How NASA&amp;#8217;s James Webb Space Telescope Could Spot Earth-like Planets

The James Webb Space Telescope has been in the news a lot lately. Often referred to as the replacement for the Hubble Space Telescope, its existence has been in jeopardy since a House committee voted to cut its funding this summer. While the telescope promises to revolutionize space science, its expanding budget has caused politicians and others to wonder if the promised returns justify the cost.

The JWST is not merely an upgraded version of Hubble. Rather than measure visible or ultraviolet light like Hubble does, JWST will detect infrared wavelengths from 0.6 (orange light) to 28 micrometers (deep infrared radiation of about 100&amp;#160;K, about minus 173 degrees Celsius or minus 280 degrees Fahrenheit).

Because JWST will be looking for heat, the telescope has to be kept very cold, and shielded from radiation coming from the sun, Earth and moon. To keep the telescope&amp;#8217;s temperature down to 40 degrees Kelvin (minus 233&amp;#160;C or minus 388&amp;#160;F), JWST will have a large sunshield and will orbit the sun at Lagrange Point 2.

The orbit of JWST will be 930,000 miles (1,500,000 kilometers) from the Earth, nearly 4 times farther than the distance between the Earth and the moon. The balance of gravitational forces from the Earth and sun at the L2 point will keep JWST in a stable orbit without having to expend much energy. However, this great distance also means servicing or repairing the telescope after launch may not be possible.