The University of Hawaii is proposing another cutting-edge mountaintop astronomy facility — this time the world’s highest-contrast optical telescope — but instead of creating a new imposing structure like the Thirty Meter Telescope or the Inouye solar telescope, it would simply replace an old one.

The proposed $4 million PLANETS telescope, billed as the world’s most innovative and powerful instrument designed to study the atmospheres of planets, including those around other stars, is small enough to fit snugly into an existing structure that was formerly the University of Chicago Cosmic Ray Neutron Monitor Station on the Haleakala summit on Maui.

The university last month issued a finding of no significant impact for the PLANETS (Polarized Light From Atmospheres of Nearby Extra-Terrestrial Systems) telescope after publishing a draft environmental assessment last summer.

Because no new building would be required, the facility doesn’t appear to carry the same kind of controversy that plagued the state’s recent astronomy projects; but it could run into resistance nevertheless.

Kahele Dukelow of Kako‘o Haleakala, the group that organized last year’s opposition to the 140-foot-tall Daniel K. Inouye Solar Telescope under construction on Maui’s 10,000-foot summit, said Monday she disapproves of the effort.

“The continued presence is a desecration,” said Dukelow, assistant professor of Hawaiian studies and language at University of Hawaii Maui College.

Hundreds of people last year blocked a wide-load delivery of parts and components to the yet-to-be-completed $340 million Inouye solar telescope, and 20 were arrested in an unsuccessful attempt to prevent another delivery.

The civil disobedience was inspired by the Hawaii island protests that blocked crews from reaching the $1.4 billion Thirty Meter Telescope construction site near the top of Mauna Kea that year.

UH officials say the PLANETS telescope will require no wide-load deliveries.

The proposal, they said, will feature a thin, 1.85-meter mirror specifically designed to fit within an existing 1,619-square-foot facility with minimal alterations, reducing potential impacts to environmental and cultural resources.

The existing structure is so small it is dwarfed by neighboring observatories.

“It literally can’t be seen from outside Puu Kolekole,”said Mike Maberry, assistant director of UH’s Institute for Astronomy. Puu Kolekole is the home of the Haleakala High Altitude Observatories Site, sometimes called Science City.

Despite its diminutive size and relatively low cost, the PLANETS telescope would offer “unprecedented scientific capabilities” and “the potential to lead to discoveries in areas related to exoplanet detection, circumstellar environments, and extrasolar planetary atmospheres,” according to its environmental assessment.

“No other telescopes currently exist that have these capabilities and are able to provide such a high level of contrast in low scattered light and during nighttime,” it says.

The telescope is actually a prototype designed to test new, relatively low-cost technologies and techniques that will eventually be used as the basis for the largest telescope in the world, the 74-meter Colossus, which is planned to be built in Chile.

The PLANETS Foundation — with partners that include the Institute for Astronomy at Tohoku University in Japan, the Kiepenheuer Institute for Solar Physics in Germany and the National Autonomous University of Mexico — aims to prove it’s possible to find life outside our solar system by the end of the decade.

UH astronomer and project leader Jeff Kuhn said PLANET’s thin “off-axis” mirror would be able to see the faint atmospheres of Mercury and of Jupiter’s Io moon, and enable optical studies of a small handful of the nearest and largest gas giant exoplanets.

If everything goes well, Kuhn said, the foundation will use the same technology to build ELF, or Exolife Finder, combining 16 larger PLANETS mirrors, 5 meters in size, into a hybrid telescope with the sensitivity to see alien oceans and continents on nearby Proxima Centauri b exoplanet using a technique called rotational exoplanet imaging.

If that goes to plan, he said, Colossus will be next, featuring 58 8-meter window glass-thin mirrors that will be combined to enable a “census of life on a few hundred of the nearest habitable-zone exoplanets.”

Expenses for Colossus will be reduced by a factor of 10, in part because the mirrors will be created using 3-D printing, Kuhn said.

If Colossus is a success, an array of Colossus-size telescopes could combine to go even deeper to find life in the universe, he said.

Kuhn said Colossus is at least a decade from becoming reality.

For now the PLANETS telescope would be fitted into a building that was constructed in the mid-1950s as one of the earliest astronomical observatories on Haleakala. It was known as the Baker-Nunn facility, which was part of Project Vanguard, one of the nation’s earliest satellite tracking programs.

In 1991 the University of Chicago Cosmic Ray Neutron Monitor Station took over to expand its network of high-altitude neutron monitor stations. Discontinued in 2004, it has been used since then for storage and personnel quarters.

Under the PLANETS proposal, the flat portion of the existing roof would be removed and replaced with a roll-off enclosure less than 7 feet taller than the highest point of the existing roof.

The roll top would allow the roof to roll back and the telescope to be raised for the best observation without a permanently taller structure. Rails and posts for the roof frame would extend an additional 23 feet from the structure, while the frame would remain within the existing concrete slab.

The telescope would be operated remotely, with no on-site personnel required. About once a week a crew member or visiting scientist would visit the site to service or manipulate the instrumentation.

According to the environmental document, the telescope would provide educational opportunities in astronomy and science for local schools.

The university is now seeking a conservation district use permit, allowing it to launch two years of work, including four months of construction, with a target operational date of January 2019.