Webb telescope completes first course correction burn, deploys important antenna – Spaceflight Now


A view of the round high-gain antenna in its stowed place on the James Webb Area Telescope. Credit score: Stephen Clark / Spaceflight Now

The James Webb Area Telescope fired its rocket thrusters for the primary time late Saturday to line up for course towards an observing submit almost one million miles from Earth, then deployed a high-rate communications antenna Sunday to transmit science information to the bottom.

The milestones have been the primary main occasions for Webb since its profitable launch Christmas morning aboard a European Ariane 5 rocket from French Guiana. The Ariane 5 positioned the 13,584-pound (6,161-kilogram) observatory proper heading in the right direction on a course into deep area, with Webb in stretched, or elliptical, orbit with an apogee, or excessive level, greater than one million kilometers (600,000 miles) from Earth.

After deploying its photo voltaic array and priming its propulsion system following separation from the Ariane 5 higher stage, the spacecraft fired one in all its important thrusters starting at 7:50 p.m. EST Saturday (0050 GMT Sunday) for the mission’s Mid Course Correction 1a, or MCC 1a, maneuver.

The Ariane 5 rocket aimed to deploy the almost $10 billion observatory at a velocity simply shy of the pace required to succeed in the L2 Lagrange level, a gravitationally-neutral spot almost one million miles (1.5 million kilometers) from Earth, 4 occasions farther than the moon’s orbit.

The launch trajectory was chosen to make sure Webb might make up the pace required to enter orbit across the L2 Lagrange level, reasonably than needing to show round to make use of its thrusters for a braking maneuver. A burn to decelerate would power Webb to level its delicate optics towards the solar, risking harm.

The Ariane 5 rocket positioned Webb nearly precisely on its deliberate course into deep area, in keeping with officers from NASA and the European Area Company, which provided the launch car as a part of its contribution to the mission.

Webb fired one in all its 4 hydrazine-fueled Secondary Combustion Augmented Thrusters, or SCATs, for 65 minutes Saturday evening, making up almost all the anticipated velocity shortfall wanted to succeed in an orbit across the L2 Lagrange level.

One other burn, named MCC 1b, is penciled within the Webb flight plan Monday evening. Keith Parrish, Webb’s commissioning supervisor at NASA, stated earlier than the launch that the MCC 1b burn won’t be required, relying on the trajectory evaluation following the MCC 1a maneuver.

Webb controllers on the Area Telescope Science Institute in Baltimore, Maryland, carry out ranging measurements with the spacecraft utilizing radio indicators handed between Webb and floor stations all over the world. The info provides engineers details about Webb’s location and pace, permitting navigators to plot future trajectory correction maneuvers. In some instances, they may not be wanted, Parrish stated.

One other mid-course correction burn, designated MCC 2, is deliberate 29 days after launch — round Jan. 23 — to inject Webb into its halo orbit round L2.

Webb has 4 important SCAT engines. One redundant pair is used for the MCC 1a and 1b burns, whereas the opposite redundant set is used the MCC 2 maneuver and all subsequent stationkeeping burns to maintain Webb in its orbit round L2 throughout its science mission.

Sixteen smaller thrusters, divided into eight thruster modules every with two engines, are used for pointing management and to dump momentum from the observatory’s six spinning response wheels, which steer Webb towards its science targets. The response wheels have been activated quickly after Webb’s launch Saturday.

Artist’s illustration of the James Webb Area Telescope firing its engines. Credit score: NASA/Goddard

With the MCC 1a burn out of the best way, Webb deployed its high-rate communications antenna shortly after 10 a.m. EST (1500 GMT) Sunday, in keeping with NASA.

The Gimbaled Antenna Meeting, or GAA, consists of Webb’s 2-foot-diameter (60-centimeter) high-gain dish antenna. The Ka-band antenna will likely be used to transmit a minimum of 28.6 Gbytes of science information down from the observatory, twice per day, NASA stated.

Floor groups launched and examined the movement of the antenna throughout Sunday’s deployment exercise.

Earlier than the discharge of the Ka-band antenna, Webb communicated to floor groups utilizing a broad-beam S-band antenna at decrease information charges. The Ka-band high-gain antenna can downlink information at a pace of as much as 3.5 Mbytes per second.

Different steps accomplished on Webb’s first full day in area included the switch-on of temperature sensors and pressure gauges on the telescope, used for monitoring Webb’s thermal and structural parameters, NASA stated.

The antenna launch and first mid-course correction burn set the stage for the following step of Webb’s post-launch commissioning — the deployment and tensioning of the observatory’s tennis court-sized sunshield.

The five-layer thermal barrier will preserve Webb’s telescope and devices in everlasting shade, permitting the optics and detectors to succeed in a temperature of minus 388 levels Fahrenheit, or 40 levels above absolute zero. The super-cold temperatures are obligatory for Webb’s infrared devices to detect faint infrared gentle from the distant universe.

Two pallets containing the sunshield membranes will fold down from their launch place as quickly as Tuesday, if controllers keep on the pre-planned flight schedule. That may permit for the discharge and tensioning of the sunshield this weekend.

Two wings holding six of Webb’s 18 hexagonal major mirror segments are anticipated to fold into place in early January, constructing the form of the observatory’s 21.3-foot-diameter (6.5-meter) optical floor. Then comes extra steps to align the mirror and convey it into focus, all whereas engineers activate and check every fo Webb’s 4 science devices.

However Webb’s time-sensitive commissioning steps — the photo voltaic array deployment and first course correction burn — at the moment are full. Groups have extra flexibility in scheduling the remaining commissioning steps over the following six months, culminating within the launch of the primary science photographs a while in mid-2022.

E mail the creator.

Comply with Stephen Clark on Twitter: @StephenClark1.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button