Jon Morse, the chief executive of the BoldlyGo Institute, one of two nonprofits leading the consortium, called it “the holy grail of exoplanet research.” If there is a “pale blue dot” — a world covered in oceans — at Alpha Centauri, the telescope would permit scientists to study it in detail, looking for signs of life in the light reflected off the atmosphere.
To be built by the end of the decade, the telescope is the type of mission that NASA rarely undertakes, experts noted: tightly focused and cheap, leading to momentous discoveries — or possibly nothing at all.
The two stars of the Alpha Centauri system are both similar to the sun, the closest such stars at 4.37 light-years away. The proposed telescope, with a mirror only about 20 inches across, would be able to make out Earth-size planets orbiting in the stars’ so-called habitable zone, where temperatures are warm enough for liquid water to flow at the surface and, hypothetically, for life to thrive.
NASA’s Kepler mission has discovered a multitude of Earth-size planets in the galaxy, and in August astronomers using ground-based telescopes announced the discovery of a potentially habitable planet around Proxima Centauri, our closest neighbor at a distance of 4.22 light-years.
But Proxima Centauri is much smaller and dimmer than our sun, and the planet, even if similar in size to Earth, would not be particularly Earthlike. It orbits much closer to the star, likely with one side perpetually in daylight and the other eternally dark. Because the planet is so close to its star, the proposed telescope would not be able to study it.
So far, most exoplanets have been discovered indirectly, deduced by slight perturbations in the light traveling from a star — by a slight dimming when the exoplanet passes between its star and Earth, or by wobbles in the light’s wavelengths caused by the gravitational pull of an unseen exoplanet.
If astronomers could photograph a planet directly, they could start to look for specific wavelengths of light that serve as fingerprints of specific molecules. Detection of oxygen in the atmosphere would argue for photosynthesis and plants, for example.
Dr. Morse said the proposed telescope, called Project Blue, would most likely cost $25 million to $50 million, perhaps one-third the cost of a NASA mission with similar goals. That is still a lot of money, and not easily raised.
Crowdfunding through small individual donations might cover some of the early design work, he said, but “we do have to approach high-net-worth individuals and foundations.” Participating institutions, like the SETI Institute and the University of Massachusetts Lowell, could also offer in-kind contributions to the project rather than cash.
The idea of a telescope pointed at Alpha Centauri is not new. Ruslan Belikov, a scientist at NASA’s Ames Research Center in Mountain View, Calif., has been working for years as principal investigator on the Alpha Centauri Exoplanet Satellite, or ACESat, developing the technology needed to pick out planets in a binary star system.
The ACESat project has not won NASA approval, however. Eduardo Bendek, ACESat’s deputy principal investigator, estimated that there was a 15 percent chance that there are no planets in the habitable zones of the two Alpha Centauri stars. “NASA is very averse to that risk,” he said.
To reduce the chances of discovering nothing, the ACESat team proposed a mission that would examine not just Alpha Centauri but also a few other nearby stars. But expanding the mission — plus other considerations to reduce risks — increased the price tag.
Dr. Belikov and Dr. Bendek declined to provided specific figures, but said the total budget fit under the required $175 million cost cap when they submitted the proposal to NASA’s Small Explorer astrophysics program in 2014.
Instead, NASA selected three other missions for further study. ACESat remains unbuilt, and the next opportunity to submit a proposal is most likely in 2019, Dr. Belikov and Dr. Bendek said.
“I can’t speak for NASA,” Dr. Beikov said, “but speaking personally, I’m excited about the possibility of doing space missions privately.”
So far, privately financed space missions have met with limited success. Competitors in the Google Lunar X Prize, to send the first private spacecraft to the moon, have had trouble finding backers. Planetary Resources, a Seattle company aiming to mine asteroids, withdrew a plan for a crowdfunded space telescope, sending back contributions collected on Kickstarter.
Another project, Lunar Mission One, intended to send a robotic lander to the moon’s south pole, successfully raised about $1 million via Kickstarter, but probably needs more than 600 times as much to pull it off.
BoldlyGo is also pursuing two more ambitious projects — a larger space telescope, and a spacecraft to collect samples from the Martian atmosphere and bring them back to Earth — that have not yet gotten off the ground.
Dr. Morse, who once ran NASA’s astrophysics division, agrees that Project Blue will not be easy, but says it is possible. For more than a century, he notes, astronomers have relied on the generosity of rich benefactors.
“All we’re doing is borrowing the model that ground-based astronomy has been using literally since the time of John Quincy Adams,” Dr. Morse said. “We think that quest is worthy, and we’re going to try to do it with private funding.”
By KENNETH CHANG - nytimes.com