Even for a state-of-the-art spacecraft like the James Webb Space Telescope. His journey from Earth to a parallel orbit outside our planet required extremely precise calculations, decades of planning and almost perfect execution, at every step. But even now, with NASA’s flagship Lagrange 2 point (L2) space telescope in motion, Webb has more work to do than astronomy alone – with maneuvering propellers needed to counteract the Sun’s constant thrust. on the spacecraft to maintain relative proximity to Earth, according to a NASA blog post. This is the story of Webb’s journey from Europe’s Arianespace launcher ELA-3 near Kourou, to French Guiana at L2, and the challenges that lie ahead.
The millions of miles of the James Webb Telescope
Webb’s initial launch on December 25, 2021, gave him most of the kinetic energy needed to carry it on its journey of millions of miles to L2. This speed is provided by the colossal Ariane 5 rocket. But there was still a lot of work to be done. After the launch, Webb was released from his launcher and was ready to use his own on-board propellants. “Webb will use his own small rocket propulsion system to adjust its approach to its final halo orbit around point L2,” said a NASA blog that was released several weeks before the launch. Webb will use his own system of small rocket launchers to adjust his approach to his final halo orbit around point L2 (pictured below), where the telescope and instruments will cool in the shadow of the huge sun protection, protected by the heat. of the Sun, the Earth and the Moon “. Get more updates on this story and more with The Blueprint, our daily newsletter: Sign up for free here. However, additional maneuvers were needed on the way to Webb’s final orbit, a total of three: “a third a month later, to make it easier for Webb to orbit L2,” according to a NASA blog post. A regular view of Webb’s journey from Earth to L2 orbit. Source: Steve Sabia / NASA Goddard
A Havard astronomer wonders when Webb will maneuver to maintain stations
And now positioned in orbit around L2, these launchers will continue to fire periodically to “maintain that trajectory, with small maneuvers called ‘station maintenance,’” according to a NASA post. These station maintenance maneuvers were originally to be done once every 21 days. These maneuvers are necessary because the pressure of the solar radiation accumulates on the large sun protection surface of the James Webb Space Telescope. “Although the Webb is designed to keep this pressure well balanced, the angular momentum increases as the telescope moves in different directions, so occasionally small discharge maneuvers are required to keep the observation wheel’s reaction wheels within proper range. “, Says NASA. Position. Reaction wheels are flywheels designed to help Webb maintain its payload in the right direction. But, paradoxically, updates about the station holding the maneuver with a propeller were not immediately forthcoming. Harvard Astrophysics Center astronomer Jonathan McDowell noted this small hiccup in the information with a tweet: “I wonder if we’ve heard anything about L2 station burns – shouldn’t there have been at least one by now?” Hi @marshallperrin, the progress at JWST PSF is extremely exciting! But I wonder if we have not heard anything about the L2 station burns – should not there have been at least one by now? – Jonathan McDowell (@ planet4589) March 22, 2022
Webb will perform station maneuvers every 42 days
As an expert and author in space, McDowell’s question came at an interesting time. Webb had been in L2 orbit since late January, but there appeared to be no information on the station’s maintenance maneuvers. In theory, this could be a big problem – if propellers were not fired to correct the Sun’s huge thrust, the James Webb Space Telescope could be pushed from its ideal orbit around L2 and orbit a planetary body in the solar system. our system. or completely out of the system. But a NASA document reveals that Webb’s idea of maneuvering guard stations every 21 days was scrapped because the lack of a station maneuvering window meant he would not have another window for a very long time – big enough for James. The Webb space telescope will move away from its position and lose its primary target (LPO). “If we missed a maneuver and then for some reason could not perform the next maneuver 21 days later, we could end up waiting 63 days between [station keeping] maneuvers, which pose a potential risk to an LPO mission, “the NASA document states. Webb’s station maintenance maneuvers are crucial to its mission. Source: NASA In other words, a short period between station maintenance maneuvers can ironically put Webb in jeopardy. In most cases a [station keeping] The maneuver will take place every 42 days, not every 21 days, “said the NASA document. not yet happen until sometime in April. The end of the beginning – The James Webb Space Telescope is a marvel of engineering – incorporates four dynamic primitive instruments that will not only look at the very early universe, revealing the origin of stars and galaxies, but also working in parallel to reveal statistical characteristics of the entire universe, giving a new and colossal set of data from which we can finally try to solve the greatest mysteries in physical science. And, of course, he can find signs of extraterrestrial life.
