On January 25, NASA's James Webb Space Telescope (JWST) flew more than 1.6 million kilometers in space in the past month. It carried out the last heading correction operation on Monday local time and finally reached its final destination. Now, JWST will stay there forever and begin its mission to observe the oldest stars and galaxies in the universe < p > as the most powerful telescope ever launched into space, JWST was launched on Christmas day in 2021, but it was too large to enter space in its final form, so researchers had to fold it into a rocket for launch. After reaching space, JWST began extremely complex deformation and deployment actions. No spacecraft has ever demonstrated such super ability before. However, each deployment operation of JWST was performed seamlessly, and the main deployment was finally completed on January 8 and expanded into the final form < p > however, this process makes the task team full of concerns, because each step must be implemented as planned, and a small failure may endanger the whole task of JWST. However, the concerns of the mission team did not end after the launch, and JWST still had to enter the final orbit of space to complete the mission properly. If it does not decelerate properly, it may enter the wrong track or miss the target track completely. Such a failure could complicate the future of the mission and make it extremely difficult for scientists to communicate with the nearly $10 billion space telescope < p > fortunately, JWST completed the final deployment perfectly. "In the past month, JWST has achieved amazing success, which is a tribute to all those who have spent decades to ensure the success of the mission," bill Ochs, JWST project manager of NASA's Goddard Space Flight Center, said in a statement < p > although it took a month to reach this step, JWST did not take a long time to guide itself to the final destination. At around 2 p.m. EST on Monday, JWST started its airborne thrusters for about five minutes. This is the last time that JWST has completed three course corrections to slow down the spacecraft in order to enter its predetermined space orbit in a very accurate way < p > JWST now revolves around an invisible point in space, which is called the earth sun Lagrange point. This is a somewhat mysterious space area where the gravitational and centripetal forces of the sun and the earth reach a balance, so that objects can remain in a relatively stable position. "Where gravity is perfectly balanced, there is a small tug of war going on, but no one has won yet," said Jean Paul Pinaud, an executive at Northrop Grumman, JWST's main contractor < p > the sun and the earth share five such Lagrangian points, which are scattered around the earth. JWST runs around a Lagrangian point called L2, which is farther from the sun. In this position, when the earth orbits the star, JWST will follow the planet almost synchronously, just like a constant companion, always in the same position relative to the earth. No matter where the earth revolves around the sun, JWST is guaranteed to be about 1.6 million kilometers away from us < p > the orbit of JWST around L2 is actually quite wide, roughly equivalent to the distance between the earth and the moon. But without the help of external forces, JWST cannot stay on this track forever. L2 is the so-called "pseudo stable orbit", that is, the object moving around this position tends to drift in one direction < p > therefore, JWST will have to make small adjustments to its operation orbit throughout its life cycle. Every 20 days or so, the telescope will start the propeller for two to three minutes to ensure that it remains in the predetermined orbit. Ultimately, these adjustments will determine how long JWST can remain active in space. When the propellant is exhausted in the next 10 to 20 years, the mission of the telescope will end < p > this may seem like a rather complex location and requires a lot of extra effort to maintain the stability of JWST. But for various reasons, L2 is the most attractive place for JWST, and perhaps the biggest advantage lies in its distance from the earth and the sun. JWST can collect infrared light, which is heat related light. Because of this design choice, the telescope must always maintain a very low temperature < p > that's why JWST is equipped with a sunscreen that always faces the sun. It will reflect the heat of the sun and keep the telescope cold. However, if NASA is not careful, any nearby objects emitting heat and infrared light may disrupt JWST's observations. By placing the telescope 1.6 million kilometers away from the earth, NASA ensured that infrared light from the earth and moon would not interfere with or heat the telescope < p > from an energy point of view, L2 is also appropriate because one side of the JWST is always facing the sun. On the heating side, the telescope has a solar panel that constantly collects sunlight to power it. Other spacecraft do not have such luxury designs, such as the Hubble Space Telescope orbiting the earth. Whenever Hubble runs on the back of the earth, it loses the view of the sun and must store energy in a battery. This will never happen to JWST. Kyle hott, head of JWST mission systems engineering at Northrop Grumman, said: "we basically have unlimited mission operations, and we don't have to worry about any solar eclipses." < p > when orbiting the earth, the continuous conversion day and night will also bring many effects. For example, the extreme fluctuation of temperature will make the spacecraft collide and vibrate, resulting in the degradation of its instruments over time. JWST will operate at approximately the same temperature throughout its life cycle < p > in addition, it has the advantage of maintaining continuous communication. Since L2 is always in the same position relative to the earth, JWST will maintain a specific distance from the earth at any time. This means that we can always keep in touch with the telescope. "We can be pulled by the earth and the sun in L2, so that we can maintain good, convenient and continuous communication with the telescope, which also simplifies a lot of mission operations," Holt said < p > entering the final orbit temporarily ended JWST's dangerous space journey and paved the way for scientific observation. However, we still need to wait for JWST to make final preparations. Before the telescope is put into use, scientists and engineers will soon begin to accurately aim at the telescope ?
2023-03-22 10:04:49