about targeting globular clusters in stead of individual stars as being more effective/efficient is similar to mine about targeting galaxies like Andromeda.
However, with (old) globular clusters an issue may be low metallicity and resulting (near) absence of planets.
The folks at http://futuretimeline.net think that we’ll have interstellar travel by 2150. They also say that humanity will become a Type I civilization by 2250, a Type II civilization by 3100 and a Type III civilization by 1000000.
What do you think? Could it be plausible?
@Ronald: I’m not convinced that the situation is all doom-and-gloom in globular cluster planet prospects. There are suggestions that the planet-metallicity correlation flattens out at lower metallicites, and while hot Jupiters seem to be absent in globular clusters, planets on wider orbits may be more frequent. Bear in mind that not all stars in a globular cluster would necessarily have passed through the core yet, so such systems would not necessarily have been destroyed over the history of the cluster.
@andy: thanks, could the same be true for elliptical galaxies? I read that those are generally also low in metallicity. Is that true anyway? Recent research seems to suggest that spiral galaxies probably have a similar origin and early history as ellipticals, but the spirals have gone through several mergers with other (mainly dwarf) galaxies.
@Danny: I would say that any prediction about our human future of more than say 20 years is pure speculation.
It is easy to extrapolate lines and this is ok for short term trends and developments. But for the longer term it is totally unreliable because it does not take entirely new discoveries and developments into account.
I believe a lot will hinge on two things:
– our ability as humankind to harness abundant (really large) amounts of clean, cheap, sustainable energy, in particular solar (for low-intensity processes, maintenance of society) and nuclear (for high-intensity processes, such as space travel), ultimately nuclear fusion.
– the soci0-psychological and political willingness to be and remain outward looking, enterprising and exploratory as a civilization.
They will both be crucial, I don’t know which one the most.
Just this morning I head a headline in a major newspaper saying “Thank God, no more manned spaceflight”.
Regardless of the scientific value of manned space flight and the greater (present) cost-efficiency of unmanned space exploration, this kind of statement alarms me. Because it wasn’t about scientific value, cost-effectiveness, alternatives, etc., but just the usual clichés about ‘waste of money’, ‘better spent on other things’, blabla.
In another thread here (Toward an Interstellar Archeology, 2 febr.) we just had this coming up: an inward looking civilization might be a decadent one, on its way to decline and oblivion.
Is it possible for light from Earth to be “focaled” by another star then “focaled” again by a second star and a third and so on until the light found its way back to earth and you could look at Earth as it was say a million or 100 million years ago however long it took for the light to make the jouney if you knew where to point the telescope?
@Ronald: IIRC the giant ellipticals (such as M87) have quite respectable metallicities, though it seems it is easier to find numbers for the globular cluster population (which like many of the globulars in our galaxy are metal poor) than the galaxy itself. The metal poor narrative seems to apply mainly to the dwarf galaxies.
Ronald:
I think this is an excellent point. A nearby galaxy is quite probably the richest target you can find. However, it is not clear how many things you will find that are new, as looking at another galaxy with FOCAL probably will not show more detail than looking at our own with conventional telescopes. I highly doubt you could detect planets. Still, the different vantage point and choice of galaxy should make it well worth it.
To me, it is more interesting to look at things you couldn’t see at all, otherwise, such as stellar and exoplanetary surfaces, our galactic nucleus, or the CMB at high detail.