One of America's significant space achievements is a quarter-century old and still sending rewards back to Earth. The Hubble Space Telescope, launched 25 years ago this month, has brought more discoveries than NASA can count. Thanks to its deep space images and data, scientists know more about our planet's origin, our solar system's vast size and our universe's breathtaking beauty.

For example, the telescope's observations helped researchers determine that the universe's expansion is accelerating rather than slowing. It also shows that supermassive black holes lurk at the heart of most galaxies, and maybe all of them. Just as importantly the bus-size telescope orbiting since April 24, 1990 also opens the astonishing wonder of the cosmos for non-scientists in a way that no other spacecraft has, mission leaders say.

"The universe is so much more accessible now to everyone than it had ever been before Hubble was launched," says Ken Sembach, head of the Hubble Mission Office at the Space Telescope Science Institute in Baltimore. "That's the lasting legacy." The telescope has been reborn again and again over the last 25 years, thanks to maintenance by astronauts until 2009, when space shuttle flights ended. Crews replaced circuit boards, did computer repairs and replaced optical parts such as lenses. Even without more hands-on fixes, Hubble works so well that NASA plans a 30th-anniversary celebration in 2020.

Ex-astronaut says: "This is a celebration partly about the telescope and partly about NASA, but much of it is a celebration of people doing science." – John Grunsfeld, associate NASA administrator

Science columnist says: "After a quarter-century, the telescope's future and promise are still as big as the sky and our ignorance of what lies behind it." – Dennis Overbye, New York Times reporter narrating the video below

What’s ahead: The James Webb Space Telescope is scheduled for launch in 2018.