by Paul Gilster | Oct 26, 2004 | Antimatter
Antihydrogen, now produced for the first time in Switzerland at the CERN facility, may be the ultimate fuel, producing a thousand times more energy than fission or fusion methods. But what will it take to produce enough antihydrogen for practical use? After all, we now produce antimatter in the amount of mere nanograms per year.
And ponder this: CERN estimates that, to create a kilogram of antimatter with present methods would take all the energy produced on the Earth for ten million years. Considered in more everyday terms, the amount of antimatter produced each year in an accelerator laboratory like CERN or Fermilab is about enough to make a 100-watt bulb shine for fifteen minutes.
What we need is a dedicated antiproton source, an idea often discussed by interstellar guru Robert Forward, and now advanced in a new paper to be published in the Prceedings of the 2004 NASA/JPL Workshop on Physics for Planetary Exploration. First noted in SpaceRef, the title is “Controlled Antihydrogen Propulsion for NASA’s Future in Very Deep Space.” The authors are Michael Martin Nieto, Michael H. Holzscheiter and Slava G. Turyshev. Among their conclusions:
It would take about 5 years and ~ 0.5 B$ to build a source.
It would take about the same time and money more to develop antihydrogen handling technologies.
During all this time effort would be given to developing the new antiproton production technology that is needed. Current antiproton production rates are low. While clever techniques can enhance these rates by several order of magnitude and quantities sufficient for advanced concepts can be produced given enough economic and political pressure onto the few available sources, a real breakthrough can only come through continued interest and research in this area. A good analogy is the comparison between a light bulb and a laser. In both cases light is produced, but in one system through thermal heating of a material and in the other through coherent processes. Antiprotons are currently produced by heating a metal target with a primary proton beam. This is a direct analogy to the light bulb — we are still awaiting the invention of a ‘laser-equivalent’ for the production of particles of antimatter.
A GUESS is that 10-20 years more would be needed for this.
The article on the ArXiv server is available in PDF form here.
by Paul Gilster | Oct 25, 2004 | Autonomy and Robotics
Apropos of the Cassini material below, IEEE Spectrum Online is running a remarkable story telling how a Swedish engineer discovered a potentially fatal flaw in the communications procedures between Cassini and the Huygens probe that will land on Titan. Corrections to Cassini’s trajectory may have saved the mission. Must reading on the subject of spacecraft autonomy and repair.
by Paul Gilster | Oct 25, 2004 | Outer Solar System
The Cassini Saturn orbiter will make its closest approach yet to Titan tomorrow, traveling 1200 kilometers (745 miles) above the surface at a speed of 6.1 kilometers per second. This will be the first time Cassini has used its radar instruments to image the moon. Confirmation that data from the flyby were successfully received won’t come in until evening (6:30 PM PDT) on the 26th.
A close look at the imaging and radar data will be fascinating in itself, but this flyby is also a crucial part of the attempt to land the Huygens probe on Titan, an event now scheduled for January 14, 2005 (with separation of the lander from Cassini on Christmas day). A prime objective is to determine whether the landing area for the probe is solid or liquid in nature.
Image: Encircled in purple stratospheric haze, Titan appears as a softly glowing sphere in this colorized image taken one day after Cassini’s first flyby of that moon. Credit: NASA/JPL/Space Science Institute.
Says professor Michele Dougherty of Imperial College, lead scientist for the magnetometer instrument on Cassini, “Titan’s atmosphere is similar to the very early atmosphere of the Earth and by studying its properties we can start to unravel some of the mysteries of the planet. The Cassini Magnetometer experiment will investigate Titan’s interior and variations in the magnetic field measurements could indicate the presence of an ocean contaminated by salty materials like in the Earth’s oceans and in the hypothesised oceans of Callisto and Europa in the Jovian System.”
The Huygens lander — and Cassini itself — are vivid reminders of the importance of autonomous systems. Consider the flight software Huygens will use to deploy its parachutes for the descent to Titan’s surface next January. Produced by a British company called LogicaCMG, the software will need to deploy Huygens’ chutes, separate the front and back shields precisely on time, maintain a pre-determined descent profile that will reduce Huygens’ velocity before beginning its scientific experiments, and manage spacecraft-to-spacecraft communications with Cassini. All this with round-trip radio communications delays that preclude any help whatsoever from controllers on Earth.
And Titan is positively next door compared to an interstellar destination. Robotic systems that can maintain a space vehicle and conduct science for decades at a time will be needed before we ever consider launching a probe to the nearest star, which is one reason why artificial intelligence and autonomy loom large in the thinking of deep space theorists. Huygens is a fascinating and necessary early step in that direction.
Cassini’s closest approach to Titan is at 9.44 am PDT. The first downlink occurs at approximately 6.30 pm PDT; NASA TV coverage will run from 6.30 pm to midnight PDT. Check here for updates to NASA TV scheduling. And here is the primary Cassini-Huygens mission page. Sources: press release from the Particle Physics and Astronomy Research Council (UK); various NASA Web pages.
by Paul Gilster | Oct 23, 2004 | Breakthrough Propulsion
Why keep a close eye on nanotechnology? The Foresight Institute’s Conference on Advanced Nanotechnology, closing tomorrow at the Crystal City Marriott in Washington DC, is loaded with reasons, but for interstellar theorists, the answer is mass. Ponder this: the Project Daedalus multi-stage starship, designed by the British Interplanetary Society and the first complete theoretical study of an interstellar probe, carried 50,000 tons of fuel to push a 500 ton payload. And Daedalus used nuclear-pulse propulsion; the fuel to payload ratio gets far worse with utterly inadequate chemical rockets.
Nanotechnology offers the bright promise of interstellar probes so small as to dwarf the imagination, with corresponding savings in propulsion systems, yet capable of assembling full-scale observation platforms at their target star. One of the major speakers at the Foresignt Institute conference is Robert Freitas, a giant in the field of nanotechnology and a senior research fellow at the Institute for Molecular Manufacturing. He is also the author of the Nanomedicine book series.
I relied heavily on Freitas’ extrapolations of tiny ‘needle’ probes in the last chapter of Centauri Dreams, a concept that has now replaced in his thinking his older REPRO probe, which was a kind of super-Daedalus with the ability to reproduce itself at each target star system and thus continue the human wave of exploration ever outward. Chances are we’ll never see probes the size of REPRO, but take a look at Freitas’ A Self-Reproducing Interstellar Probe for a still fascinating look at how we viewed space exploration before the nano-revolution began.
Freitas has been having a running argument with Nobel laureate Richard Smalley over how feasible molecular manufacturing actually is (or will be), but whatever his topic, his work is worth studying. Be aware that both Adam Keiper (editor of The New Atlantis ) and Howard Lovy at Nanobot are reporting on this meeting with live blog entries. Being able to participate ‘virtually’ through their work is powerfully instructive, and keeps those of us unable to attend abreast of the most recent developments. What an extraordinary contribution the weblog community can make in covering such events.
by Paul Gilster | Oct 22, 2004 | Sail Concepts
The Planetary Society has struck two agreements with US government agencies to track its Cosmos 1 solar sail. Although ground stations near Moscow will provide the bulk of the tracking, the National Oceanic and Atmospheric Administration (NOAA) will also monitor the mission from its National Environmental Satellite Data Information Service site in Alaska. The US Air Force, meanwhile, will provide images of the deployed sail from the Air Force Maui Optical and Supercomputing site at Haleakala, Hawaii. Other tracking will be provided by the University of California’s Berkeley Space Science Laboratory ground station and a ground station in the Czech Republic.
Funded by The Planetary Society and Cosmos Studios, the spacecraft was built in Russia by NPO Lavochkin and the Space Research Institute. Planetary Society executive director Louis Friedman has announced that all electronic systems aboard the spacecraft have been flight-qualified and the components have been shipped to the NPO Lavochkin facility for final integration into the frame of the vehicle. The completed craft may be sent to the launch preparation site near Murmansk as soon as the end of this year; it is to be launched from a Russian nuclear submarine aboard a Volna missile from the old Soviet nuclear arsenal. If successful, Cosmos 1 will become the first free-flying solar sail.
Centauri Dreams‘ take: Cosmos 1 is an educational event, meant as an outreach to the public on behalf of the concept of solar sailing. If successful, it will raise awareness of the technology and perhaps spark further commercial work. It is not an attempt to develop solar sails to the point where serious science missions can be flown, although some science (such as James Benford’s microwave experiment, which will use the Goldstone dish to attempt to demonstrate beamed propulsion) will take place on the mission.
But when I talked to NASA solar sail expert Sandy Montgomery at Marshall Space Flight Center last year about what comes next, he pointed to the hard engineering work to follow. “I appreciate what [the Cosmos 1 team] is doing and am looking forward to it with great interest. But we need to continue with a solid NASA engineering approach to answer the questions for materials that will survive for long periods in space, using mechanisms that are well understood. Ultimately,” Montgomery added, “we need to retire a lot of the risk so that a scientist who has to choose between a known chemical mission of a short duration and a sail mission of a longer duration won’t find any great amount of risk in that sail and therefore choose not to use it.”
