HILO, Hawai'i — Lorna Onizuka, the widow of Hawai'i astronaut Ellison S. Onizuka, chooses her words carefully when she discusses the space program in the 20 years since her husband died in the Challenger space shuttle disaster. She speaks with a touch of disappointment.

Her visit to Hawai'i coincides with this morning's scheduled launch of the shuttle Discovery, which was to deliver German astronaut Thomas Reiter for a six-month stay on the International Space Station, and to test shuttle inspection techniques.

But the launch was to be only the second shuttle flight in three years, and the end of the shuttle program is on the horizon, in 2010. Onizuka refers to that date as the end of the "shuttle era."

"The International Space Station will be complete at that point, and there will be some science that will take place out until perhaps 2016 or so, but not at the level that we anticipated," Onizuka said.

"Part of it is the cost of exploration, pushing the boundaries and exploring things and places we never anticipated," she said. "But you know, you suffer losses, and with those losses, unfortunately, you end up with new constraints."

Onizuka, 56, is meeting family and old friends and serving as grand marshal in a Kailua, Kona, July Fourth parade today in honor of Ellison Onizuka. It is a homecoming for Lorna Onizuka, who was raised in Na'alehu, graduated from Ka'u High School in 1967, and met her husband while attending college in Colorado.

Air Force Lt. Col. Ellison Onizuka, who was born in Kealakekua, died along with five other astronauts and school teacher Christa McAuliffe when the Challenger exploded 73 seconds into flight on Jan. 28, 1986. After the disaster, Lorna Onizuka remained in Texas, where she found support in a close-knit circle of friends.

Onizuka spent part of her first day on O'ahu visiting her husband's grave at the National Memorial Cemetery of the Pacific at Punchbowl. She and her fiance, Leo Rudd, stopped in Hilo yesterday to put flowers at the grave of Onizuka's father, who died in 1994.

Onizuka now lives with her 82-year-old mother, Anna Yoshida, in the Houston suburb of Clear Lake City. Her grown daughters, Janelle and Darien, live nearby, and Onizuka works as executive consultant to JAXA, the Japan Space Agency.

She is also an agent with the NASA Multilateral Crew Operations Board, a panel of representatives from the partner agencies including the United States, Canada, Russia, Europe and Japan that screens and selects crew members nominated for specific space missions.

That work keeps her in close touch with space exploration. "Today's world is a whole lot different than when El used to fly," she said.

There is excitement over President Bush's plan to return to the moon and eventually reach Mars, but shuttle flights are kept to a bare minimum, particularly since the shuttle Columbia disintegrated on re-entry over Texas in 2003, killing its crew.

"I would like to see space stations be what they were anticipated to be. They were going to be a tremendous place for science to take place, and a lot of that is not going to happen," Onizuka said.

"I think we're doing the best that we can with the budget constraints that we have to deal with. I think that we're doing the best that we can with the orbiters that we have to fly with. It's not what I would see as the optimum way to go."

Onizuka's work brings her into contact with a new generation of astronauts and aspiring astronauts, and she's optimistic.

"We still have people that believe that without risk there is no new knowledge gained, and I think that is something that in spite of the loss of the crews that we have lost ... we still have people with that spirit, and this nation is fortunate to have those types of people."