The Webb Telescope performs one of its most critical maneuvers

The Webb Telescope performs one of its most critical maneuvers


A little more than twelve hours after the launch of Ariane 5, the thrusters of the James Webb Telescope successfully fired to correct its trajectory. This was one of the most critical manoeuvres of the weeks-long journey towards Point L2.

After several years of waiting, it’s finally done! This Saturday, December 25 at 13:20, French time, many engineers, astronomers and enthusiasts held their breath for several minutes as Ariane 5 launched from Guyana. In his headdress was the largest and most powerful space observatory in all of history. Its goal: to expand our knowledge about the Universe and why not lift the veil on some of the most persistent mysteries of astrophysics.

In the meantime, it is appropriate to arrive on the spot, around the Lagrange point 2, more than 1.5 million kilometers from the Earth. During this trip, the Webb Telescope will also have to perform several essential maneuvers.

Trajectory correction
One of them was successfully executed about 12.5 hours after launch. While it was about 160,000 km from Earth, the observatory in fact performed a burn of its thrusters to correct its trajectory, thus ensuring that it would reach its destination safely.

Trajectory correction is a fairly common operation in the hours after the launch of a spacecraft. In general, these maneuvers involve turning over in order to slow down. In the case of the Webb Telescope, this was impossible, since its ultra-sensitive instruments would have been exposed to the Sun.

Thus, the observatory could only increase its speed. In anticipation, the observatory’s launch sequence was designed to provide just a little less power than needed rather than just a little more. This burn, nicknamed Mid-Course Correction Burn 1a (or MCC1a), was therefore an opportunity for the observatory to refine its trajectory towards L2.

According to NASA, this was the largest of three planned burns during this trip and the only one that needed to be carefully timed.

The rest of the program
From the third day, this Tuesday, the Webb Telescope will begin to deploy its sun visor in order to prevent sunlight from reaching the infrared sensors of the telescope, the most essential parts of this mission. To probe the depths of the cosmos, the observatory must in fact operate at extremely low temperatures. This crucial maneuver is normally expected to take place in three days, involving about 7,000 pieces.

After six days of flight, the telescope’s secondary mirror will in turn have to deploy before the gold-lined main mirror opens the next day. Then again, everything will have to work properly at the risk of making the mission fail. Finally, a month after launch, the Webb Telescope should reach the L2 point.