Editor's note: Meg Urry is the Israel Munson professor of physics and astronomy and chairwoman of the department of physics at Yale University. She is also the director of the Yale Center for Astronomy and Astrophysics. She previously worked as a senior astronomer at the Space Telescope Science Institute, which runs the Hubble Space Telescope for NASA. 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) -- Nearly everyone I meet has heard of the Hubble Space Telescope. Many have seen its beautiful images of the birthplace of new stars and planetary systems, or of the "gravitational lenses" that reveal a mysterious "dark matter" that dwarfs the amount of matter bound up in stars or galaxies.
This year's Nobel Prize in physics went to three scientists who used Hubble to detect the mysterious dark energy -- a sort of fifth fundamental force, previously unknown -- that we now think is causing the accelerated expansion of the universe.
Hubble pictures and the knowledge the HST generates have changed our view of the cosmos and reached nearly every schoolchild in America.
Hubble passed its 20th birthday last year -- young on a human time scale, but pretty elderly for a working spacecraft. Although frequent "body transplants" -- that is, the installation of new cameras and other systems -- keep Hubble acting like a teenager, it will reach the end of its useful lifetime by the end of the decade. What happens after Hubble takes its last picture?
A decade ago, the astronomy and astrophysics community recommended as its very highest priority the James Webb Space Telescope to succeed Hubble. It will be a 6.5-meter foldable telescope -- roughly the size of a typical classroom, and more than six times the area of the Hubble mirror. It is named after James E. Webb, who ran NASA from February 1961 to October 1968, a time of incredible scientific innovation and the Apollo moon program. The telescope named after him will answer new questions far beyond the capabilities of Hubble.
For example, JWST will look for signs of carbon-based life in the atmospheres of planets around other stars. The discovery of life elsewhere in our galaxy would be as mind-blowing as NASA's Apollo-era picture of the "Earth-rise" as seen from the moon.
JWST will measure where and how chemical elements forged within stars were dispersed into space -- the same carbon, oxygen and other elements that eventually formed our Earth and became (literally) part of us.
Because of its large foldable mirror, enormous solar shade and cryogenically cooled cameras, JWST will be able to see the very faint light from the very distant first galaxies, which formed 13 billion years ago, and perhaps the super explosions of the first stars formed in our universe.
Astronomy works a bit like archaeology, in that we directly observe the past. This is because light from the very distant universe takes billions of years to travel to our telescopes. So by observing the most distant galaxies, we can understand how galaxies formed and evolved to the present day.
There are also very practical reasons to care about such discoveries. Astronomy is a gateway science, attracting young minds. Astronomical instruments like Hubble and JWST push technical frontiers, developing new technologies that have other applications.
Last July, in a difficult budget environment, the House zeroed NASA's budget for the JWST project. Three weeks ago, Congress restored JWST funding for this fiscal year but warned that its budget and schedule milestones would be closely monitored.
The cost over two decades is $8.8 billion dollars, including five years of operation, with nearly half already spent for technology development and construction. On Tuesday, the House Science, Space, and Technology Committee will hold a hearing at which leading scientists and JWST program managers will describe the scientific grasp of this advanced telescope and how the replanned mission can be achieved on time and within a strict cost cap.
In this fiscal environment, tough choices have to be made about which important and valuable government programs are not affordable. Each decade, the astronomical community sets priorities among many worthy projects competing for very limited dollars.
The 2001 survey, "Astronomy for the New Millennium," named a space infrared telescope like the JWST as the No. 1 priority. NASA started the JWST project soon after, with Canada and Europe as partners, and now 70% of the telescope is already made or in fabrication. The next report, in 2010, "New Worlds, New Horizons," described the essential role of JWST across the scientific landscape, from the "cosmic dawn" of stars and galaxies to the development of life on planets outside our solar system.
With a flagship mission like JWST, the U.S. can continue its international leadership in science and technology. Other countries like China and India are investing substantially in these areas, and a larger fraction of their college students major in science and engineering. Failing to complete JWST would disappoint our international partners and send a strong signal to the world that the U.S. is stepping back from forefront science.
Scientific discovery is not a luxury. Fundamental physics discoveries from early in the 20th century contribute greatly to our national economy, according to "Gathering Storm," the National Academies' report that warned that U.S. science, technology, engineering and mathematics need to be bolstered to ensure an good economic future. Even in a time of fiscal austerity, the U.S. needs this next-generation space telescope.
It is remarkable that from just a few hundred years of observing other stars and galaxies, astronomers have figured out billions of years of history. With JWST, we can push to greater distances and thus farther back in time.
Astronomical discoveries feed the fundamental curiosity of humans about how we got here, where we are going, and whether there is life beyond Earth. They add to the edifice of knowledge that is our legacy as humans. Hubble made incredible advances. With JWST the nation will go much further.
The opinions expressed in this commentary are solely those of Meg Urry.