By Larry Klaes
Tau Zero journalist Larry Klaes takes a look at Mason Peck’s work with reconfigurable space structures. Anyone who ponders the future of large structures in the Solar System — and this might include space-based telescopes, O’Neill habitats or perhaps one day enormous lenses of the sort Robert Forward envisioned — will wonder how such creations can be assembled. Potential solutions may one day grow out of Peck’s work, until recently funded by NIAC. Centauri Dreams also wonders how such theories will be supplemented by nanotechnological techniques that may one day return us to the era of thinking big in environments far from home.
Space is a promising but often difficult environment to work in. A typical spacecraft has to deal with a near vacuum, extreme temperatures, radiation fields, and micrometeoroids. With space ‘starting’ at one hundred miles above Earth’s surface, a region attainable at present only with expensive rockets, sending up numerous vehicles that have to work autonomously many times over while carrying their own resources merely adds to the daunting task of utilizing the Final Frontier.
One potential solution to some of these issues is being explored by Dr. Mason Peck, an assistant professor of mechanical and aerospace engineering at Cornell and director of the Space Systems Design Studio. Peck and his university team have been experimenting with the amazing properties of superconductivity, which involves the ability of an object to conduct electricity indefinitely with no resistance under certain conditions.
Peck is investigating an unusual property of type II superconductors called magnetic flux pinning, which may provide an ideal technology for in-orbit self-assembly of modular spacecraft and satellite formations. He calls these ‘non-contacting modular reconfigurable spacecraft.’
“A magnet on one spacecraft module interacts with a superconductor on another module. One becomes pinned to the other, but across some distance of empty space,” explains Peck. “At the moment that distance is on the order of centimeters. We would like to extend it by a factor of 10 or 100. We have some ideas about how to do that [in ways] more interesting than simply using bigger magnets and bigger superconductors.”
As for transferring data and power from one spacecraft module to another in space, Peck envisions infrared lasers being the key to making this process a reality. He and his team were able to demonstrate this principle in the laboratory in 2005 with infrared LEDs and specially designed photovoltaic cells.
Image: A composite of various lab demonstrations, computer models, and artwork related to modular spacecraft and the methods used in creating them. Credit: Mason Peck.
Among the applications Peck sees for this technology are spacecraft docking, sparse-aperture telescopes with individual mirror segments flux-pinned together, and the assembly or reconfiguration of space structures without mechanical hardware.
“In this project we are investigating spacecraft modules that would be constructed with interfaces consisting of combinations of magnets and superconductors, establishing a non-contacting interaction between the modules,” says Peck. “This action-at-a-distance interaction overcomes the limitations of other spacecraft-positioning strategies that involve electromagnetic fields. It allows fractionated or modular spacecraft to fix their relative positions and orientations without any mechanical connection, active control, or power expenditure. Power is in short supply in space, and robustness to power failures is an important objective of any spacecraft; so this technique is perfect for space applications.”
Last summer Peck and his team completed two experiments investigating their concept of operating multiple craft together in space.
“Our results indicate that flux pinning is promising for modular spacecraft assembly and station-keeping applications, providing mechanical stiffnesses over 200 Newtons per meter (N/m) at small (5 millimeter) magnet-superconductor separations and potentially useful non-zero stiffnesses at larger (over 3 centimeter) separations, with significant damping,” Peck adds. “We find that increasing the magnetic flux density at the superconductor surface strengthens the flux pinning forces, suggesting the possibility that higher stiffness can be obtained over larger distances by increasing or focusing the magnetostatic field.”
The basic idea of modularizing spacecraft is not new, going back to the first decades of the Space Age with the Apollo Command/Service Module docking with the Lunar Module. Later years would see manned craft from both the United States and Soviet Union docking with the first space stations in Earth orbit. Certain collections of space satellites have been conducting formation flights since the 1980s.
Peck’s project was funded by NASA’s Institute for Advanced Concepts (NIAC) until last year, when the space agency shut down the institution. Since then Northrop Grumman Space Technologies (NGST) has sponsored some of the work in the form of a gift to Cornell University. Peck also hopes to receive funding from DARPA, the Defense Advanced Research Projects Agency, in the near future.
“We anticipate that this technology will be very relevant to DARPA’s System F6 program, also known as the ‘Future Fast, Flexible, Fractionated, Free-Flying Spacecraft united by Information exchange.'” The primary goal of the System F6 program is to replace a more traditional ‘monolithic’ satellite with a cluster of modular satellites that can act as well as, if not better, than a single vehicle.
Cornell graduate student Joe Shoer hopes to launch a CubeSat demonstration of Peck’s non-contacting modular reconfigurable spacecraft design in a few years.
“CubeSat launches are relatively inexpensive: $50,000 to launch, probably $15,000 for the hardware we have in mind. So, we don’t need much,” says Peck. “We had also hoped to try a demo on NASA’s zero-gravity aircraft, but some other projects have taken more time and we find ourselves without enough resources (people and funds) at the moment. There is some possibility that DARPA’s F6 flight demo will include something along these lines.”
Among the innovative ideas Peck hopes become reality one day are space telescopes comprised of many discrete mirrors large enough to resolve planets circling distant stars. The Cornell professor also sees such modules as safe places for astronauts to store their equipment when working outside their vessels in the space environment.
“No longer are we required to distinguish among spacecraft subsystems, individual spacecraft, and constellations of spacecraft. Instead, the proposed concept blurs the distinction between modular spacecraft and formation flying, between spacecraft bus and payload, and to some extent between empty space and solid matter. Articulated payloads, reconfigurable space stations, and adaptable satellite architectures are possible without the mass and power typically associated with maintaining relative position and mechanically rebuilding structures.”
More information on non-contacting modular reconfigurable spacecraft is available here.
Question, do only certain materials become superconducting when super-cold, or can any material gain these properties?
I watched a Science Channel show recently where a plastic puck became magnetic when super-cold and levitated above a track is why I’m asking.
dad2059, superconductivity (no electrical resistance whatsoever) seems to depend on the material. It doesn’t happen with gold and silver, for example, but does show up in aluminum and metallic alloys, among other materials. Here’s a snip from the Wikipedia that’s useful: “…in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit. Even near absolute zero a real sample of copper shows a non-zero resistance. The resistance of a superconductor, on the other hand, drops abruptly to zero when the material is cooled below its ‘critical temperature.'”
It sounds like what’s being talked about here is something surprisingly similar to the old SF idea of building with forcefields. Do I understand this right? Are we talking about creating clusters of unconnected components that are held rigidly in place by magnetic fields even without touching each other? I don’t quite see how that works — I can get a field causing a continuous pull or push, but I don’t get how that pull suddenly stops pulling and holds an object at a fixed distance.
And how rigid a connection are we talking about? If one component of, say, a multi-piece spaceship were under thrust, would the other components travel with it and stay in the same orientation? Could astronauts push off from one module to the next and have them stay in place? Could you have something like, say, the starship Enterprise without the connecting pylons?
And is this something that would require power to maintain, like a fictional forcefield, or would it be intrinsic to the materials?
Christopher, let me see if I can get a comment on these questions from Mason Peck himself. I’d take a crack at them but I don’t want to misrepresent anything Peck is saying. I’ll hope to have more on this later today, or Larry may want to weigh in with some thoughts of his own.
Hi dad2059, Christopher, and Paul;
A really cool spin on modular space craft would be that involving modular inflatable structures such as those made of thick fabrics comprised of graphite aramid materials such as carbon fiber and Kevlar or perhaps carbon fiber and the new material Zylon which has a tensile strength of about 800,000 PSI which is I believe about 2 1/2 times greater than that for Kevlar which is about 5 times as strong as construction grade mild steel. I could see a whole host of structures resulting from inflatable space based modules such as inflatable sails for reflecting concentrated beamed electromagnetic energy, parabolic dish type inflatable reflectors for concentrating sunlight onto photovoltaic cells, thermoelectric cells, or turboelectiric machinery to power electron, ior on rockets. For further mass specific power capture for final end electromagnetic energy concentrating apparatus, the impinging energy could originate from a artificial laser or maser like beam wherein the beam’s energy flux density at the location of the reflector is several times that of the ambient sunlight.
Whatever the purpose of the inflatable space structures, they could be optionally seperately launched and joined together by pressure seals perhaps with Velcro like reinforcement of tongue and groove or zip-lock type sealing mechanisms. Magnets could also be utilized whether or not the magnets are permanent magnets or Solar PV powered electromagnetics etc..
In short, I think modular space craft of any types is a cool idea and should prove useful.
Thanks;
Your Friend Jim
Hi James
That idea plays perfectly into Bigelow Aerospace’s inflatable habitat scheme.
Lower launch weights means cheaper launch costs. As the technology improves, the price should drop further.
Pentagon awards contract for ‘fractionated’ satellites
Washington (AFP) March 5, 2008 – Lockheed Martin has
been awarded a 5.7 million dollar Pentagon contract to
design clusters of small, individually launched satellites
that can operate as a network in space, the company
said Wednesday.
The contract awarded by the Defense Advanced Research
Agency (DARPA) was for the first phase of a program
dubbed “F6,” which stands for “Future, Fast, Flexible,
Fractionated, Free-Flying Space … more
http://www.spacedaily.com/reports/Pentagon_awards_contract_for_fractionated_satellites_999.html
Magnets help spacecraft fly in formation
19:46 06 May 2008
NewScientist.com news service
David Shiga
Superconducting magnets could help a fleet of spacecraft fly in precise formation without using up limited fuel reserves, two groups of researchers say. But others foresee problems with the technology.
Many proposals for groundbreaking space missions require multiple spacecraft to fly in formation, including NASA’s Terrestrial Planet Finder, which would hunt for Earth-like planets around other stars, and the Laser Interferometer Space Antenna (LISA), which would search for ripples in the fabric of space called gravitational waves.
One way to keep spacecraft in the right arrangement is to use thrusters, which fire jets of gas to push a craft in the opposite direction. Unfortunately, thrusters can limit the lifetime of a mission because they rely on limited supplies of fuel.
But two groups of researchers are developing a technology that replaces thrusters with electromagnets.
Full article plus video and images here:
http://space.newscientist.com/article/dn13846?DCMP=NLC-nletter&nsref=dn13846
Superconductors get a boost from pressure
PhysOrg.com May 19, 2008
Scientists have found that the
superconducting state in so-called
“high temperature” superconductors
can be induced by high pressure as
well as low temperature.
Superconductors can carry over 150
times more electricity than copper
wires because they don’t restrict
electron movement. But currently,
materials have to be cooled below
around minus…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8716&m=25748
Concept space station designed for long term space habitation
Naveen | Feb 24 2009
Let’s take a break from the mundane design concepts and do some space exploration. Well, I am talking about the concept space station designed by André Dettler. This concept was a submission for the “Design the Future” contest, which was presented by Solidworks and NASA.
The Gallagher Space Center has been conceptualized with an intention for long term space habitation for workers. The spherical design of the space station is composed of different modules and the outer perimeter blocks harmful radiation from the sun while constantly converting solar energy.
The modules can be rearranged for specific purposes such as research work and personal care. Moreover, the spherical shape allows the inhabitants to look out of the windows and clearly observe the surroundings. This visual communication benefits people psychologically for long term habitation, which is the prime focus of this project.
http://www.thedesignblog.org/entry/concept-space-station-designed-for-long-term-space-habitation/
Determination of Spacecraft Attitude and Source Position Using Non-aligned Detectors in Spin-stabilized Satellites
Authors: Srikanta Sinha
(Submitted on 2 Sep 2009)
Abstract: The modulation of high-energy transients’ (or steadily emitting sources’) light curves due to the imperfect alignment of the detector’s view axis with the spin axis in a spin-stabilized satellite is derived. It is shown how the orientation of the detector’s view axis with respect to the satellite’s spin axis may be estimated using observed light curves. The effects of statistical fluctuations are considered.
Conversely, it is shown how the attitude of a spin-axis stabilized satellite as well as the unknown position of a celestial source of high-energy photons may be determined using a detector whose view-axis is intentionally kept inclined and is known accurately beforehand. The case of three-axes stabilized satellites is also discussed.
Comments: 8 pages, 3 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:0909.0484v1 [astro-ph.IM]
Submission history
From: Srikanta Sinha [view email]
[v1] Wed, 2 Sep 2009 18:03:06 GMT (46kb)
http://arxiv.org/abs/0909.0484