Missions | Centauri Dreams

ESA: Tuning Up the Darwin Mission

by Paul Gilster | Apr 13, 2007 | Exoplanetary Science, Missions | 3 Comments

What on Earth (or off it) is an Optical Delay Line (ODL)? It turns out to be, according to the European Space Agency, "...a sophisticated opto-mechanical device that can introduce well-defined variations, or delays, in the optical path of a light beam..." And it's a key player in the technique known as nulling interferometry, which ESA's Darwin mission will use to dampen the glare of distant stars while exposing the light of their planets. Darwin will be a multi-satellite mission using multiple orbiting telescopes working together to produce a much larger effective aperture than any one of them can muster. As to that ODL, the optical delay it introduces has to be able to adjust the path of a beam of light with an accuracy measured in just a few nanometers (billionths of a meter). To achieve this, the agency is testing a design using magnetic levitation to control its mirror, a contactless and frictionless method ESA likens to the touch of a feather (a video clip is available). What's...

A Note on the Enzmann Starship

by Paul Gilster | Apr 1, 2007 | Missions | 1 Comment

The always reliable Adam Crowl takes on fueling requirements for starship projects like Daedalus, with an interesting look at alternatives for mining He3. The Daedalus team, members of the British Interplanetary Society who created the first in-depth study of a starship, had hoped to tap Jupiter's atmosphere for the job, but Crowl examines Saturn, Uranus and Neptune as well, finding Saturn the best fit. Adam then tackles a fascinating article by G. Harry Stine (thereby launching me on a search for the back issue of the magazine in question, now almost irretrievably hidden in the recesses of my office). Here's how he describes it in Crowlspace: I have just received an issue of the October 1973 Analog - the one with a gorgeous Rick Sternbach cover of two Enzmann starships and the cover article by G. Harry Stine, "A Program for Star Flight". It's quite a memorable article as Stine was arguing for a star flight program to begin c.1990, and the development of a massive in-space industrial...

Rosetta’s Mars Flyby

by Paul Gilster | Feb 25, 2007 | Missions | 1 Comment

Centauri Dreams usually confines itself to the outer planets and beyond, but this photo of Mars taken by the Rosetta spacecraft's Philae lander is just too unusual to pass up. You can see one of Rosetta's solar arrays in the foreground, with the Syrtis region on the Martian surface some 1000 kilometers below. The lander is scheduled for a 2014 touchdown on comet 67P Churyumov-Gerasimenko. Numerous system checks are ahead as Rosetta prepares for a near-Earth swingby in November of this year. Image: Stunning image taken by the CIVA imaging instrument on Rosetta's Philae lander just 4 minutes before closest approach to Mars. Credit: CIVA/Philae/ESA Rosetta.

Envisioning the Interstellar Ark

by Paul Gilster | Feb 20, 2007 | Culture and Society, Missions | 20 Comments

Strange Paths offers a robust essay on the topic of interstellar arks, one that considers our future among the stars without warp drives or other breakthroughs that get us past the speed of light barrier. Star Trek and its ilk offer familiar, short-term travel analogous to our own relatively brief journeys in the Solar System. The real thing may be different: The way toward stars becomes however quite unfamiliar if we consider that such Triumph of Physics could possibly not happen, and that the famous constant of Einstein c, the speed of light (3E8 m/s), represents an horizon speed which is impossible to exceed and which is even extraordinarily difficult to approach, so that we would begin to see outer space like it is seen by astronomers: a vastness compared to which that of terrestrial oceans is nothing. The author looks at two alternatives, the first being a relativistic rocket able to take advantage of time dilation at velocities close to light speed so that the crew experiences...

New Horizons Primes for Jupiter

by Paul Gilster | Jan 19, 2007 | Missions, Outer Solar System | 5 Comments

The New Horizons mission may have one primary target, the Pluto/Charon binary at the edge of the Kuiper Belt, but the science along the way should be interesting indeed. Up next in late February is the Jupiter flyby, whose powerful gravity assist will boost New Horizons' velocity past 23 km/s and provide the needed stress tests to put onboard instrumentation through its paces and refine the methods for data collection. But there's plenty to do in Jupiter space beyond setting up for the 2015 Pluto encounter. For one thing, Jupiter's magnetosphere extends far beyond the planet itself, and New Horizons will be the first probe to move along the 'tail' of this stream of charged particles. These studies will complement the earlier magnetosphere work of Cassini and Galileo. All told, 700 observations of Jupiter and the Galilean moons are planned, with data gathering from January through June, including looks at the ring system and a close-up look at the 'Little Red Spot' the storm that's...

Fast Track to 200 AU

by Paul Gilster | Jan 10, 2007 | Interstellar Medium, Missions | 2 Comments

Getting a probe to 200 AU from the Sun 'as fast as possible' is what Innovative Interstellar Explorer is all about. The mission represents a current look at an idea that has been kicking around the space community for about thirty years now -- an interstellar precursor mission that would get us into the interstellar medium with an instrument package specifically designed for its study. The goals are laid out in a recent article in The Journal of Spacecraft and Rockets which has been made available online. The mission offers rich possibilities. At the top of the agenda is to explore the interstellar medium and study the properties of interstellar gas, the interstellar magnetic field, low-energy cosmic rays and interstellar dust. But the complex interactions between the Solar System and the space through which it travels are a major area for research as well. And learning more about the region immediately beyond the heliosphere can tell us much about the origin of the Solar System and...

Remembering Project Daedalus

by Paul Gilster | Dec 16, 2006 | Missions | 27 Comments

Centauri Dreams defers to no one in admiration of Project Daedalus, the 1970s-era starship design that emerged from the British Interplanetary Society. It's a pleasure to see continuing interest in the craft, as witness Alan Bellows' backgrounder about it on the Damn Interesting site. Daedalus was the first serious and thorough design for a starship, a robotic interstellar probe that would reach Barnard's Star in about fifty years, moving at twelve percent of the speed of light. Be sure to check the Bellows story for the overview. But let me fill in a little more background: The British Interplanetary Society, founded in 1933, used to meet regularly at London's Mason's Arms pub on Maddox Street, a setting that Arthur C. Clarke readers may recognize from his later collection Tales from the White Hart. Daedalus was designed by about a dozen scientists and engineers, many of its sessions occurring in pubs and similar venues. When I talked to Geoffrey Landis about Daedalus some years...

COROT Fueled and Ready

by Paul Gilster | Dec 6, 2006 | Missions | 7 Comments

The COROT satellite, slated for transit studies of nearby stars in search of exoplanets, has completed fueling up operations. Launch is scheduled for December 21 at the Baikonur cosmodrome in Kazakhstan. Nine days were required to top the satellite's tanks even though it is only carrying 40 litres of hydrazine, due to the highly poisonous nature of the fuel. A French project with ESA participation, COROT will be the first space misson specifically dedicated to finding extrasolar planets, and it may give us our first detection of rocky worlds only a few times larger than Earth.

Star Mission of a Lifetime

by Paul Gilster | Nov 28, 2006 | Culture and Society, Missions | 19 Comments

We seem to have accepted in our time the notion that technology always moves forward. But a key factor in the Drake Equation, that long and interesting conjecture that parses the possibilities for extraterrestrial life, is the question of whether technological societies have an average lifetime. Do they invariably survive to reach the stars, or do they destroy themselves before this is possible? Listen to something Fred Hoyle said back in 1964: It has often been said, if the human species fails to make a go of it here on Earth, some other species will take over the running. In a sense of developing high intelligence, this is not correct. We have, or will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology. This is a one-shot affair. If we fail, this planetary system fails so far as...

Barnard’s Star and the ‘Wait Equation’

by Paul Gilster | Nov 24, 2006 | Culture and Society, Missions | 26 Comments

When do you decide to launch a starship? It's a question based as much on cultural assumptions as technology. Start with the premise that we can ratchet up today's velocities to 150 kilometers per second, roughly ten times the speed at which New Horizons will cross Pluto's orbit. If we want to send a probe six light years to Barnard's Star at that speed, we would be looking at a travel time of 12,000 years. That's a lot of time, but better than Voyager's 70,000-year plus travel time to the Centauri stars (if either Voyager were pointed in their direction). Clearly, 12,000 years is too many, especially in an age that regards maximum mission time as the lifetime of a researcher working on the project. Besides, if we did launch that kind of mission, it would inevitably be passed enroute by a faster spacecraft. And that's the conundrum: does there ever come a time when you do launch, or are you always waiting for better propulsion systems and faster travel times? As Andrew Kennedy...

The Question of Arecibo

by Paul Gilster | Nov 17, 2006 | Asteroid and Comet Deflection, Missions, Research Tools | 6 Comments

The recent National Science Foundation report recommending scaling back support for the Arecibo radio telescope raises eyebrows here. Arecibo has just been instrumental in identifying the near-Earth asteroid 1999 KW4 as a binary, one that provides useful information about the mass, shape and density of its components and hence about near-Earth asteroids in general. That's the kind of knowledge we need as we ponder how to analyze Earth-crossing objects to prevent future planetary disasters. But while focusing on ongoing radio astronomy work, the report gives short shrift to Arecibo's radar capabilities, which make this kind of investigation possible. In a letter to the NSF's Division of Astronomical Sciences, Guy Consolmagno SJ, who is head of the Department for Planetary Sciences of the American Astronomical Society, had this to say: There is in fact only one reference to radar in the entire 78 page document, and no mention at all of asteroids. But the Arecibo radar results are key...

The New Worlds Starshade

by Paul Gilster | Nov 3, 2006 | Exoplanetary Science, Missions | 8 Comments

Finding planets around other stars is tricky enough, but actually getting images of them is all but impossible. That's why Centauri Dreams has been so fascinated with the starshade concept, and with one particular design for it, called (depending on the mission) New Worlds Discoverer, New Worlds Observer or New Worlds Imager. We saw recently that Webster Cash (University of Colorado at Boulder) had been pitching NASA to do a concept study on New Worlds for a Discovery-class mission, but the proposal didn't make the cut, in this round at least. That's disappointing, but as Cash told me in an interview earlier this year, "If we don't win this one, we'll win the next one." There is reason for such optimism because the New Worlds mission designs offer many of the benefits of the Terrestrial Planet Finder mission once slated for this kind of work at a fraction of the cost, and as I mentioned earlier this week, New Worlds has the potential of working with the James Webb Space Telescope to...

The Missing Discovery Mission

by Paul Gilster | Oct 31, 2006 | Exoplanetary Science, Missions | 0 Comments

Having championed Webster Cash's New Worlds Imager in earlier posts, Centauri Dreams was nonplussed yesterday to see NASA's list of concept study selections for Discovery-class missions. Chosen for further work and 1.2 million in funding each were an asteroid sample return mission, a Venus orbiter, and a mission to produce a gravity field map of the Moon. New Worlds Imager was nowhere in sight. NASA also chose three 'missions of opportunity,' meaning missions that can use existing spacecraft to produce new work. Out of these, the idea with most relevance to extrasolar work is Drake Deming's Extrasolar Planet Observations and Characterization (EPOCh), which would use the high-resolution camera on the Deep Impact spacecraft to look for Earth-sized worlds around other stars. Deming is a formidable player in the world of exoplanet detection (he was involved, for example, in the recent work on Upsilon Andromedae b) and we'll be keeping an eye on EPOCh. But we're also going to keep...

The FOCAL Mission: To the Sun’s Gravity Lens

by Paul Gilster | Aug 18, 2006 | Missions | 19 Comments

One of the great missions for the 21st century could be FOCAL -- a space probe sent to the Sun's gravity lens some 550 AU out. Gravitational lensing is becoming a major tool for astronomers, and we've even seen planetary detections using microlensing, looking at targets in the direction of galactic center and the faint changes in light that indicate a planet's passage. The gravity lens concept, harking back to a 1936 Einstein paper, came to the fore in 1978, when Dennis Walsh and team spotted a twin quasar image, the result of the lensing caused by an intervening galaxy as it bends light around it. So we know that lensing works. As far as I know, the first person to apply the notion to spacecraft was Von Eshleman (Stanford University), who considered a space probe to 550 AU to exploit the potential magnifications available there. And such missions have also been considered, by Frank Drake among others, as SETI experiments, using the Sun's ability to magnify the hydrogen line at 1420...

A Novel Strategy for Asteroid Deflection

by Paul Gilster | Aug 11, 2006 | Asteroid and Comet Deflection, Missions | 4 Comments

With the recent knowledge that half of all near-Earth asteroids are binaries, the stakes go up in the race to develop technologies to prevent potential impacts. But is the best solution what Centauri Dreams has always advocated, to intercept the approaching object as far from Earth as possible and alter its trajectory? A new paper suggests an alternative strategy: why not capture a nearby asteroid and put it into an Earth-bound orbit to use as a shield? Such an asteroid could then be moved as needed to absorb the impact of any collision that would otherwise hit the Earth. The work of Didier Massonnet and Benoît Meyssignac (Centre National d'Etudes Spatiales, France), the paper argues that an asteroid between 20 and 40 meters in diameter, which the two nickname 'David's stone,' could destroy a much larger incoming object under proper targeting conditions. The problem becomes finding the right asteroid. From the paper: We...have a detection challenge: we seek an asteroid small enough...

On Starshades and Planetary Threats

by Paul Gilster | Jul 12, 2006 | Culture and Society, Missions | 0 Comments

The possibility of deflecting an incoming asteroid became more problematic in early July. That's when David Polishook and Noah Brosch (both of Tel Aviv University) presented evidence that the number of binary asteroids near the Earth might be much higher than originally thought. Binaries might, in fact, comprise more than fifty percent of all NEAs. Now we're talking about moving two objects instead of just one, an indication that asteroid-nudging is more tricky than we thought. The paper "Many binaries among NEAs," available here, was presented at NASA's Near-Earth Object Detection, Characterization, and Threat Mitigation workhop in Colorado. It's a reminder that the environment incessantly nudges technological civilizations to extend their capabilities. Jose Garcia recently commented here on a story about the New Worlds Imager 'starshade' concept, noting that experience with starshades could come in handy in future attempts to mitigate the effects of global warming by covering up...

A Relativistic Probe to Alpha Centauri

by Paul Gilster | Jul 10, 2006 | Missions | 24 Comments

Good space science comes from unexpected quarters. When I interviewed the Jet Propulsion Laboratory's James Lesh about his thinking on communicating with a probe around Alpha Centauri, he pointed out how much can be gained by simply studying the signal sent by a spacecraft. Here in the Solar System, we've seen how that signal is affected by passing through a planetary atmosphere as the vehicle moves behind a distant world, an event that tells us much about the atmosphere in question. So in many cases it's not just the data carried by the communications signal, but how that signal behaves, that tells the tale. Can we imagine something similar around Alpha Centauri? Lesh envisaged a 20-watt laser communications system sending data from a sophisticated probe. But a new paper takes a different approach, imagining a fast probe moving at relativistic speeds, one that would announce its arrival in the Centauri system and create effects that could be studied from Earth. At 10 ounces, such a...

Cryopreservation: The Slow Way to Centauri

by Paul Gilster | Jun 22, 2006 | Culture and Society, Missions | 13 Comments

Slowing down the biological clock is one way to get to the stars. And it's a leading trope of science fiction, this idea that if we can't find faster ways to travel beyond our Solar System, we can at least shorten the journey for the crew, who will wake up decades (or centuries) after departure in orbit around their destination. Cryopreservation is one approach to slowing the clock, but it's always been plagued by the problem of tissue damage. For although some kinds of tissues can be frozen and revived, others succumb to damage from ice crystals that destroy the delicate structure of the cells. New work at the University of Helsinki, however, offers a sudden gleam of hope on the cryopreservation front. There, researcher Anatoli Bogdan has been working with a form of water called 'glassy water,' and in particular a form of it known as low-density amorphous ice. It's produced by supercooling diluted aqueous droplets, and it melts into what is known as highly viscous water (HVW). Let's...

Cutting Through Interstellar Dust

by Paul Gilster | Jun 9, 2006 | Interstellar Medium, Missions | 0 Comments

When the British Interplanetary Society's Daedalus designs were being created in the 1970s, the scientists and engineers involved quickly realized that interstellar dust would become a problem for a vehicle traveling at 12 percent of light speed. That led to shielding concepts involving materials like beryllium, boron and graphite. But what of concepts like Robert Forward's vast lightsails? If dust posed a problem to Daedalus on its way to Barnard's Star, surely a huge lightsail was even more threatened, there being no effective way to shield it. Forward himself suggested an answer in a 1986 letter to the Society's journal. His optimum sail materials (still far beyond our capabilities) would be much thinner than the diameter of the interstellar grains the starship would likely encounter. The result: such materials would pass right through the sail, creating a hole about as big as themselves. For work within the range of nearby stars, Forward believed, interstellar dust would not pose...

Reconstructing the Pioneer Anomaly

by Paul Gilster | Jun 3, 2006 | Exotic Physics, Missions, Outer Solar System | 11 Comments

New Scientist is running an interesting piece [subscription required for full access] on Slava Turyshev (JPL), who plans to investigate the so-called Pioneer Anomaly by re-flying the mission virtually. It's a fascinating tale for various reasons, not the least of which is how close we came to losing much if not all of the precious Pioneer data. For one thing, 400 reels of magnetic tapes housing information about the trajectories of the two spacecraft had to be saved from years of neglect and transferred to DVD. And that was just the beginning. When Turyshev visited NASA's Ames Research Center, his search for project records from the 114 onboard sensors that recorded the Pioneers' spin rate and other data turned up the floppy disks that mission engineer Larry Kellogg had saved. But Ames managers were close to destroying the disks because of lack of space. Having interceded to save this material, Turyshev then turned to programmer Viktor Toth to write a program to extract 40 gigabytes...

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In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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