The festival's opening ceremonies were held at Battery Park, where a giant life-sized model of the observatory will be displayed all week for the public to see.
The World Science Festival will include science-themed lectures and events throughout the city from June 2 through June 6. A gala performance on Wednesday featuring Alan Alda, John Lithgow, Yo-Yo Ma and other celebrities will honor physicist Stephen Hawking.
Next generation space telescope
The $5 billion James Webb observatory, envisioned as the successor to the Hubble Space Telescope, will launch in 2014 to scan the skies in infrared light. Scientists hope it will reveal some of the youngest galaxies in the farthest reaches of space, helping to solve some fundamental cosmic mysteries such as how the universe formed.
The mockup, built by prime contractor Northrop Grumman Aerospace Systems, stands 40 feet (12 meters) tall, with a heat shield the size of a tennis court.
"It's really thrilling – it makes it so tangible that we can really do these things," Greene told SPACE.com.
Also on hand at the ceremonies was NASA's deputy administrator Lori Garver, who said she hoped James Webb's appearance in New York might help to build its image as a future space observatory.
"Everyone's very excited for this telescope to launch," Garver told SPACE.com. "I think we have every hope that as the Webb telescope gets ready to launch, people understand this really is that next generation. It's a real exciting time and a significant program for NASA."
Visiting the Webb?
The students also got to meet a real-life astronaut, former NASA spaceflyer John Grunsfeld, who visited the Hubble Space Telescope during three separate space shuttle missions. Grunsfeld now heads the Space Telescope Science Institute in Baltimore, Md.
A big difference between Hubble and its successor, he said, is that James Webb is designed to travel much farther out in space, to a point about a million miles away from Earth, which is about four times farther than the moon.
At that distance, it won't be feasible for astronauts to hop into a spacecraft and visit if the telescope needs an upgrade.
"With the Hubble, I always felt like if something goes wrong, it's OK, we'll just go fix it," Grunsfeld said in an interview. "With the Webb Space Telescope, if something goes wrong, that's really bad. What that means is that the engineers and designers have to be that much more careful."
Still, NASA is researching novel means of space propulsion for future manned missions, so it's not completely out of the question that astronauts could one day travel to the Webb, though that's not the current plan.
"We have, in NASA's history, done the amazing," Garver said. "We never say never at NASA."
The telescope is a cooperative effort among 15 nations, with primary contributions from NASA, the European Space Agency and the Canadian Space Agency. Europe will aim to launch James Webb in mid-2014 on an Ariane 5 rocket from Kourou, French Guiana.
"It's a wonderful feeling now we're in sight of launch," said John Mather, James Webb Space Telescope senior project scientist. "We're actually building the parts."