Editor's note: Meg Urry is director of the Yale Center for Astronomy & Astrophysics and the chair of the Yale physics department. Her nearly three-decade career of space study includes a 14-year stint at the the Space Telescope Science Institute, the home of the Hubble Space Telescope, where she headed the Space Science Selection Office, sifting through thousands of applications from scientists each year hoping to use the telescope. This piece was written in association with The Op-Ed Project, an organization seeking to expand the range of opinion voices to include more women.
(CNN) -- Atlantis, the last space shuttle, returned to Earth on Thursday and will go to its post-retirement gig at the Kennedy Space Center Visitor Complex. After more than 30 years and 135 shuttle flights by literally hundreds of astronauts, NASA has reason to be proud.
But for any terrestrial mourners out there, I have some tissues and another perspective: It's time.
The shuttle is an aging workhorse that should be put to pasture -- it's time for a new direction for the space program.
The private sector should take over routine spaceflight while NASA develops new, more technologically current vehicles that can carry human explorers well beyond low Earth orbit.
Just as importantly, NASA should continue its wildly successful program of robotic space science, which has returned an incredible wealth of knowledge for pennies on the human-spaceflight dollar.
When Mercury, Gemini and Apollo rockets were launched in the 1960s, the country stopped to watch the launch. President Kennedy's ambitious goal of landing on the moon was achieved in eight years, by a NASA that was free to soar on a budget that rose to 4.4% of the annual federal budget in 1966, according to noted space historian John Logsdon. Doing my own math, I can compare that with today's NASA budget, which runs about 0.6%, or about $60 per American.
During that era of rapid innovation, lives were sacrificed -- by test pilots in space and Gemini astronauts on the ground -- but the space program moved ahead at light speed.
In the summer of 1969, almost 42 years ago to the day, the entire world was talking about Americans going to the moon. I was a child visiting tiny Meckesheim, Germany, where a childhood friend's father was on sabbatical. Everyone gathered at the one house with a TV set. When Neil Armstrong set foot on the moon, near dawn, a bottle of California (not French!) champagne was poured in celebration.
Then what had once transfixed the world became increasingly routine, especially after NASA successfully launched the space shuttle program. The shuttle was a big bus -- a reusable vehicle that could carry both cargo and people to low Earth orbit. In 135 flights, as the five space shuttles collectively circled the Earth more than 20,000 times, we learned about the physiology of humans in space and about the behavior of substances in near-weightless conditions.
Making spaceflight routine was a huge success for NASA. Now it's time to declare victory and move on.
NASA should be building sports cars, not buses -- cutting-edge vehicles that define a path toward our future in space. Private industry should take over routine spaceflight activities, with NASA as a customer.
NASA experts on human spaceflight should focus on the next frontier -- exploring asteroids, Mars, and beyond. Low Earth orbit? Been there, done that.
Space is about discovery -- the voyage, yes, but now, a destination beyond our near-Earth neighborhood. Yet after the moon missions in the 1960s, NASA was never funded to follow its ambitious vision for human spaceflight.
So what should we be doing in space? Here's the second critical point: Don't forget robotic space exploration, the other half of what NASA does.
Many Americans recognize the unsurpassed science and inspiration that have come from the Hubble Space Telescope over the past two decades, as well as from its less famous sister satellites like the Chandra X-ray Observatory, the Spitzer Space (Infrared) Telescope and the Fermi gamma-ray observatory. With robotic satellites exploring everything from the Earth, sun, and solar system (how about those Mars rovers!), to the farthest reaches of the universe, NASA has had one stunning success after the other.
NASA space science has taught us how the universe is expanding, how the stars and galaxies around us came to be, how planets form and how life might evolve in interstellar space. The list of top discoveries made with Hubble reads like the hit parade of astronomy: a mysterious new "dark energy" causing the accelerating expansion of the universe, distances to other galaxies, the supermassive black holes at their centers, the age of the universe, planet formation around other stars, searches for signs of extraterrestrial life -- and the list goes on.
These NASA achievements are our pyramids at Giza, and the knowledge they bring is our library at Alexandria.
And space science is relatively cheap. One look at the NASA budgets will tell you: 20 years of Hubble -- including all the research done by thousands of scientists across the country -- costs about the same as one year of shuttle operations.
Saying goodbye to the shuttle isn't saying so long to space. It's time to turn to the future. Hubble's successor, the James Webb Space Telescope -- designed to reveal the first galaxies ever formed in the universe and to study other planetary systems -- could far surpass Hubble's discoveries. It doesn't get any cooler than that.
The opinions expressed in this commentary are solely those of Meg Urry.