Posted on 06/25/2002 10:30:16 AM PDT by RightWhale
Astronomers on Brink of Watershed in Planet Discoveries
By Robert Roy Britt Senior Science Writer
posted: 07:00 am ET 24 June 2002
WASHINGTON, D.C. - The first phase of a two-decade hunt for planets around other stars ended this month with announcements of the discovery of two planets in Jupiter-like orbits, proving that our solar system has cousins, at least of the distant variety.
Now it is census time. The world's top planet hunters are rushing headlong into Phase II, during which they expect the number of known extrasolar planets to rise dramatically from its present total of about 100. Several groups are fanning out in all manner of observational directions, with telescopes big and small, to root out, count and characterize other solar systems.
Based on interviews with top experts, the new era will probably last anywhere from four to six years, barring any major surprises. It may be the least glamorous of the three phases outlined by astronomers, but it is a necessary prelude to the holy grail of planet hunting: Phase III, the discovery of Earth-like planets.
This phase would begin if and when the first rocky planets are detected, places that would resemble Earth, places where liquid water exists on the surface and the temperature is conducive to life.
"That'll be the real breakthrough, when you find things that you'd actually like to own real estate on," said David Latham of the Harvard-Smithsonian Center for Astrophysics.
While Phase I and II are being conducted from the ground, Phase III must wait for a new generation of space-based telescopes to be built. Last week, Latham and other top planet hunters gathered at the Carnegie Institution here to assess the status and future of their burgeoning profession.
Phase II: The Watershed
For now, technology limits discoveries to large, gaseous planets. All have been found by a creative method that notes the wobble of a star caused by the gravitational tug of an orbiting planet.
A new approach, which involves watching a planet eclipse the light of a star, shows imminent promise.
Two research teams have already used this so-called transit method to find "potential planet candidates." The first were announced by the Optical Gravitational Lensing Experiment (OGLE) team in February. The European group found 42 candidates among the millions of stars they monitored.
On Thursday, Princeton University's Gabriela Mallen-Ornelas said her EXtra-solar PLanet Occultation Research (EXPLORE) project had identified three and possibly four candidates in a survey of 38,000 stars.
With both these projects, some of the objects will likely turn out to be companion stars, instead of gas giant planets. The astronomers say they are very close to telling the difference as they refine their methods and determine how to use other telescopes for follow-up observations.
Other researchers agree there is a good chance some of these candidates will indeed be planets.
"We are on the brink of the first discovery of a planet by the transit method," Latham said. "And then I think you'll find it's a watershed. They'll start to come fast and furious. You'll see dozens of them."
Latham expects the first announcement by year's end. He told SPACE.com he would be disappointed if it did not come within 12 months. He said several other groups have completed observations of various star fields, but unlike the OGLE and EXPLORE teams they're just beginning to analyze their data and do follow-up work.
Complimentary approaches
The transit method brings two important advantages to the search. While the wobble method typically involves surveys of 2,000 stars or less, the transit technique can survey tens of thousands or millions of stars at one time. Further, the wobble method works best for Sun-like stars, whereas transits can be spotted around other, hotter stars.
Using both approaches, astronomers expect to find enough gas giants in the near future to begin making judgements about just how common solar system formation is and how often it resembles what happened around our Sun.
The wobble scientists have several more possible Jupiters in their data already but are waiting for each of the objects to make a compete orbit before it is announced. The orbits can take 10-15 years -- roughly equal to how long the researchers have been collecting data on many of the stars.
"What will be very exciting in the next couple of years is for other Jupiter-like planets to turn up," said Caltech's David Charbonneau, who last year led a team that made the first detection of an atmosphere of a planet around another star. "Then we'll learn what the rate of occurrence is of those Jupiter analogues. Is it 50 percent? Is it 10 percent? Or is it very rare?"
Jupiter-like planets are considered important in part because they shield inner planets, like Earth, by absorbing comets and asteroids that might otherwise routinely hit and sterilize the smaller worlds.
Phase III: Other Earths
Almost no one expects a true Earth-like planet to be found until at least the end of the decade.
NASA's Kepler mission, slated to launch in 2007, will survey about 100,000 stars continuously for four years, looking for transiting planets. The mission could detect some rocky planets orbiting very close to their host stars in the early months, because the planets would orbit frequently.
Such a finding would signal the beginning of Phase III, proving that Earth-like planets, at least in some form, can develop around other stars.
But a potentially habitable planet in an Earth-like orbit would take roughly one year to complete a full trip around its star. If one is spotted, it would not be announced until it had been observed on multiple passes, said William Borucki, who leads the mission. Borucki told SPACE.com that if Kepler detects a possible Earth-like planet, his team will want to be sure about it, and so the data would not be released until late in the mission, probably 2010 or later.
Kepler is designed to create a census of terrestrial planets in one patch of sky.
If Earth-like planets are common, Borucki said Kepler could be expected to find up to 500 of them. He notes that we might then assume life could be prevalent throughout the galaxy. If Kepler finds few or none, scientists would infer we are more likely to be rather alone.
Earlier opportunities
A French mission to find terrestrial planets, called COROT , will launch in late 2005 and has a chance of stealing some of Kepler's thunder. COROT researchers, if they are fortunate, could announce the first extrasolar terrestrial planet in 2006, COROT scientist Claire Moutou said in an interview.
But for COROT to spot a terrestrial, the planet will have to orbit very close to its host star. COROT will not be able to spot Earth-sized planets in Earth-like orbits.
A Canadian project, being done on a shoestring budget of about $10 million, has a long-shot chance of finding a terrestrial planet much sooner, said Latham, the Harvard-Smithsonian researcher.
The Microvariability & Oscillations of STars (MOST), due to go up this October, will be the smallest space telescope ever launched -- about size of a pie plate.
"They aren't going to look at very many stars, but they're going to look at them with much better photometric precision and monitoring duration than is possible from the ground," Latham said. "And they might get lucky."
Luck, as any astronomer knows, is part of the game. But so is hard work and creativity -- something that the planet hunting community is getting a lot more of as the relatively new field gains steam.
"This field has exploded so dramatically and has attracted so many people, especially young people, that we have all kinds of new ideas," Latham said. "The richness of the new ideas means that all kinds of discoveries could happen [including things] that I'm not even thinking of today because I'm an old guy."
"They" will never let us own real estate anywhere. Just a bundle of rights. Only kings can own land. Citizens -- never.
As to the search for life: If life is found, then fine. The search for life is not a worthy task however, nor is discovery of life a proper goal.
If life is found, then fine.
That would upset some "apple carts", especially if intelligent life is found. But fear not, prime-health biologic immortality here on Earth will be achieved and that will surely disrupt the heavens' apple carts.
Can't think of anything that wouldn't change.
There's an economic reason for this, though. Ordinary citizens will never be able to drive themselves to these planets. They'll rely instead on some entity with sufficient funds to put them on-location.
He who controls the transport, controls the land.
A Catholic priest said a few years ago that it would not affect his religion. Maybe some religions would be greatly affected. Others maybe not at all.
Today the books, tomorrow the periodicals, next week the universe.
Well said. Discovering the secrets of the physical universe is worthy in it's own right.
That said, others on this thread have wondered what the theological implications will be if life is ever found elsewhere. I wonder what the implications will be to them if it isn't?
Hey, I ran across this, thought you might like it....
None, because they'll never acknowledge that it doesn't exist. They'll simply claim that we "haven't found it yet."
For proof of this assertion, talk to any SETI enthusiast.
And that would be a fair assertion, since I couldn't disprove it.
However, one of the things I like about SETI research is that it seems to indicate that Solar Systems and Earth-like planets aren't all that plentiful. Von Daniken and Sagan acolytes have little to hang their cloaks on.
And think that is a good thing??
Yeah, I happen to think that the Earth is a unique and special place in the Universe. I think Life is exeptionally rare, perhaps non-existent elsewhere.
All presumptions, I know, but I like it when the hard data seems to bear my opinions out.
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