James Webb Space Telescope will orbit earth 1.5 million kilometres away; here's why

The James Webb Space Telescope is ready to go to extreme lengths in unravelling many cosmic mysteries after it launches on December 25. A successor of the Hubble Space Telescope, Webb has an edge over the former due to a number of factors such as size, strength and most importantly, its orbit. Creators of the telescope - NASA, ESA and the Canadian Space Agency (CSA), have planned Webb's orbit 1.5 million kilometres from Earth, the reason behind which is totally practical. 

Perks of staying distant

Unlike the Hubble Space Telescope, which is 570 kilometres from Earth, the Webb telescope, will be sent far into a region which is called the second Langrage point or L2. In a report, NASA's Goddard Space Flight Center explained that Langrage points are gravitationally stable and the speciality of this orbit is that it allows the telescope to be in alignment with the Earth as it moves around the Sun. Besides, the location will also keep Webb cool during its lifespan, as it will study light in infrared wavelength, which can sometimes be felt as heat. To endure the heat, scientists have fitted Webb with five sun shields which are as big as a tennis court when unfurled. Such massive distance would also help the telescope shielded from the heat emerging from the Sun, the Earth and the Moon.

The telescope has another interesting angle to its deployment to the Langrage point. Since Webb has been designed to be extremely sensitive to infrared light, it also needs to be kept away from any bright and hot sources, a job that will be done by the heat shields. In fact, the heat shields will not only separate Webb's sensitive mirrors and scientific instruments from the energy sources but also prevent the heat on one side of the telescope reach another side. According to NASA, Webb's scientific instruments on the opposite side of the sun will operate at about 225 degrees below zero Celsius while the other side would endure temperatures up to 85 degrees celsius. 

Image: NASA

According to NASA, Webb would take six months to complete one orbit however the path of the telescope will keep it out of the shadows of both the Earth and Moon, allowing unimpeded science operations. 

Image: Twitter/@NASAWebb