If Webb is orbiting the Sun further out than Earth, shouldn't it take more than a year to orbit the Sun? Normally yes, but the balance of the combined gravitational pull of the Sun and the Earth at the L2 point means that Webb keeps up with the Earth as it goes around the Sun. This is why L1, L2, and 元 don't "collect" objects like L4 and L5 do. However, L1, L2, and 元 are metastable so objects around these points slowly drift away into their own orbits around the Sun unless they maintain their positions, for example by using small periodic rocket thrust. Some small asteroids are known to be orbiting the Sun-Earth L4 and L5 points. In fact, L4 and L5 are stable in that objects there will orbit L4 and L5 with no assistance. Some Technical Details: It is easy for an object (like a spacecraft) at one of these five points to stay in place relative to the other two bodies (e.g., the Sun and the Earth). The L1, L2, and 元 points are all in line with each other - and L4 and L5 are at the points of equilateral triangles. At Lagrange points, the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them. Joseph-Louis Lagrange was an 18th century mathematician who found the solution to what is called the “three-body problem.” That is, is there any stable configuration, in which three bodies could orbit each other, yet stay in the same position relative to each other? As it turns out, there are five solutions to this problem - and they are called the five Lagrange points, after their discoverer. This is why the telescope is out at the second Lagrange point. To have the sunshield be effective protection (it gives the telescope the equivalent of SPF one million sunscreen) against the light and heat of the Sun/Earth/Moon, these bodies all have to be located in the same direction. The temperature difference between the hot and cold sides of the telescope is huge - you could almost boil water on the hot side, and freeze nitrogen on the cold side! The telescope itself operates at about 225 degrees below zero Celsius (minus 370 Fahrenheit). EST today to learn more about what’s next for the James Webb Space Telescope.+ The temperature difference between the hot and cold sides of the telescope is huge - you could almost boil water on the hot side, and freeze nitrogen on the cold side! Watch a special episode of NASA Science Live at 3 p.m. Now that Webb’s primary mirror segments and secondary mirror have been deployed from their launch positions, engineers will begin the sophisticated three-month process of aligning the telescope’s optics to nearly nanometer precision. “We are now on the verge of aligning the mirrors, instrument activation and commissioning, and the start of wondrous and astonishing discoveries.” “During the past month, JWST has achieved amazing success and is a tribute to all the folks who spent many years and even decades to ensure mission success,” said Bill Ochs, Webb project manager at NASA’s Goddard Space Flight Center. Webb has used as little propellant as possible for course corrections while it travels out to the realm of L2, to leave as much remaining propellant as possible for Webb’s ordinary operations over its lifetime: station-keeping (small adjustments to keep Webb in its desired orbit) and momentum unloading (to counteract the effects of solar radiation pressure on the huge sunshield). Webb’s orbit will allow it a wide view of the cosmos at any given moment, as well as the opportunity for its telescope optics and scientific instruments to get cold enough to function and perform optimal science. And I can’t wait to see Webb’s first new views of the universe this summer!” Click on the trajectory diagram for a full-screen version. We’re one step closer to uncovering the mysteries of the universe. “Congratulations to the team for all of their hard work ensuring Webb’s safe arrival at L2 today. “Webb, welcome home!” said NASA Administrator Bill Nelson. The final mid-course burn added only about 3.6 miles per hour (1.6 meters per second) – a mere walking pace – to Webb’s speed, which was all that was needed to send it to its preferred “halo” orbit around the L2 point. This mid-course correction burn inserted Webb toward its final orbit around the second Sun-Earth Lagrange point, or L2, nearly 1 million miles away from the Earth. EST, Webb fired its onboard thrusters for nearly five minutes (297 seconds) to complete the final postlaunch course correction to Webb’s trajectory.
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