Connect with us

News

Webb telescope completes first course correction burn, deploys main antenna

Published

on

 

A view of the circular high-gain antenna in its stowed position on the James Webb Space Telescope. Credit: Stephen Clark / Spaceflight Now

The James Webb Space Telescope fired its rocket thrusters for the first time late Saturday to line up for course toward an observing post nearly a million miles from Earth, then deployed a high-rate communications antenna Sunday to transmit science data to the ground.

The milestones were the first major events for Webb since its successful launch Christmas morning aboard a European Ariane 5 rocket from French Guiana. The Ariane 5 placed the 13,584-pound (6,161-kilogram) observatory right on target on a course into deep space, with Webb in stretched, or elliptical, orbit with an apogee, or high point, more than a million kilometers (600,000 miles) from Earth.

After deploying its solar array and priming its propulsion system following separation from the Ariane 5 upper stage, the spacecraft fired one of its main thrusters beginning 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 nearly $10 billion observatory at a velocity just shy of the speed required to reach the L2 Lagrange point, a gravitationally-neutral spot nearly a million miles (1.5 million kilometers) from Earth, four times farther than the moon’s orbit.

The launch trajectory was selected to ensure Webb could make up the speed required to enter orbit around the L2 Lagrange point, rather than needing to turn around to use its thrusters for a braking maneuver. A burn to slow down would force Webb to point its sensitive optics toward the sun, risking damage.

The Ariane 5 rocket placed Webb almost exactly on its planned course into deep space, according to officials from NASA and the European Space Agency, which supplied the launch vehicle as part of its contribution to the mission.

Webb fired one of its four hydrazine-fueled Secondary Combustion Augmented Thrusters, or SCATs, for 65 minutes Saturday night, making up nearly all of the expected velocity shortfall needed to reach an orbit around the L2 Lagrange point.

Another burn, named MCC 1b, is penciled in the Webb flight plan Monday night. Keith Parrish, Webb’s commissioning manager at NASA, said before the launch that the MCC 1b burn might not be required, depending on the trajectory analysis following the MCC 1a maneuver.

Webb controllers at the Space Telescope Science Institute in Baltimore, Maryland, perform ranging measurements with the spacecraft using radio signals passed between Webb and ground stations around the world. The data gives engineers information about Webb’s location and speed, allowing navigators to plot future trajectory correction maneuvers. In some cases, they might not be needed, Parrish said.

Another mid-course correction burn, designated MCC 2, is planned 29 days after launch — around Jan. 23 — to inject Webb into its halo orbit around L2.

Webb has four main SCAT engines. One redundant pair is used for the MCC 1a and 1b burns, while the other redundant set is used the MCC 2 maneuver and all subsequent stationkeeping burns to keep Webb in its orbit around L2 during its science mission.

Sixteen smaller thrusters, divided into eight thruster modules each with two engines, are used for pointing control and to offload momentum from the observatory’s six spinning reaction wheels, which steer Webb toward its science targets. The reaction wheels were activated soon after Webb’s launch Saturday.

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

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

The Gimbaled Antenna Assembly, or GAA, includes Webb’s 2-foot-diameter (60-centimeter) high-gain dish antenna. The Ka-band antenna will be used to transmit at least 28.6 Gbytes of science data down from the observatory, twice per day, NASA said.

Ground teams released and tested the motion of the antenna during Sunday’s deployment activity.

Before the release of the Ka-band antenna, Webb communicated to ground teams using a broad-beam S-band antenna at lower data rates. The Ka-band high-gain antenna can downlink data at a speed of up to 3.5 Mbytes per second.

Other steps completed on Webb’s first full day in space included the switch-on of temperature sensors and strain gauges on the telescope, used for monitoring Webb’s thermal and structural parameters, NASA said.

The antenna release and first mid-course correction burn set the stage for the next 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 keep Webb’s telescope and instruments in permanent shade, allowing the optics and detectors to reach a temperature of minus 388 degrees Fahrenheit, or 40 degrees above absolute zero. The super-cold temperatures are necessary for Webb’s infrared instruments to detect faint infrared light from the distant universe.

Two pallets containing the sunshield membranes will fold down from their launch position as soon as Tuesday, if controllers stay on the pre-planned flight schedule. That will allow for the release and tensioning of the sunshield this weekend.

Two wings holding six of Webb’s 18 hexagonal primary mirror segments are expected to fold into place in early January, building the shape of the observatory’s 21.3-foot-diameter (6.5-meter) optical surface. Then comes additional steps to align the mirror and bring it into focus, all while engineers turn on and test each fo Webb’s four science instruments.

But Webb’s time-sensitive commissioning steps — the solar array deployment and first course correction burn — are now complete. Teams have more flexibility in scheduling the remaining commissioning steps over the next six months, culminating in the release of the first science images some time in mid-2022.

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space

News

Webb reaches orbital destination a million miles from Earth

Published

on

Artist’s illustration of the James Webb Space Telescope. Credit: NASA

The James Webb Space Telescope slipped into orbit around a point in space nearly a million miles from Earth Monday where it can capture light from the first stars and galaxies to form in the aftermath of the Big Bang.

As planned, the European Ariane 5 rocket that launched Webb on Christmas Day put the telescope on a trajectory that required only a slight push to reach the intended orbit around Lagrange Point 2, one of five where the pull of sun and Earth interact to form stable or nearly stable gravitational zones.

The push came in the form of a 4-minute 57-second thruster firing at 2 p.m. EST — 30 days after launch at a distance of 907,530 miles from Earth — that increased Webb’s velocity by a mere 3.6 mph, just enough to ease it into a six-month orbit around L2.

“Webb, welcome home!” NASA Administrator Bill Nelson said in a blog post. “Congratulations to the team for all of their hard work ensuring Webb’s safe arrival at L2 today. We’re one step closer to uncovering the mysteries of the universe. And I can’t wait to see Webb’s first new views of the universe this summer!”

Spacecraft at or near L2 orbit the sun in lockstep with Earth and can remain on station with a minimum amount of rocket fuel, allowing a longer operational lifetime than might otherwise be possible.

An orbit around L2 also will allow Webb to observe the universe while keeping its tennis court-size sunshade broadside to Earth’s star and the telescope’s optics and instruments on the cold side.

As of Monday, Webb’s mirror had cooled down to minus 347 Fahrenheit, well on the way toward a goal of nearly 390 degrees below zero. That’s what is required for Webb to register the exceedingly faint infrared light from the first stars and galaxies.

This infographic illustrates Webb’s journey to L2. Credit: ESA

For the rest of its operational life, Webb will circle L2 at distances between 155,000 and 517,000 miles, taking six months to complete one orbit. Because the orbit around L2 is not perfectly stable, small thruster firings will be carried out every three weeks or so to maintain the telescope’s trajectory.

“Congrats to the team!” tweeted NASA science chief Thomas Zurbuchen. “@NASAWebb is now in its new stable home in space & one step closer to helping us #UnfoldTheUniverse.”

Before launch, engineers said Webb likely would have enough propellant to operate for five to 10 years. But thanks to the precision of its Ariane 5 launch and two near-perfect trajectory correction burns carried out later, it now appears Webb could remain operational for many years beyond that.

In any case, with the L2 orbit insertion burn behind then, scientists and engineers will focus on aligning Webb’s secondary mirror and the 18 hexagonal segments making up its 21.3-foot-wide primary mirror to achieve the required razor-sharp focus.

Each mirror segment is equipped with seven actuators, six of which can make microscopic changes in a segment’s orientation and one that can push or pull as required to slightly change a mirror’s shape.

As it now stands, the 18 unaligned segments would produce 18 out-of-focus images of the same star. But over the next few months, the positions of each segment will be adjusted in tiny increments, one at a time, to move reflected starlight to the center of the telescope’s optical axis.

Once all 18 light beams are precisely merged, or “stacked,” Webb will effectively be in focus, clearing the way for instrument calibration. The first science images from the fully commissioned telescope are expected this summer.

Source: Space

Continue Reading

News

Watch live: Cargo Dragon capsule ready to depart space station

Published

on



SpaceX’s Cargo Dragon spacecraft, closing out a month-long mission, is scheduled to undock from the International Space Station Sunday after a two-delay in its departure to wait for better weather in the capsule’s recovery zone off the coast of Florida.

The gumdrop-shaped cargo freighter will undock from the station’s Harmony module at 10:40 a.m. EDT (1540 GMT) Sunday. A series of departure maneuvers using the ship’s Draco thrusters will guide Dragon away from the complex, setting up for a deorbit burn at 3:18 p.m. EDT (2018 GMT) Monday to allow the spacecraft to drop out of orbit and re-enter the atmosphere.

Splashdown in the Gulf of Mexico off the coast of Panama City, Florida, is scheduled for around 4:05 p.m. EDT (2105 GMT) Monday. Four main parachutes will slow the capsule before reaching the ocean, where a SpaceX recovery vessel will be in position to raise the Dragon spacecraft from the sea.

Time-sensitive cargo, such as biological research samples, will be flown back to Kennedy Space Center by helicopter, where NASA researchers will receive and catalog the materials for analysis and distribution to scientists around the world.

The undocking and splashdown will complete SpaceX’s 24th resupply mission to the space station since 2012 under the umbrella of two multibillion-dollar commercial contracts with NASA.

The Dragon spacecraft is packed with more than 4,900 pounds (2,200 kilograms) of cargo, including a spacesuit coming back to Earth for refurbishment after supporting spacewalks outside the space station.

The mission launched Dec. 21 from NASA’s Kennedy Space Center in Florida atop a Falcon 9 rocket. The Dragon cargo freighter docked with the space station Dec. 22, and astronauts began unpacking science experiments, holiday gifts and food, spare parts and other supplies.

The cargo delivery last month hauled 6,590 pounds (2,989 kilograms) of supplies and experiments, including packaging, to the space station’s seven-person crew.

The Dragon cargo ship delivered four experimental CubeSats to the station from teams at Kennedy Space Center, Aerospace Corp., Utah State University, and Georgia Tech. The CubeSats will be robotically deployed outside the complex later this year.

The scientific experiments launched on the SpaceX cargo freighter included an investigation from Merck Research Labs studying monoclonal antibodies. The research focus of that experiment is on analyzing the structure and behavior of a monoclonal antibody used in a drug aimed at treating cancers.

Another experiment is assessing the loss of immune protection in astronauts flying in space.

Proctor & Gamble and NASA have partnered in another experiment to test the performance of a new fully degradable detergent named Tide Infinity, a product specifically designed for use in space.

Astronauts on the space station currently wear an item of clothing several times, then discard the garment. But crews flying to the moon and Mars won’t have the same supply chain of cargo missions to support them.

NASA says Tide plans to use the new cleaning detergent to “advance sustainable, low-resource-use laundry solutions on Earth.”

Another research investigation will test manufacturing methods for superalloys in space. Alloys, materials made up of a metal and at least one other chemical element, could be produced in microgravity with fewer defects and better mechanical properties, according to NASA.

“These superior materials could improve the performance of turbine engines in industries such as aerospace and power generation on Earth,” NASA said.

With its 32-day stay at the station over, the astronauts on the research outpost replaced the cargo delivered by Dragon with materials tagged for return to Earth.

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space

Continue Reading

News

Astra fires up rocket for first time at Cape Canaveral

Published

on

Astra’s small satellite launcher was test-fired at Cape Canaveral’s Complex 46 launch pad Saturday. Credit: Astra / John Kraus

Astra, a company seeking to carve out a segment of the growing small satellite launch market, test-fired its two-stage rocket at Cape Canaveral on Saturday in preparation for an upcoming demonstration flight for NASA.

The engine test-firing, called a static fire test, occurred on launch pad 46 at Cape Canaveral Space Force Station as Astra prepares to deliver four small CubeSat nano-satellites into orbit under contract to NASA’s Venture Class Launch Services program.

The rocket’s five Delphin engines, burning kerosene and liquid oxygen propellants, fired for less than 10 seconds at 11:40 a.m. EST (1640 GMT) Saturday on pad 46.

The static fire test sent an exhaust plume away from the rocket that was visible from public viewing locations several miles away. A low rumble was also heard from the beaches south of Cape Canaveral.

Astra confirmed the static fire test in a tweet Sunday afternoon. Chris Kemp, Astra’s founder and CEO, tweeted that the company will announce the target launch date and time for the mission after receiving a launch license from the Federal Aviation Administration.

The static fire test was expected to be a prerequisite for Astra receiving an FAA launch license.

Astra’s rocket is small in size compared to other launch vehicles that regularly fly from Cape Canaveral. The launcher, called Rocket 3.3 or LV0008, stands just 43 feet (13.1 meters) tall, more than five times shorter than SpaceX’s Falcon 9 rocket, and about the same height as the Falcon 9’s payload compartment.

The commercially-developed launch vehicle, in its existing configuration, is designed to carry a payload of around 110 pounds (50 kilograms) into a 310-mile-high (500-kilometer) polar orbit, according to Kemp. Astra’s rocket is sized to offer dedicated rides to orbit for small commercial, military, and research satellites.



Astra launched its first successful mission to low Earth orbit in November from Kodiak Island, Alaska, on a test flight sponsored by the U.S. Space Force, following three previous launch attempts that faltered during the climb into orbit.

Founded in 2016, Astra aims to eventually conduct daily launches with small satellites at relatively low cost, targeting a smallsat launch market cramped with competitors such as Rocket Lab, Virgin Orbit, and Firefly Aerospace, each of which has begun flying small launch vehicles. Numerous other companies are months or years away from debuting their smallsat launchers.

Four CubeSats are set to ride the rocket into orbit on a mission arranged by NASA.

The mission is part of NASA’s Venture Class Launch Services, or VCLS, program, which awarded Astra a $3.9 million contract last year for a commercial CubeSat launch. Scott Higginbotham, head of NASA’s CubeSat Launch Initiative at Kennedy Space Center, says the agency is the sole customer for the upcoming Astra launch.

The Venture Class Launch Services program is aimed at giving emerging small satellite launch companies some business, while helping NASA officials familiarize themselves with the nascent industry.

NASA previously awarded VCLS demonstration missions to Rocket Lab and Virgin Orbit, which completed their first launches for the U.S. space agency in 2018 and 2021. The U.S. military has awarded similar demonstration launch contracts to Astra and other companies.

Higginbotham said the VCLS mission gives NASA insight into companies’ management and technical teams, procedures and processes, and their hardware designs.

“That’s going to allow us to be a better consumer going forward if they stay in business, and can offer their services to us later on,” Higginbotham said. “We’ll already have been introduced and have done a deep dive, of sorts, into those companies to understand what makes them tick, and that’s that’s of tremendous value to us.”

The VCLS demo missions are also a stepping stone toward certification of the new smallsat launchers to carry more expensive NASA satellites into orbit. The certification isn’t required for the demo missions themselves.

“NASA has other missions that require a little bit more reliability from the launch vehicle, a little more certainty, and a little more launch vehicle insight,” Higginbotham said.

Student teams work on the INCA CubeSat set for liftoff from Cape Canaveral on Astra’s small satellite launcher. Credit: New Mexico State University

A team of fewer than a dozen technicians and engineers set up Astra’s rocket on pad 46 earlier this month. Astra’s launch control team remained behind at the company’s headquarters in Alameda, California, where managers remotely control the rocket’s countdown.

A fueling test, or wet dress rehearsal, was accomplished earlier in January before Saturday’s static fire.

NASA assigned four nano-missions to the Astra demonstration launch through the agency’s CubeSat Launch Initiative program.

One of the CubeSats was developed by the University of California, Berkeley. Named QubeSat, the small spacecraft will test a tiny gyroscope, a device used to help determine the orientation of satellites in space.

Another student-developed payload on Astra’s first launch from Florida is the Ionospheric Neutron Content Analyzer, or INCA mission, from New Mexico State University. INCA’s main science instrument is a directional neutron spectrometer from NASA’s Goddard Space Flight Center.

Data from INCA will “contribute to understanding the radiation environment that satellites encounter, and to the understanding of neutron air showers, which pose a radiation hazard to occupants of high-altitude aircraft such as airliners,” according to the student team that developed the mission.

The BAMA 1 mission, developed at the University of Alabama, will demonstrate a drag sail device designed to help old satellites and space junk drop out of orbit. The drag sail will encounter air molecules from the rarefied atmosphere at the satellite’s altitude, slowing its velocity enough to fall back to Earth.

The final payload is a CubeSat named R5-S1 from NASA’s Johnson Space Center in Houston. NASA says the mission’s objectives including demonstrating quick CubeSat development and testing technologies useful for in-space inspection, which could make human spaceflight safer and more efficient.

Another CubeSat mission from UC-Berkeley originally selected by NASA for the Astra demonstration launch wasn’t ready in time for integration with the rocket in December, according to Jasmine Hopkins, a NASA spokesperson at Kennedy Space Center.

The CubeSat Radio Interferometry Experiment, or CURIE, mission, consists of two identical three-unit CubeSats, each the size of a shoebox, with radio antennas to detect emissions from solar activity, such as solar flares and coronal mass eruptions.

NASA will assign the CURIE satellites to another launch, Hopkins said.

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space

Continue Reading

Trending