Bob Grossfeld, observatory manager, adjusts a telescope in the new addition at the Sunriver Nature Center & Observatory on Friday, Sept. 24, 2021.

BEND — The Oregon Observatory at the Sunriver Nature Center already has the most telescopes available for public viewing in the United States, but now it has more space for other attractions.

A major expansion of the NASA-affiliated observatory was completed last week, and visitors have been able to enjoy more room and shorter waits to use six new telescope locations.

“Even before we did the expansion, we were the largest public viewing facility in the country,” said Bob Grossfeld, observatory manager. “Now we expanded that capability and allowed for people to have more space to move around and look at telescopes.”

The expansion is the first phase in a $5 million upgrade of the nature center.

The second phase is scheduled to start in 2023. It will feature a 7,700-square-foot Discovery Center that will include a planetarium theater with a full projection system and seating for up to 94 visitors. The center also will build an 1,800-square-foot pavilion on the back of Lake Aspen.

Abby Rowland, executive director of the nature center, said more than $2.5 million has been raised so far through donations and grants, enough to complete the first phase and plan for the future developments.

“The whole purpose for the campaign is to broaden our reach and to serve as a platform for science education,” Rowland said. “Having the newly expanded observatory starts us on the path for that.”

Rowland said the nature center has outgrown its campus. The nature center and observatory were built in 1984 and designed to accommodate 5,000 to 10,000 visitors each year. But the number of visitors has increased to about 50,000 annually.

Prior to the COVID-19 pandemic, the observatory would draw about 400 people on busy nights.

Rowland expects to see those numbers return next summer, the peak season at the observatory.

A recent designation from the International Dark-Sky Association also is expected to bring more visitors to the observatory, Rowland said. The association named Sunriver a Dark Sky Friendly Development of Distinction, one of about 170 distinctions across the world.

The expanded observatory will be able to welcome the growing number of visitors, including those drawn there because of the Dark Sky designation, Rowland said.

“We are growing into our reputation,” she said.

The expanded observatory will host a private grand opening Tuesday, Sept. 28, for the donors involved in the project. Most of the walls in the new space remain bare, but the observatory staff has several plans for new exhibits.

Grossfeld said a meteorite exhibit in the nature center will move to the expanded observatory, and future exhibits will feature rockets and antique telescopes.

“There’s a lot more exhibit space out there than we ever had before,” Grossfeld said. “We have a bunch of blank walls to play with to put hands-on exhibits and some informational exhibits.”

A motivation for expanding the observatory was to welcome more grade school field trips and university research teams, Grossfeld said. The pandemic canceled most field trip opportunities this year, but Grossfeld is looking forward to working with students in the future.

“We expect that to go back to normal,” Grossfeld said. “Hopefully sooner rather than later.”