Webb is scheduled to launch in 2021.
No. The Webb and Hubble missions are expected to overlap, providing complementary science. Hubble will continue its mission as long as its instruments are functioning.
No. Unlike Hubble, Webb is not designed to be serviced. Webb will be located at a much greater distance than Hubble, beyond the Moon, instead of orbiting just above Earth. This is the reason that the minimum science mission length is five years with a 10-year goal. To insure the five-year mission, NASA has engineered Webb so that all critical subsystems are dual or will degrade gracefully with age. For instance, the Near Infrared Camera has two identical camera systems so that the optical quality can be maintained even if one fails.
Webb will also contain enough fuel for 10 years of maneuvers at its location. As with Hubble, NASA’s Chandra X-ray Observatory, and NASA’s Spitzer Space Telescope, the Webb Science and Operations Center at the Space Telescope Science Institute has the ability to change the operations of the observatory to maximize its scientific potential as it ages.
Webb will travel for about a month to reach its orbit at the second Sun-Earth Lagrange point (L2), 1.5 million kilometers (940,000 miles) from Earth.
Webb will launch from the Guiana Space Centre (Le Centre Spatial Guyanais, CSG) in Kourou, French Guiana, onboard an Ariane 5 rocket provided by the European Space Agency.
Webb needs to be kept very cool to measure the heat from objects in the universe. LEO, where Hubble resides, is too close to heat coming off the Earth and Moon, which would interfere with Webb’s precise measurements.
Webb’s deployment in space involves unfolding the sunshield and mirrors, a process that must be carefully conducted over nearly a month. The sequence is best explained visually in our deployment animation.
Webb will undergo science and calibration testing once it reaches its orbit, so regular science operations and the best images will begin to arrive around six months after launch. However, it is normal to also take a series of "first light" images that may arrive slightly earlier.
The Webb telescope is named after James E. Webb (1906–1992), NASA's second administrator. James Webb is best known for leading Apollo, a series of lunar exploration programs that landed the first humans on the Moon. However, he also initiated a vigorous space science program that was responsible for more than 75 launches during his tenure, including America's first interplanetary explorer spacecrafts. Read more about the life and impact of James Webb.
Webb’s segmented primary mirror has a diameter of 6.5 meters (21.6 feet). Each of the 18 segments is 1.4 meters (4.5 feet) in diameter. The area of the mirror is 25 square meters (269 square feet) and the mass is 705 kilograms (1,554 pounds).
The sunshield dimensions are 21.2 by 14.2 meters (69.5 by 46.5 feet) and the height of the entire observatory is 8 meters (28 feet).
To accurately and precisely detect faint infrared light from distant objects in the universe, Webb must be shielded from the strong infrared light emanating nearby from the Sun, Earth, and Moon. The sunshield’s five layers block the light from these nearby objects.
Webb is designed to have a minimum five years of science operations, with the goal of having an overall mission lifetime greater than 10 years.
Webb has four scientific instruments, the Near-Infrared Camera (NIRCam), the Near-Infrared Spectrograph (NIRSpec), the Near-Infrared Imager and Slitless Spectrograph (NIRISS), and the Mid-Infrared Instrument (MIRI). Each of these instruments uses infrared detectors to capture light from distant astronomical sources.
The Webb telescope is powered by an on-board solar array. It also has a propulsion system to maintain the observatory’s orbit and attitude. The solar array provides 2,000 watts of electrical power for the life of the mission, and there is enough propellant onboard for at least 10 years of science operations.
Webb can downlink at least 57.2 gigabytes of recorded science data each day, with a maximum data rate of 28 megabits per second.
The sunshield layers are built with ripstops included, so if something pierced a layer, it couldn't rip very far, allowing the layer to maintain structural integrity.
The primary mirror segments and secondary mirror are moved by six actuators that are attached to the backs of the mirrors. The primary segments have an additional actuator at the center of the mirror to adjust their curvature. Those seven spots are adjustable to align the 18 segments of the primary mirror to each other, and adjust the primary and secondary mirrors to the fixed tertiary mirror and the instruments.
Over the course of six months, as Webb orbits the Sun with the Earth, it has the ability to observe any point in the sky. Webb’s field of regard is limited to a 50-degree swath of the celestial sphere.
Webb will be able to measure light wavelengths from 0.6 to 28.5 micrometers. The capabilities of the individual instruments are:
- Near-Infrared Camera (NIRCam): 0.6–5 micrometers
- Near-Infrared Spectrograph (NIRSpec): 0.7–5 micrometers
- Mid-Infrared Instrument (MIRI): 5–28.5 micrometers
- Near-Infrared Imager and Slitless Spectrograph (FGS/NIRISS): 0.6–5 micrometers
Infrared radiation cannot be seen with the human eye, though it is emitted by all matter other than dark matter. Using infrared astronomy, we can see details in the universe and determine the composition of distant objects, from exoplanets to galaxies.
As a NASA mission, all data from Webb will be publicly available online.
Webb will study both the far and near universe. Astronomers will use it to see infrared light emanating from planets and objects in our solar system, exoplanets, star clusters, nebulae, other galaxies, and the most distant reaches in the universe.
Webb has a limiting sensitivity of ~11 nJy, which means we can see objects of 25th magnitude at near-infrared wavelengths and 22nd to 23rd magnitude objects at mid-infrared wavelengths. This means that Webb can see things that are over 2.5 million times fainter than the faintest thing you can see with your eye.
Webb will be able to observe galaxies that formed about 400 million years after the big bang.
Webb will be able to observe certain hot, young exoplanets using a technique called direct imaging.
Equipped with sensitive spectrographs, Webb will be able to detect oxygen and other organic molecules in the atmospheres of nearby exoplanets. These organic molecules will reveal clues to the potential habitability of other worlds.