Astronomers hope to build a cluster of four small "outrigger" telescopes on the fringes of the two matched Keck 33-foot mirror telescopes atop Mauna Kea, with the goal of using their combined power to develop images of large planets around distant stars.
Just a few years ago, the Holy Grail of astronomy was proving that planets even existed around stars other than our own sun. Measurements of the wobble of stars, caused by the gravitational fields of their orbiting planets, have resolved that issue.
Next is the challenge of trying to obtain an image of such a planet, trillions of miles away. The Keck telescopes, their light combined in a technique called interferometry, may be able to do that.
"We should be able to build images of hot, Jupiter-sized planets" around distant stars, said James Beletic, physicist and deputy director of the W.M Keck Observatory, whose offices are in Waimea on Hawai‘i. The new outrigger project is to be paid for by NASA.
But before construction can begin on the outrigger telescopes, each of which would have a 6-foot mirror, the astronomy community will need to deal with issues on the ground, primarily the cultural significance of features atop Mauna Kea and the impact of construction on the unique biological life there.
The state Historic Preservation Division feels the continued construction of astronomy facilities atop Mauna Kea will adversely impact the historic qualities of the mountain.
Historic Preservation administrator Don Hibbard said his office’s research suggests the Keck telescopes, on a cinder cone called Pu‘uhau‘oki, are part of a Mauna Kea summit complex known in ancient times as Kukahau‘ula. This region was named after a legendary Hawaiian figure and deity who was the husband of the Poli‘ahu, the snow goddess of the summit, and in other stories the husband of Lilinoe, the companion or sister of Poli‘ahu. The names of all three are closely associated with features near the summit of Mauna Kea.
While surveys of Pu‘uhau‘oki itself have not located burials or archaeological remains, the region clearly has cultural significance, he said. Hibbard said the summit region, some of which is occupied by telescopes, is probably eligible for placement on the National Register of Historic Places as a historic district.
He did not oppose the development of the Keck outriggers, but said restrictions should be established to prevent deterioration in the shape and contour of the Pu‘uhau‘oki cinder cones and crater. Archaeologists, too, should oversee construction to ensure any possible burials are properly cared for, he said.
The Office of Hawaiian Affairs also expressed concerns on a variety of grounds.
"Our concerns are always for the historic sites and the sacredness of the area," said Jalna Keala of the OHA Hawaiian Rights Office.
In its official response to the project, OHA called for extended consultation with the Hawaiian community and said NASA should do more to address the concerns of Hawaiians.
Biologically, one of the most interesting known creatures atop the 13,796-foot mountain is the wekiu bug, which lives in the cinders and is a candidate for the federal endangered species list. This quarter-inch-long insect eats the bodies of other insects blown upslope from the lower reaches of the volcano, and it has a kind of natural antifreeze that prevents it from icing up in the frigid summit conditions.
Previous astronomy facilities have damaged some of the cinder cover that wekiu require, and the Keck project proposes to restore one damaged area with the kind of sifted, washed cinder believed to be what wekiu need.
Most of the outrigger telescope work will be on land already bulldozed flat, but about 2,000 square feet of wekiu habitat would be damaged. To make up for that, the project proposes to restore 6,000 square feet of already damaged habitat in the Pu‘uhau‘oki crater floor nearby.
Scientists hope the wekiu will populate the restored habitat from surrounding areas.
"We’ve been working with Caltech (a partner in the Keck Observatory) and NASA (which would fund the outrigger telescopes) and feel pretty good about their mitigation measures," said Mike Richardson, an entomologist and invertebrate recovery coordinator with the Fish and Wildlife Service’s Pacific Islands Ecoregion Office.
The Mauna Kea summit also contains unique native wolf spiders and moths, but their populations are more broadly scattered than the wekiu
, whose range is limited to the same region of the summit that is occupied by the astronomy facilities.
Barring problems, the permit processes for the outrigger telescopes could be complete this summer, and construction could begin as early as late summer, astronomy officials said.
The Keck telescopes can operate independently. When the two large Keck telescopes are linked, they will be called the Keck-Keck Interferometer. When the outriggers are added to one or both large telescopes, they form the Keck Interferometric Array.
The proposed outriggers are situated on the same flat, bulldozed pad as the Keck telescopes, forming a small constellation around the big Kecks. While the two big Kecks are about 260 feet apart, the outermost outriggers are about 340 feet apart.
All the telescopes will be connected by underground tunnels, which will take the light beams gathered by the mirrors and bring it to a central underground room. In effect, a series of small scattered telescopes connected in this way can gain images with the clarity of a telescope with a mirror as large as the distance between the small ones.
NASA is financing the Keck outriggers as part of its Origins program, which is aimed at understanding the origin of the universe and seeking out other planets that might be able to support life.
"The ultimate goal in all of this," Beletic said, "is to find other planets in other solar systems, and ultimately, to find life."
