NASA James Webb Space Telescope, all steps between now and six months
NASA James Webb Space Telescope
NASA's $ 10 billion James Webb Space Telescope was launched atop an Ariane 5 rocket from French Guiana on December 25, kicking off a long-delayed and potentially transformative mission to study the early universe, nearby exoplanets and more. The science team members will have to remain patient, however, as the telescope has a lot of work to do before it becomes operational.The telescope is directed towards the Sun-Earth Lagrange Point 2 (L2), a gravitationally point stable 1.5 million kilometers from our planet in the direction of Mars. It will take 29 days for Webb to get there, and there will be a lot of work to do in the meantime. "The Webb Observatory has 50 major implementations ... and 178 release mechanisms to deploy those 50 parts," said Mike Menzel, Webb mission systems engineer, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a video. explanatory note called “29 Days on the Edge” that the agency released in October. "Each of them has to work," Menzel said. "Deploying Webb is arguably the most complicated space activity we have ever done."
Webb has already reached some important milestones. About half an hour after takeoff, for example, it deployed its solar panels and began absorbing energy from the Sun, while a few nights ago the large telescope performed a crucial 65-minute engine start that set it on course for L2.
The day after launch, Webb also rotated its high-gain antenna towards Earth to further facilitate communications with its handlers, while yesterday it performed another engine start to refine its trajectory towards L2. Three days after launch, the pallet containing Webb's massive sun shield - a five-layer structure designed to keep the infrared telescope and its instruments cool - will be lowered.
Each of the shield's five sheets it is about the size of a tennis court when fully extended, too wide to fit the payload fairing of any currently operating rocket. So the sun shield was launched in a compact configuration and needs to be explained.
This is an incredibly complex process. The solar shield structure has 140 release mechanisms, 70 hinge assemblies, 400 pulleys, 90 cables and eight distribution motors, all of which must function properly for the five layers to distribute as intended, NASA officials said in the video. br>
The protective cover will detach from the sun shield five days after launch and its arms will extend one day later. Sunshield's deployment is expected to be completed within eight days of take-off, at which point team members will begin to shift their focus to optics.
Approximately 10 days after launch, Webb will extend its large secondary mirror 0.74 meters, which is so named because it is the second surface that photons from deep space will hit on their way to the telescope instruments.
It will then be time to open Webb's 6-wide primary mirror, 5 m. Consisting of 18 hexagonal segments, it was launched bent upwards, like the sun shield. Twelve to 13 days after launch, the mirror's two side “wings” will extend and lock into place, giving the surface its full size.
At that point, Webb will be in its final configuration. The huge observatory will arrive at its destination just over two weeks later, carrying out another engine start 29 days after launch to glide into orbit around L2, where a different set of ramp-up procedures will begin.
Two to three months after launch, the team will align the primary mirror segments so that they act as a single light-gathering surface. This will be painstaking and time-consuming work, because the mirror must be perfect with an accuracy of 150 nanometers. Meanwhile, the team will also test and calibrate Webb's four scientific instruments. This too will be a laborious process; the goal is to start regular scientific operations six months after launch.
James Webb Space Telescope sails beyond the orbit of the moon after 2nd course correction
NASA's next-generation space observatory has sailed beyond the orbit of the moon after nailing the second of three required course-correction burns, agency officials said Monday.
The long-awaited James Webb Space Telescope launched on Saturday (Dec. 25), beginning a one-month deployment process. Over the course of that deployment, the observatory must execute three burns to adjust its trajectory, the first of which began 12.5 hours after launch and lasted 65 minutes; the second, much shorter burn, is now also complete.
'At 7:20 pm EST — 60 hours after liftoff — Webb's second mid-course correction burn began,' NASA officials wrote in a statement released on Monday (Dec. 27). 'It lasted 9 minutes and 27 seconds and is now complete.'
Live updates: NASA's James Webb Space Telescope missionIn photos: The Christmas launch of NASA's James Webb Space Telescope
The spacecraft has also crossed the moon's orbit of Earth, according to a mission tweet. As of Tuesday, Webb was more than 293,000 miles (471,000 kilometers) from Earth. The average distance from Earth to the moon is about 280,000 miles (384,000 km).
'It's been a busy evening! Not only did we just complete our second burn, but #NASAWebb also passed the altitude of the Moon as it keeps cruising on to the second Lagrange point to #UnfoldTheUniverse,' Webb mission officials wrote. 'Bye, @NASAMoon!'
('Bye, moon,' is not literal here; the moon was elsewhere in its orbit and there was no close flyby. In fact, according to astronomer Jonathan McDowell, the observatory was closest to the moon while on the launch pad, since the spacecraft launched in the opposite direction.)
The spacecraft will execute its third and final course-correction burn about 29 days after launch, according to a NASA deployment timeline. This burn will be the mission's orbital insertion burn, establishing the spacecraft in a halo orbit around a point in space known as L2, or Earth-sun Lagrange point 2.
This location is nearly 1 million miles (1.5 million kilometers) away from Earth on the side opposite the sun. The remote location will help Webb detect infrared light precisely with minimal interference from the sun.
For now, however, the focus turns to the observatory's massive sunshield, which was carefully folded up for launch. Now, the spacecraft must unfold the shield, which stretches as long as a tennis court, and separate its five ultrathin layers. The sunshield, like Webb's location, is integral to the mission's goal of observing infrared light.
Sunshield deployment is tentatively scheduled to begin on Tuesday (Dec. 28), three days after launch, although each stage of deployment is controlled by personnel on the ground and the timeline is flexible.
First, Webb must deploy the sunshield's pallet and tower, then release a flap and the sunshield covers. That sequence of events is estimated to take about two days. Then, the sunshield's booms will deploy, unveiling the sunshield at its full width. By eight days after launch, the mission team hopes that the sunshield will be fully deployed.
Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.
