James Webb Space Telescope launches successfully after years of delay
Summary
‘Milestone achieved’: Biggest, most powerful space-based observatory ever built lifted off at 7:20 am ET from a launchpad in French GuianaThe James Webb Space Telescope launched successfully early Saturday, rising skyward aboard an Ariane 5 rocket that lifted off at 7:20 a.m. Eastern Standard Time from a pad in Kourou, French Guiana, and beginning a 29-day journey to its orbital perch some 1 million miles from Earth.
“Milestone achieved," the National Aeronautics and Space Administration said in a tweet after the launch, adding that the telescope was “safely in space, powered on and communicating with ground controllers."
For scientists world-wide, the sun-orbiting observatory—the largest, most powerful instrument of its type ever built—will herald a new era of discovery in space. One hundred times as powerful as the Hubble Space Telescope, Webb will help astronomers peer at some of the oldest galaxies and stars in the universe, search for signs of habitability in the atmospheres of planets outside our solar system and study mysterious forces like dark energy using its infrared sensors.
“What an emotional day," said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. The launch marks “the beginning of one of the most amazing missions that humanity has ever conceived," he said.
The launch was delayed twice in recent weeks, first because of technical issues and then because of poor weather.
To fit it into the rocket’s 18-foot-wide, 56-foot-high nose cone, mission scientists had to build the telescope’s gold-plated mirror—measuring 21.5 feet in diameter when fully deployed—as 18 separate segments that have to fold together like petals of an origami flower.
Shortly after launch, the telescope successfully separated from the rocket and deployed its solar array so that it can begin generating electricity and charging its batteries, NASA said. Within the next 24 hours, plans call for mission scientists to command Webb to course-correct using on-board rockets so that it heads toward a point four times as distant as the moon called the second Lagrange point.
Then, complicated unfolding processes will begin, taking about two weeks to complete. Seventy hinges, 90 cables, 140 releases and 400 pulleys will be involved in unfolding the telescope’s tennis court-size sunshield by issuing commands to Webb from Earth. Webb will then open the two wings of its primary mirror and lock them in place.
“Now we have to realize there are still innumerable things that have to work, and they have to work perfectly," NASA Administrator Bill Nelson said. “But we know that with great reward there is great risk."
Webb has 344 “single-point failure" items. A single-point failure is a piece of equipment or part of the system that, should it fail, could scuttle the entire mission.
About 80% of those items are associated with the sunshield deployment. If a deployment mechanism malfunctions, or the sunshield snags as it unfolds, there is no way to repair it from Earth.
But if a malfunction were to occur, that doesn’t necessarily mean Webb would become a $10 billion piece of space junk.
“There are enough redundancies built in that everything will be OK," said Michael Maseda, an assistant professor of astronomy at the University of Wisconsin-Madison. “If one thing doesn’t work it won’t completely cancel the mission."
A malfunction might affect Webb’s ability to see fainter stars or galaxies.
“Even with Webb at 90%, we’re still going to be seeing things we’ve never seen before," he said.
It will take Webb 29 days to reach the second Lagrange point. There it will orbit the sun, 1 million miles from Earth, until at least 2026.
If all goes well, Webb can start conducting its first science experiments about six months after launch and is expected to produce its first photo this summer. It takes that long to completely unfold and align its mirrors, calibrate its cameras and infrared light spectrographs, and cool the telescope to its operating temperature. The telescope was jointly developed by NASA, the European Space Agency and the Canadian Space Agency.
Webb’s mission is expected to last at least five years, though it will likely be 10, Dr. Maseda said. That timeline is constrained by the amount of fuel Webb has on board—fuel that is necessary to keep the telescope in its proper orbit and pointed in the direction that astronomers want it.
Webb is designed to complement Hubble, which is orbiting Earth after being launched in 1990 on what was planned to be a 15-year mission. A series of technical issues shut it down twice this year.
“Hubble’s really elderly," said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics.
If the Webb mission fails and Hubble stops working, “it would mean there’s a gap in our capabilities and we might be without a major space telescope for a while," he added.
Likely, the next space telescope to launch is the Nancy Grace Roman Space Telescope, which won’t be ready until the mid-2020s.
“History of these big projects has been that success gives success," said Robert Smith, a historian of astronomy at the University of Alberta in Canada. “If Webb is a spectacular success, and there’s no reason to think it won’t be if everything works, then it makes future flagship missions more likely."