The James Webb Space Telescope is about to enter orbit around the L2 point

Since its launch on December 25, 2021, the James Webb Space Telescope has come a long way. In the next few hours, there will be a new step forward with its orbit around point L2 (Lagrange). This fundamental step to allow the large telescope to be able to observe the sky while ensuring several advantages. Meanwhile, the primary and secondary mirrors have been put in place “neutral” and are ready for final alignment.


Thanks to an update of the official site, it was possible to follow the movements of the different segments of the large primary mirror. It is 18 hex segments made of beryllium and covered with a very thin layer of gold and glass which allows a good part of the reflection to be reflected infrared radiation. This will allow scientists to detect fainter objects. For the final alignment, it will take about five months since each segment must move individually. As written in the past, the adventure of JWST extension only at the beginning.

Orbit around the second Lagrange point (with defined orbit “Halo” or “with halo”), as expected, gives a series of advantages to the JWST extension. To do this, the engineers will fire up the motors again for the corrective maneuver called MCC2 (mid-course correction burn). It is the last planned before arriving in its final orbit. Previously there had been MCC1a and MCC1b which had been used to recover part of the speed during the departure from Earth. The MCC2 maneuver will take place at 8:00 p.m. (in Italy) on January 24.

The James Webb Space Telescope and the second Lagrange point (L2)

The engineers following the mission also briefly explained the choice to place the James Webb Space Telescope right in that part of space. First of all, at this point in Space, the gravitational forces of the Sun and the Earth are in balance. You chose not to be “precisely” at point L2 but in orbit around it because it is an easier position to reach and more efficient from the point of view of the use of propellant. The amount of propellant is one of the major limitations of the mission.

James Webb

No possibility of restocking is currently planned. However, the space agency does not rule out that solutions that are currently too expensive or complex may not be found in 20 years. However, it should be remembered that part of the cost of the mission also resides in the ground personnel employed to manage it. These are currently already calculated for the first 5 years (and possibly for 10 years). It will therefore be necessary that the Nasa convince partners (ESA and CSA) and American politicians of the usefulness of the scientific instrument.

The JWST extension it can be positioned so that the Sun, Earth and Moon are always hidden from the great sunscreen so that the instruments are not affected by the infrared radiation emitted by these bodies. Also, in orbit around the L2 point, the Earth and the Moon will never eclipse the Sun, which will allow me solar panels always power the telescope itself.

webb telescope

Always facing one side of the sky, the James Webb Space Telescope he will be able to observe almost half of the celestial vault at any time, while in six months he will be able to observe it completely (since in addition to rotating around point L2 he will follow the Earth in its orbit). Communications to the operations center will also be simplified with the possibility of communicating every day for four hours a day thanks to the Deep Space Network and to the Spanish, Australian and American branches.

Currently the James Webb Space Telescope it is 1.42 million km from Earth and has completed about 97% of its journey to point L2. Its current speed is 0.2139 km/s while the recorded temperatures are 57C and 11C (hot side) and -207C and -201C (cold side). As written above, the first image after the alignment of the mirror should arrive in about five months, the subject being the Large Magellanic Cloud.

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