Washingtonians joined people across the country Sunday night in assembling for the expected culmination of a flight across millions of miles of space to a landing on Mars.

Harold Alden Williams decided to open the planetarium at Montgomery College in Takoma Park so people could join as a group in learning the outcome of the effort to place a Mars rover named Curiosity onto the surface of the Red Planet.

After a flight of eight months, the planetary rover, designed to make an unprecedented search for Martian secrets, was expected to touch down l about 1:30 a.m. Monday.

College facilities do not regularly remain open at that hour, but this was a climactic moment in recent space exploration.

“I was convinced it was a good thing to do,” Williams, the planetarium’s director, said Sunday night. It’s “a really exciting landing,” he said. “A marvel.”

Montgomery County resident Martin Gottschalk thought he should attend. As a boy, he stayed up late to watch live coverage of the Apollo missions to the moon. This, the patent examiner said, “is not quite like that, but it’s almost like that.”

Gottschalk said he was not certain how much data would be available Monday morning. But, he said, he hoped there would be a signal indicating that the severe problems of successful descent onto the Martian surface had been overcome.

“Hopefully,” he said, “we’ll cheer.”

District resident Brad Barr said he and a few friends were also headed for the Takoma Park facility.

“I hope Curiosity lands,” he said. “I hope everything is fine.”

A gathering was also scheduled for NASA’s Goddard Space Flight Center in Greenbelt. A spokesman said it was arranged for the visitors’ center, which can hold more than 300 people.

All reservations had been taken days ago, authorities said.

As of early Monday it appeared that the complex mission, the product of years of painstaking planning, had paid off.

A few seconds before 1:33 a.m. the space agency posted the news on one of its web sites: “NASA's Curiosity rover has landed on Mars!”

Along with the hopes of many in t he space community, it appeared that the determination of scores of Washington residents to sacrifice sleep had been rewarded.

While on Mars, the rover and the mobile science laboratory sent with it are to search for clues as to whether the planet had ever been capable of sustaining life.

Goddard has created on-board instruments for the lab, the space flight center spokesman said.

(This report has been updated)