James Webb Space Telescope: 5 cool things to know
On Thursday, November 17, 2011, the House and Congress came to an agreement for the fiscal year 2012 budget that includes funding for NASA and approves the full requested funding for the James Webb Space Telescope, the successor to the magnificent Hubble Space Telescope. The Webb, which came under fire in July 2011 when the House proposed cutting its funding entirely, will receive $529.6 million, the amount required for it to stay on track for its planned 2018 launch.
Here are five cool things – which you might not know – about the Webb.
The James Webb Space Telescope will unfold in space
The huge telescope will be launched on an Ariane 5 rocket, provided by the European Space Agency (ESA). But because of its massive size — it’s as big as a tennis court and about 40 feet (12 meters) high — it has to be folded up for the trip into space. Many features of the telescope, such as the hexagonal shape of the mirrors, were designed to let the telescope unfold while in space. Check out the video above for a glimpse of how Webb’s unfolding will take place.
It promises to be a nail-biter!
The Webb will be nearly 1 million miles from Earth
To be exact, it’ll be 940,000 miles (about 1.5 million kilometers) from Earth.
It’s being sent to what’s known as the L2 – the 2nd Lagrangian point in the Earth/sun system. The Lagrangian points are named for Joseph Louis Lagrange, who realized that there would be stable or semi-stable points in the vicinity of every two orbiting bodies in space.
In other words, every time you have two orbiting bodies, you also get five Lagrangian points. At these points, a third body can maintain a relatively stable orbit without the heavy usage of thrusters and propellants.
In this case, the sun and Earth are the two bodies in space. The Webb Telescope will orbit the L2 point in the Earth/sun system, which means it will follow Earth around the sun, always in a straight line with the Earth and sun. Its orbit will be far from Earth – beyond the moon’s orbit.
For comparison, the Hubble Space Telescope is only 380 miles (about 600 km) away in low-Earth orbit.
Its 18 mirrors are coated in gold
Webb’s purpose is to read infrared light, the wavelength of light that is emitted by the farthest objects in the universe. So the telescope’s mirrors will be coated with a thin layer of 24-karat gold. Gold reflects red light better than other materials, making the mirror 98 percent reflective, rather than the 85 percent achieved by ordinary mirrors.
Its science instruments will operate at temperatures near absolute zero
Absolute zero is the theoretical temperature at which all molecular and atomic motion ceases.
Everything that exists emits infrared radiation, which is produced from the vibration of atoms. The colder something is, the less infrared it emits. Because Webb is designed to work in the infrared, but emits infrared itself, it must be kept as cold as possible to keep its interference with itself at a minimum. Webb’s massive sunshield divides the telescope into a hot side, with temperatures around 185 degrees F, and a cold side, around -388 degrees F, or 40 Kelvin. In contrast, the coldest temperature ever recorded on Earth was -129 degrees F.
Planning for the Webb telescope began in 1995
Just five years after Hubble launched, scientists at the Space Telescope Science Institute (STScI) in Baltimore, Maryland, first envisioned what its successor would look like. At that point, they knew it would take many years to bring this vision to fruition.
Now the Webb is scheduled to be launched in 2018, and it’s a safe bet that astronomers soon will begin imagining an instrument to extend our vision with a telescope even grander and more powerful than the Webb.
Bottom line: The James Webb Space Telescope is the next-generation space telescope, following Hubble. It’s scheduled to launch in 2018. Here are 5 cool things to know.