The instrument that will form the heart of NASA's James Webb Space Telescope
, or JWST, has been assembled and tested by aerospace company Lockheed Martin under a contract from the University of Arizona.
for Near Infrared Camera, the instrument has been shipped to NASA Goddard Space Flight Center
in Greenbelt, Md. for final testing and mounting into the telescope structure. As the space telescope's prime instrument, NIRCam will peer deeper into space and time than any other instrument before.
The instrument was designed and built at the Lockheed Martin Space Systems Advanced Technology Center
in Palo Alto, Calif. The UA and Lockheed Martin are responsible for the NIRCam instrument design in terms of the optical, mechanical, structural, thermal and electronic precision mechanisms and the control software.
NIRCam's focal plane, which is similar to a digital camera's imaging sensor, was developed by a group led by Marcia Rieke
, a Regents' Professor of Astronomy in the UA Steward Observatory
"This is a huge step," said Rieke. "We are excited because it means we have completed the assembly of the full camera, and for the first time, we have a fully functional instrument."
"As we view the universe with more powerful tools, not only do we confirm or overturn current concepts, but we always learn new and exciting things," said Rieke.
Peering into the Dawn of the Universe
The JWST is NASA's next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, the JWST will observe the most distant objects in the universe, produce images of the very first galaxies ever formed, provide insight to how solar systems evolve and help explore planets around distant stars. The Webb telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
With its 6.5-meter (21-foot) mirror, JWST will enable observation of the most distant galaxies. The NIRCam design is optimized for finding first light sources, peering through clouds of hydrogen and dust in space that obscure these objects.
"We hope to observe the first galaxies that formed after the Big Bang," Rieke said. "We don't know exactly when that happened, and answering that question is one of the JWST's main goals."
Once the telescope has reached its destination behind the far side of the moon a little less than 1 million miles from Earth, at a position called Lagrange Point Number 2, it will use its 21-foot-diameter mirror to look for the first light-emitting galaxies and star clusters that formed in the universe after the Big Bang, image young stars in the Milky Way, study the physical and chemical properties of planets orbiting other stars, and objects within our solar system.
The camera is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like planets around distant stars. The NIRCam coronagraphs work by blocking a brighter object's light, making it possible to view the dimmer object nearby – just like shielding the sun from your eyes with an upraised hand can allow you to focus on the view in front of you. With the coronagraphs, astronomers hope to determine the characteristics of planets orbiting nearby stars.
"We will also use NIRCam to study some of the objects in the outer solar system, because the instrument is quite good at observing what kind of ice is present on those Kuiper belt objects," Rieke explained. "As far as planets around other stars go, JWST will look at those, too. Not so much to discover them, but to find out what their atmospheres are like."
In addition to Lockheed Martin and the UA, the NIRCam team includes Teledyne Imaging Sensors
of Camarillo, Calif. and a team of science co-investigators.
Shake Test Simulates Rocket Launch
The NIRCam instrument consists of two identical optical imaging modules and contains focal plane assemblies, or FPA, assembled at the UA using detectors provided by Teledyne. The FPA hardware consists of 40 million pixels and is designed for operation in the cold of deep space at 35 degrees Kelvin or about -400 degrees Fahrenheit.
Once NIRCam has arrived at Goddard Space Flight Center, engineers will inspect the instrument and perform tests to confirm nothing was harmed in transport, Rieke explained. Once cleared, it will undergo shake tests to simulate the vibrations expected during the rocket launch to make sure none of the connections comes loose. More tests will check the electronic components before NIRCam will be assembled into the telescope.
"In 2014, the whole telescope will be cooled down to 35 Kelvin," Rieke said. "We'll run tests to simulate taking star images, and we'll check that everything works well together."
In addition to NIRCam, a mid-infrared-wavelength camera is also part of the telescope's instrumentation. Developed by a group led by George Rieke, also a Regents' Professor at the UA Steward Observatory, that instrument has already been delivered to Goddard Space Flight Center, which manages the JWST project.
Girl Scout Motto Goes to Space
When JWST blasts off in 2018, it will take another UA contribution into space: Engraved into the edge of NIRCam's mounting plate is the slogan, "Go Girl Scouts!" in celebration of a special outreach program spearheaded by the UA.
"When we wrote the proposal for NIRCam back in 2001, NASA required us to have an educational plan separate from the science," said Don McCarthy
, a Steward Observatory astronomer who has engaged thousands of children and teenagers through his Astronomy Camp
, Arizona's longest-running science camp. "We established an official partnership with the Girl Scouts of the USA to get them involved not just in the science of JWST but astronomy and STEM education in general."
McCarthy said unlike most space missions that commence their outreach after launch, the UA's program was started as soon as NASA approved the JWST project.
"We believed that if you're serious about reaching people and spreading education, you have to do it immediately," he said. "We have hosted biannual training sessions in Tucson, where we invite adult leaders from all Girl Scout councils, and train them not only in what NIRCam is about, but get them involved in STEM education, and develop field astronomy activities with their troops."
The decision paid off especially in light of the fact that NASA recently cut its education and outreach funds across the board.
Although this has left the JWST outreach program without funding unless a resolution goes forward in Congress, 225 Girl Scout leaders have gone through the program and are making an impact around the nation by establishing astronomy and STEM initiatives in their local troops. Graduate students at Steward Observatory create materials and concepts for the program and work closely with the participants.
"Many of the leaders that have attended our camp came without a strong background in science or math," McCarthy said, "and they're surprised by the experience because they used to think science is about memorizing stuff. But they tell us, 'You guys teach us how to think and explore,' and with that change in attitude they can do remarkable things with their troops back home."
On June 18, Lockheed Martin hosted Girl Scout leaders from around the country for a send-off celebration of NIRCam. A similar event will be held once the instrument arrives at Goddard Space Flight Center.
The Space Telescope Science Institute
in Baltimore, Md. is developing the ground system for the mission and will be responsible for observatory operations and science program management.