by Paul Gilster | Jun 20, 2005 | Sail Concepts
We’re a little over a day from the Cosmos 1 solar sail launch, testing the technologies that may one day make travel within the inner Solar System faster and far more efficient. Centauri Dreams has discussed the involvement of Ann Druyan’s Cosmos Studios; the documentary film and entertainment company put $4 million into the project, which is led by The Planetary Society. But it’s also important to acknowledge the major Russian contribution, and not just in the Volna rocket that will launch the satellite, or the Russian submarine from which it will be fired.
No, the Russian involvement is deeper still: the space firm NPO Lavochkin is behind much of the design of Cosmos 1, and the Russian Academy of Science’s Space Research Institute is a major player. All told, Cosmos 1 is a case of trans-national collaboration, a fact emphasized by the scattering of team members around the globe as the launch approaches. The Planetary Society’s Viktor Kerzhanovich is now in the Marshall Islands, setting up a temporary ground station; another ground station is in Petropavlovsk, on the Kamchatka peninsula. Both are needed because in its early orbits, the sail will not pass over the permanent ground stations set up around the globe, from Berkeley to the Czech Republic.
Emily Lakdawalla’s weblog continues to follow all this, and so, of course, does the press, with stories all over the Sunday papers, such as this one from The Washington Post or this feature in the Christian Science Monitor. Some stories focused on future uses of the sail, including the possibility of interstellar travel through beamed laser propulsion, while others stayed closer to home, noting the sail’s utility in keeping satellites in orbits that would otherwise be unstable, such as ‘polesitter’ orbits for communications, or early warning solar flare missions on satellites operating closer to the Sun than would otherwise be possible.
Image: Engineers watch a zero-gravity simulation of the sail deployment and test its mechanical configuration. This photo was taken in January 2001 at NPO Lavochkin, the world’s largest manufacturer of robotic spacecraft. Credit: Louis Friedman, The Planetary Society (c).
The approaching launch triggers the memory of that May 1951 issue of Astounding Science Fiction in which engineer Carl Wiley wrote a non-fiction article called “Clipper Ships of Space.” The idea of photon propulsion goes back as far as Kepler and traces out a distinguished history down through James Clerk Maxwell, who predicted the pressure exerted by light in 1864, and the Russian Peter Lebedev, who was the first to demonstrate that pressure in a laboratory. Wiley’s article was the first detailed account of using sails for space travel, and he evidently felt insecure enough about both idea and venue that he wrote under the pseudonym ‘Russell Saunders.’
One can imagine what Wiley would have thought about Cosmos 1, but the idea of solar sailing has had fifty years since his day to be refined through countless studies in the professional journals of astronautics. Now we find out whether all the advance work pays off. Cosmos 1, according to this Planetary Society backgrounder, will deploy its sails several days into the mission, at a time that it is within range of the two Moscow-area tracking stations. Deployment is tricky and represents one of the major challenges of solar sail work, but if this process succeeds, the ground team will then begin shifting the blades’ angles toward the Sun in an attempt to gain orbital energy.
Speed is essential, because the mylar sails will degrade within a month’s time. But assuming all goes well, a milestone in solar sail development will have occurred — a free-flying solar sail will be operational. Yes, we’ve measured photon pressure before on missions as far back as Mariner 10, and the orbits of communications satellites have to take the pressure of photons into account. But we’ve never before had a spacecraft designed from scratch around these principles.
Perhaps just as remarkable is the private nature of the mission, surely a harbinger of things to come from non-governmental sources in what seems to be the early stages of a commercial space boom.
by Paul Gilster | Jun 18, 2005 | Sail Concepts
As we near launch, let’s run through the Cosmos 1 sail mission again. The vehicle is privately funded (by Ann Druyan’s Cosmos Studios and The Planetary Society), and will be launched aboard a converted Russian ICBM. Once in orbit, the spacecraft will deploy eight mylar sails. The principle is straightforward: Photons have no mass but they do carry momentum. As solar photons strike the sail blades, Cosmos 1’s orbit should change, providing a test of solar sailing that can be measured from the ground. A later microwave beaming experiment may be able to measure the effect beamed propulsion has on the spacecraft, though the primary mission goal remains to test the principles of solar sailing by photons alone.
Launch is now scheduled for June 21 from a submerged Russian submarine in the Barents Sea. The mission will be controlled from the Lavochkin Association in Moscow and assisted by a project operations center at The Planetary Society’s headquarters in Pasadena. Everyone will be keeping a watchful eye on the Volna rocket — four years ago, a suborbital test flight meant to deploy two solar sail blades failed when the spacecraft was unable to separate from the booster.
Meanwhile, launch rehearsals have been in full gear, as reported by The Planetary Society’s Emily Lakdawalla on a mission weblog. You may remember Lakdawalla’s reporting from Darmstadt during the Huygens descent and landing. She should be equally readable here, well connected to the mission and with a fine ability to talk straight about technical subjects. Here she’s describing the mission sequence; she’s just been asked how long it will be before solar sailing is truly demonstrated:
When will you know if you have demonstrated the principle of solar sailing? I had to put the phone down and do some math on that one. If everything goes well with the commissioning of the spacecraft and the deployment of the blades on the 26th, they are going to start to use the sails to control the flight of the spacecraft on the 105th orbit, which happens on the 28th of June. By looking at data from the spacecraft’s accelerometer, Global Positioning System instrument, and from Doppler tracking of the spacecraft by Strategic Command, we hope to see the sailing effect within 1 to 10 days later. Sorry I can’t be more specific. Look at it this way: if we knew exactly how this mission was going to work, it wouldn’t be worth doing.
Which is how science is supposed to work. Name a mission in the last few years that hasn’t produced a surprise! Information on observing Cosmos 1 from the ground, assuming all goes well, is available here.
by Paul Gilster | Jun 17, 2005 | Antimatter
Two studies stand out in the list of Phase 1 awards recently announced by NASA’s Institute for Advanced Concepts (NIAC). Gerald Jackson of Hbar Technologies (Chicago) will work on “Antimatter Harvesting in Space,” while James Bickford of Draper Laboratory (Cambridge, MA) will study “Extraction of Antiparticles Concentrated in Planetary Magnetic Fields.” Both offer solutions to the huge antimatter production problem that currently has us extracting tiny amounts at fantastic price from particle accelerators here on Earth.
Jackson’s is a familiar name. He and Steve Howe at Hbar are well known in the antimatter community as proponents of a fascinating and evidently feasible antimatter sail concept that would be energized by minute amounts of antihydrogen (see this earlier Centauri Dreams story). Jackson’s new work on antimatter harvesting suggests taking antimatter collection into space, snaring antiprotons produced by the collision of cosmic rays with dust and solar wind protons.
“Just as in certain mathematical problems wherein the product of two variables respectively approaching infinity and zero can yield a finite number, the harvesting of antimatter in our solar system can produce finite and significant quantities given a big enough net,” writes Jackson in a precis of the study now available at the NIAC site (PDF warning). “The challenge is to envision a revolutionary capture and delivery architecture that generates a sufficient return on investment.”
Both Jackson and Bickford take a shot at this; Jackson’s would use concentric wire spheres as an electromagnetic trap, with the outermost sphere positively charged to repel protons from the solar wind while attracting anti-protons, which bear a negative charge. The particles would then be collected in the innermost sphere.
Bickford’s idea is to use a magnetic scoop to extract antiprotons trapped within planetary magnetic fields. He estimates that 10 micrograms of antiprotons and 10 milligrams of positrons are contained within the Earth’s magnetosphere at any given time. Significantly larger quantities should be found in the radiation belts of the Jovian planets. The collector involved is an adaptation of an idea first proposed by Robert W. Bussard for interstellar propulsion, in this case an electromagnetic scoop attached to a satellite in planetary orbit.
Image: An electromagnetic scoop first appears in interstellar studies as a Bussard ‘ramjet,’ capable of fantastic speeds, but now thought unfeasible because of drag constraints. New proposals, however, use magnetic scoop technology to mine space-borne antimatter. Credit: ESA/ITSF; Manchu.
Each Phase 1 NIAC study receives $75,000 for a six month period in which to prove the viability of the concept and identify the obstacles that must be overcome to make the proposal a reality. A limited number of NIAC studies then receive Phase II funding. The complete list of the current Phase 1 proposals is available here. And in case you missed it, here is a good Washington Post story by Joel Achenbach from May 15 that covers commercial activity in space, with a sidebar on NIAC.
by Paul Gilster | Jun 16, 2005 | Exoplanetary Science |
With exquisite timing, the SETI Institute has announced the first of a series of workshops to study the habitability of planets around M-class red dwarfs. The issue became highly visible recently with the announcement of the rocky planet discovered around the red dwarf Gliese 876, some 15 light years from Earth. Although thought to be too hot for life as we know it, the new planet is a solid world orbiting a main sequence star, raising the question of genuinely terrestrial worlds around such stars.
‘Main sequence’ refers to stars that burn hydrogen in their cores, those that show up in a well-defined band on the famous Hertzsprung-Russell (HR) diagram, which plots the intrinsic brightness of stars against their surface temperatures (intrinsic brightness is the observed brightness of the star corrected for distance). Moving off the main sequence takes you into the domain of red giants, red and yellow supergiants, and white dwarfs. But way down on the lower right of the HR diagram, and still on the main sequence, are low mass red dwarfs like Gliese 876.
And there are plenty of such stars. According to Jill Tarter, the Director of the Center for SETI Research at the SETI Institute, “Most stars in our galactic neighborhood are M stars; historically we’ve excluded them because planets within their classically defined ‘habitable zone’ would be tidally locked to the star and have to endure periodic flares of hard radiation. This historical wisdom may require revision in light of newer atmospheric models and a new appreciation of extremophiles on Earth. Our list of target stars for SETI may be about to get a lot bigger.”
Image: Here’s another star from the Gliese catalog (not the one around which the new planet was found). Gliese 623b is one of the least massive main sequence stars ever found, some 60,000 times fainter than the Sun. This double star system is 25 light years from Earth in the constellation Hercules. Can tiny red dwarfs like this produce conditions suitable for life? Credit: Cesare Barbieri, University of Padua, and NASA/ESA.
The Tarter quote comes from a news release from the SETI Institute, which will host the workshop from July 18 to 20 at the Institute’s headquarters in Mountain View, CA some 40 miles south of San Francisco and 10 miles north of San Jose (this is virtually next door to NASA’s Ames Research Center). Full information including directions to the conference site can be found here. A second workshop is planned in another 12 to 18 months to examine preliminary work initiated by the first conference.
With 70 percent of all stars in the Milky Way now thought to be red dwarfs, and with the target selections for Terrestrial Planet Finder an obvious priority, this conference could not be more timely. “It may well be that there are far more habitable planets orbiting M dwarfs than orbiting all other types of stars combined,” said Frank Drake, the Director of the SETI Institute’s Center for the Study of Life in the Universe. The Institute will use the results of its workshops to plan future observations using the Allen Telescope Array (ATA), and the work should feed into future studies with SonATA, a system now being designed to examine one million stars for extraterrestrial signals.
Be aware of Heath, M.J., Doyle, L.R., Joshi, M.M. et al., “Habitability of planets around red dwarf stars,” Origins of Life 29, 405-424 (1999). Also note Jill Tarter’s paper with Margaret C. Turnbull, “Target Selection for SETI. I. A Catalog of Nearby Habitable Stellar Systems,” Astrophysical Journal Supplement Series 145, 181-198 (March, 2003), available on the SETI Institute site (PDF warning).
by Paul Gilster | Jun 15, 2005 | Exoplanetary Science
Yesterday’s post “On Red Dwarf Stars and the Hunt for Life” incorrectly stated the lifespan of an M-class red dwarf star as 100 times that of the Sun. The correct figure is ten times as long, making an age limit of perhaps 100 billion years for the average red dwarf. G-class stars like the Sun are expected to live about ten billion years. The red dwarf Gliese 876 is about 11 billion years old, more than twice the age of the Sun.
