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Webb telescope is a ‘time machine’ for astronomers to see the cosmic dawn



The James Webb Space Telescope inside Northrop Grumman’s factory in Redondo Beach, California. Credit: Northrop Grumman

The James Webb Space Telescope, set for launch in the coming days, will look back more than 13.5 billion years in time to see the faint infrared light from the first galaxies, revealing a previously unseen era of cosmic history that shaped the universe of today.

It’s a cosmic time machine, capable of seeing galaxies and stars as they were as few as 100 million years after the Big Bang, the unimaginably violent genesis of the universe.

“This telescope is so powerful that if you were a bumble bee 240,000 miles away, which is the distance between the Earth and the moon, we will be able to see you,” said John Mather, the mission’s senior project scientist at NASA’s Goddard Space Flight Center in Maryland.

“So what are we going to do with this great telescope? We’re going to look at everything there is in the universe that we can see.”

That runs the gamut from the most distant galaxies in the cosmos, to planets, moons, asteroids, and comets in our own solar system. Webb will be able to observe everything from Mars out, seeing details undetected by every other space observatory since Galileo revolutionized astronomy with his first telescope in 1609.

“We want to know how did we get here,” said Mather, winner of the Nobel Prize in Physics in 2006. “The Big Bang, how did that work? So we’ll look. We have ideas, we have predictions, but we don’t honestly know.”

“This is a once in a generation event,” said Pam Melroy, NASA’s deputy administrator. “NASA continues to push the boundaries of what’s possible, and this is such an exciting moment. For centuries, people have looked up at sky and dreamed of trying to understand the big questions. What was the start of the universe? And is there life out there beyond Earth?”

“Webb is going take the blinders off and show us the formation of the universe,” Melroy said. “This telescope represents the kind of public good for science and exploration for which our space program was established.”

Developed over a quarter-century — with concepts dating even earlier — the James Webb Space Telescope is the largest astronomical observatory ever shot into space. Its primary mirror is composed of 18 hexagonal segments, each made of beryllium, coated with a thin layer of gold, and polished to exacting cleanliness standards.

Four infrared instruments are buried inside the telescope, each tuned for a specific job. Together, the instruments will give astronomers their most powerful tool in history.

“Webb will be able to see stars and galaxies 100 times fainter than what was previously possible,” said Klaus Pontoppidan, the mission’s project scientist at the Space Telescope Science Institute in Baltimore, where Webb will be controlled after launch.

Liftoff of the James Webb Space Telescope, a successor to the 31-year-old Hubble Space Telescope, is set for 7:20 a.m. EST (1220 GMT) Saturday aboard a European Ariane 5 rocket from the Guiana Space Center in South America. That’s about 14 years later than scientists in the 1990s hoped the mission — then known as the Next Generation Space Telescope — would be ready to go to the launch pad.

The mission’s launch date slipped repeatedly, and the development cost ballooned to $9.7 billion as engineers struggled with technical problems.

The James Webb Space Telescope inside a Northrop Grumman factory in 2020. The observatory’s primary mirror, made of 18 individual segments, is pictured at center, with part of its sunshield below. Credit: NASA/Chris Gunn

The observatory followed a winding journey to the launch. The mirrors were fabricated, polished, and tested at locations in Ohio, Alabama, California, and Colorado at contractor Ball Aerospace, then transported to NASA’s Goddard Space Flight Center in Maryland for assembly into Webb’s telescope element.

Webb’s four science instruments were delivered to Goddard from the United Kingdom, Germany, California, and Canada. Engineers at Goddard assembled the instruments into Webb’s science module, and started putting together the telescope in 2013.

The telescope was shipped to NASA’s Johnson Space Center in Houston in 2017 for cryogenic testing, then to Northrop Grumman in Southern California for integration with the spacecraft element, which hosts communications and propulsion systems, and the thermal sunshield.

Finally, in October, Webb rode to French Guiana on a French transport ship to begin final preparations for liftoff. Once there, Webb was fueled with rocket propellant and hoisted on top of its Ariane 5 rocket. A Swiss-made payload fairing was lowered over the spacecraft Dec. 17, and the Ariane 5 moved to the launch pad at the tropical spaceport Thursday.

The observatory is named for James Webb, the NASA administrator who helped the space agency for seven years in the 1960s. His tenure was a pivotal time for NASA, during which the first Americans launched into space and plans matured for the Apollo program, which culminated in Neil Armstrong’s first steps on the moon in 1969, less than a year after Webb left the job.

Webb is folded up to fit inside the Ariane 5’s payload shroud. The spacecraft will pop off the top of the Ariane 5 about 27 minutes after liftoff, then begin a series of critical deployments to reconfigure itself into a science-ready discovery machine.

A solar array and steerable antenna will unfurl, then a sunshield will open to the size of a tennis court to start cooling the science instruments and mirrors to an operating temperature of minus 388 degrees Fahrenheit, just 40 Kelvin degrees above absolute zero.

Two articulating wings, each with three of the 18 mirror segments, will swing into place, allowing the primary mirror to reach its final shape. And a boom with the secondary mirror will deploy, lining up just right to bounce light collected by the primary mirror directly into Webb’s instrument module, which houses a suite of sophisticated infrared detectors.

Within a month, Webb will arrive in orbit around the L2 Lagrange point, a gravitationally-stable location nearly a million miles (1.5 million kilometers) from Earth. Ground teams operating Webb using remote control will spend the next five months perfectly lining up the mirrors, bringing the telescope into focus as it settles to its final operating temperature.

In six months, Webb will take its first science images for public release.

The GN-z11 galaxy, pictured by Hubble 400 million years after the Big Bang, against a deep field of galaxies. Credit: NASA/STSCi/Hubble

The mission will see through clouds of dust to study star-forming regions opaque to telescopes like Hubble, which see in the visible part of the light spectrum. The light collecting power of Webb will also allow scientists to measure the chemical make-up of atmospheres on planets around other stars, revealing for the first time which alien worlds might be habitable for life.

And Webb will peer into the universe in search of the first light after the Big Bang some 13.8 billion years ago.

“If you look back over the decades, the questions that defined the telescope we built today are still relevant,” said Mark McCaughrean, a senior advisor at ESA and an interdisciplinary scientist on Webb. “So looking for the very first galaxies and the first stars that formed in the early universe, roughly 100 million or 200 minion years — we don’t know — after the birth of the universe in the Big Bang.

“Those galaxies are not only far back in time and distant from us, but they’re also redshifted,” McCaughrean said.

The universe is expanding, causing light waves to become stretched as they ripple across the cosmos.

“Because of the expansion of the universe, there’s no light in the visible wavelength,” McCaughrean said. “So Hubble has gone back a certain distance, but to see the next step, the even younger galaxies, even closer to the first light, you need an infrared telescope.”

The oldest galaxy spotted by astronomers using Hubble appeared as a faint speck of red. Named GN-z11, the galaxy was observed as it was 400 million years after the Big Bang.

The record established by GN-z11 has stood more than five years, but if all goes well with Webb, is likely to be broken next year or in 2023, according to Swara Ravindranath, a Canadian astronomer working on the Webb mission at the Space Telescope Science Institute.

Hubble, coupled NASA’s Spitzer Space Telescope, revealed the GN-z11 galaxy is a tiny fraction of the size of our Milky Way galaxy, but it churns out stars at a rate about 20 times faster than our galaxy does today. Scientists can determine a galaxy’s age by measuring how much its light is redshifted before reaching our solar system.

This is a Hubble Space Telescope view of a portion of GOODS-South, the southern field of a large deep-sky study by several observatories to trace the formation and evolution of galaxies. The image shows a rich tapestry of 7,500 galaxies stretching back through most of the universe’s history. The farthest galaxies, a few of the very faint red specks, are seen as they appeared more than 13 billion years ago, or roughly 650 million years after the Big Bang. Soon, the James Webb Space Telescope will peer back even farther into this field to trace the formation and evolution of the very first galaxies. Credits: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, and M. Rutkowski (Arizona State University, Tempe), R. O’Connell (University of Virginia), P. McCarthy (Carnegie Observatories), N. Hathi (University of California, Riverside), R. Ryan (University of California, Davis), H. Yan (Ohio State University), and A. Koekemoer (Space Telescope Science Institute)

The stars in the earliest galaxies likely burned hot and fast, consuming their hydrogen and helium fuel within a few million years, the blink of an eye on cosmic time scales. Scientists think the first stars helped fuse together heavier elements, like carbon, nitrogen, and oxygen, that eventually became the building blocks for life.

Astronomers have measured the cosmic microwave background signal from the universe as it was 380,000 years after the Big Bang, before any stars and galaxies were born. The background is like a fingerprint, showing subtle density variations that hint at the complex structures that came later — stars, galaxies, and ultimately massive galactic clusters stretched along filaments in a web of dark matter.

Dark matter, along with dark energy, are the unseen components of the universe. The visible universe, the part made of regular matter we can see and touch, makes up just 5% of the cosmos.

A fog of hydrogen gas spread like a blanket through the early universe, preventing any light from escaping in a period known as the cosmic dark ages. The cosmic expanse finally became transparent as stars lit up, an event poetically called cosmic dawn.

“The Hubble Space Telescope has pushed the limit to 400 million years after the Big Bang,” said Antonella Nota, the European Space Agency’s project scientist for Webb. “There is a gap that Webb has to fill between 400 million years and 100 million years. So there is an entire interval in which we have a baby universe to observe, and Webb will present a view that we’ve never seen before, and it will be just spectacular.”

“This is Webb’s new frontier,” Ravindranath said.

To make its deepest observations, Webb will aim its telescope toward patches of the sky previously seen in Hubble’s famous deep field images.

“Hubble created this extreme ultra deep field,” Pontoppidan said. “It was days and days of exposure time. Webb will do it in a couple of hours in a wavelength range where there’s overlap. Of course, there’s this huge infrared wavelength range where Hubble could not operate, so what we’ll see there, there’s no comparison.”

Webb’s larger primary mirror has six times the light-gathering power of Hubble’s primary mirror. This is important at the longer, dimmer wavelengths of light Webb looks at. Hubble can see some infrared wavelengths, but it was optimized to see shorter ultraviolet and visible light. As observing partners, their observations will complement each other, providing us with views across a broad range of wavelengths.
Credits: NASA, J. Olmsted (STScI)

Astronomers will also use a technique called gravitational lensing to magnify distant galaxies. The technique, pioneered with Hubble, takes advantage of gravitational distortion caused by a massive structure, like a galaxy cluster, between the telescope and its target.

The gravity from the foreground structure can bend the light like a magnifying glass, adding to Webb’s already improved imaging capability.

“With Hubble, we don’t quite have the power to resolve structure in these most distant galaxies,” Ravindranath said. “Webb will be able to show us the very first galaxies and also the earliest stages of galaxy assembly.”

By breaking apart the components of light, Webb will unveil what elements comprised the earliest stars.

“Webb’s infrared spectra will show us the composition of these first galaxies, what type of stars are present, what are the properties of the gas and dust, and what is their chemical composition?”

Finding the earliest galaxies was one of the first major objectives for Webb when astronomers dreamed up the observatory in the 1990s. Webb’s instruments will also trace the evolution of galaxies over the 13 billion years since the first ones formed.

“For almost a century, we’ve been trying to answer this question of how did galaxies form?” Ravindranath said. “How did they evolve over cosmic time, and how did they end up having these regular beautiful spirals that we see in the present day.”

“I think we’re expecting to see galaxies grow over time,” Mather said. “They grow as gravity pulls little bits together.”

Cosmologists will study data from Webb to see how well it matches their understanding of the Big Bang, when the universe came to be in an instant. Much the early history of the universe is in the realm of models, and Webb will add cold, hard data to the mix.

Webb may also see some of the earliest supernovas, the violent explosions at the end of a star’s life. The explosions may have spread heavy elements, such as metals, through the universe to seed the creation of a new generation of stars more like the ones astronomers know today.

The James Webb Space Telescope could image stars in the early history of the universe that formed around primordial black holes. The strong tug of gravity from black holes may have influenced the motion and behavior of the stars. Future missions, like the LISA gravitational wave observatory, will search for signatures created by merging proto-black holes. Credit: ESA

Webb will also search for clues about the first black holes, objects that suck up matter, and even light, with super-strong gravitational fields. Black holes in the present-day universe form after supernova explosions, but they can grow by merging with other black holes.

The largest of these objects, called supermassive black holes, are at the centers of most galaxies, including our own. But there are unanswered questions about the origin of the first black holes.

Primordial black holes may have mysteriously formed immediately after the Big Bang, and then grown over millions of years. If that’s true, the first stars could have been born around the earliest black holes, rather than the other way around.

It’s a classic chicken or egg question played out on a cosmic scale.

“For us, one of the big mysteries is do those stars make the black holes, or do the black holes help make the stars?” Mather said. “So that’s the chicken and egg question we’re really worried about.”

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Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space


Webb closes in on destination with critical mirror alignment on tap




The James Webb Space Telescope with its five-layer sunshade and optical elements fully deployed. Credit: NASA

Thirty days outbound from Earth, the James Webb Space Telescope will slip into its parking orbit a million miles away Monday, an ideal spot to scan the heavens in search of faint infrared light from the first generation of stars and galaxies.

But getting there — and successfully deploying a giant sunshade, mirrors and other appendages along the way — was just half the fun.

Scientists and engineers now have to turn the $10 billion Webb into a functioning telescope, precisely aligning its 18 primary mirror segments so they work together as a single 21.3-foot-wide mirror, by far the largest ever launched.

Earlier this week, the mission operations team remotely completed a multi-day process to raise each segment, and the telescope’s 2.4-foot-wide secondary mirror, a half inch out of the launch locks that held them firmly in place during the observatory’s Christmas Day climb to space atop a European Ariane 5 rocket.

Now fully deployed, the 18 segments currently are aligned to within about a millimeter or so. For the telescope to achieve a razor-sharp focus, that alignment must be fined tuned to within 1/10,000th of the width of a human hair using multiple actuators to tilt and even change a segment’s shape if required.

“Our primary mirror is segmented, and those segments need to be aligned to a fraction of a wavelength of light,” said Lee Feinberg, optical telescope element manager at NASA’s Goddard Space Flight Center. “We’re not talking microns, we’re talking a fraction of a wavelength. That’s what’s tricky about Webb.”

Once aligned and its instruments calibrated, Webb will be 100 times more powerful than Hubble, NASA says, so sensitive to infrared light that it could detect the faint heat of a bumblebee as far away as the moon.

Credit: On Monday, Webb will slip into orbit around Lagrange Point 2 nearly a million miles away where the gravity of the sun and Earth combine to form a pocket of stability where spacecraft can remain in place with minimal amounts of fuel. Credit: NASA

Each mirror segment was ground to a prescription that takes into account the deforming effects of gravity during their manufacture on Earth and their expected shrinkage in the ultra-low-temperatures of space. They were so precisely figured that if one was blown up to the size of the United States, the 14,000-foot-high Rocky Mountains would be less than 2 inches tall.

But if Webb was aimed at a bright star today, the result would be 18 separate images “and they’re going to look terrible, they’re going to be very blurry,” Feinberg said in an interview, “because the primary mirror segments aren’t aligned yet.”

That’s the next major hurdle for the Webb team, mapping out and then tilting each segment in tiny increments, merging those 18 images to form a single exactly focused point of light. It’s an iterative, multi-step process expected to take several months to complete.

But first, the telescope must get into orbit around Lagrange Point 2, 930,000 miles from Earth where the gravity of Sun and Earth combine to form a pocket of stability that allows spacecraft to remain in place with a minimum expenditure of fuel.

It’s also a point where Webb’s tennis court-size sunshade can work to maximum advantage, blocking out heat from the sun, Earth, moon and even warm interplanetary dust that otherwise would swamp the telescope’s sensitive infrared detectors.

As of Saturday, the mirror segments had cooled down to around minus 340 Fahrenheit, well on the way to an operational temperature of around minus 390, or slightly less than 40 degrees above absolute zero.

While the cool-down process continues, a 4-minute 58-second course correction thruster firing is planned Monday at 2 p.m. EST to change the spacecraft’s velocity by a slight 3.4 mph, just enough to put it in a distant orbit around Lagrange Point 2.

If all goes well, the telescope will remain in that six-month orbit for the rest of its operational life, firing its station-keeping thruster periodically to remain on station.

With the orbit insertion burn behind them, engineers will press ahead with mirror alignment, one of the most complex aspects of Webb’s already complicated deployment.

Each 4.3-foot-wide hexagonal primary mirror segment features six mechanical actuators in a “hexapod” arrangement on the back side, allowing movement in six directions. A seventh actuator can push or pull on the center of a segment to ever so slightly distort its curvature if needed.

Webb’s primary mirror is made up of 18 hexagonal gold-coated beryllium segments that must be aligned to within a tiny fraction of the width of a human hair to achieve a sharp focus. This photo shows the mirror during pre-launch preparations with the telescope’s secondary mirror folded away for flight. Credit: NASA

After Webb’s Near Infrared Camera, or NIRCam, cools down to its operating temperature, Webb will be aimed at a bright star so the instrument can map out the reflections from all 18 segments, creating a mosaic showing their relative size and position.

The mirror segments then will be adjusted one at a time, using one actuator then another, to properly aim each one. Additional mosaics will be made as the process continues and depending on the results, the alignment process may have to be repeated.

“The big thing is getting the 18 primary mirror segments pointing in a similar way so that their images are about the same size,” Feinberg said. “Some of them might be very defocused and so you might get a big spot (blurred star image) on segment 5 and a small spot on segment 3.”

The goal is to tilt the segments as required to minimize the size of the defocused images and then to move the multiple reflections to the same point at the center of the telescope’s optical axis, all of them stacked on top of each other to produce a single beam of sharply focused light.

“At the very top level, think of it as 18 separate telescopes aligned to about the same level,” Feinberg said. “And then we will overlap 18 spots on top of each other. We call that image stacking. It is a process of tilting the primary mirror segments so that the images fall on top of each other.”

The key, he said, is “you really need very good control of those actuators, very precise tilts, because we need these 18 spots to overlap each other very well.”

Any given segment can lose one of its six tilt actuators with no impact. Even the loss of a center actuator can be compensated for to some extent by moving the segment up or down slightly.

But exhaustive testing on the ground showed the high-tech actuators are extremely reliable. The procedures were tested before launch using a sub-scale model of the telescope and Feinberg said he’s confident the alignment process will work as planned.

“When will we have an image of a star that’s phased (properly stacked and focused)? I think that’s going to be sometime in March, maybe late March,” he said.

“But then the next question is, when will we have the telescope fully aligned, including the secondary mirror, optimized for all the four instruments? The original plan had us achieving that a full four months into the mission. So that would be like the end of April.”

That still won’t be enough for science observations to commence.

Once the optical system is aligned, the team will focus on testing and calibrating NIRCam, a combination camera and spectrograph, and the telescope’s three other spectrographic instruments, one of which includes the fine guidance sensor needed to keep Webb locked on target.

That process will take another two months or so to complete. Only then will focused “first light” images be released to the public.

“We want to make sure that the first images that the world sees, that humanity see, do justice to this $10 billion telescope and are not those of, you know, hey look, a star,” said Jane Rigby, Webb operations project scientist at Goddard.

“So we are planning a series of ‘wow’ images to be released at the end of commissioning when we start normal science operations that are designed to showcase what this telescope can do … and to really knock everybody’s socks off.”

Source: Space

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Atlas 5 rocket delivers two military inspector satellites to high-altitude orbit



An Atlas 5 rocket, boosted by an RD-180 main engine and one strap-on solid rocket motor, lifts off from pad 41 at Cape Canaveral Space Force Station with a pair of U.S. Space Force tracking satellites. Credit: Alex Polimeni / Spaceflight Now

Two satellites for a once-classified U.S. military program to track and inspect other spacecraft in orbit — a mission the Space Force’s top general equates to a “neighborhood watch” — lifted off from Cape Canaveral Friday on top of a United Launch Alliance Atlas 5 rocket.

Bound for an orbit thousands of miles above Earth, the satellites rode side by side in the Atlas 5 rocket’s payload compartment for the climb into space. The two satellites are the fifth and sixth spacecraft to join the Space Force’s Geosynchronous Space Situational Awareness Program.

The GSSAP satellites lurk near the ring of geosynchronous satellites that fly around Earth at the same speed of the planet’s rotation, allowing craft to remain over a fixed geographic location at an altitude of more than 22,000 miles (nearly 36,000 kilometers). Commercial companies and defense agencies use the orbit for communications, missile warning and signals intelligence missions.

Not only can the surveillance platforms help the Space Force track objects in geosynchronous orbit — a capability needed to manage traffic and avoid collisions — the GSSAP spacecraft can adjust their orbits to approach and image other satellites using sharp-eyed optical cameras.

The GSSAP satellites’ ability to maneuver around other spacecraft gives military officials data on the location, orbit and size of other objects in geosynchronous orbit, according to the Space Force, “enabling characterization for anomaly resolution and enhanced surveillance, while maintaining flight safety.”

“Data from GSSAP uniquely contributes to timely and accurate orbital predictions, enhancing our knowledge of the geosynchronous orbit environment, and further enabling space flight safety to include satellite collision avoidance,” officials wrote in the Space Force’s official GSSAP fact sheet.

The new GSSAP satellites launched Friday join four others deployed into orbit by Delta 4 rockets in 2014 and 2016.

ULA’s launch team at Cape Canaveral loaded the 196-foot-tall (59.7-meter) Atlas 5 rocket with liquid propellants during a trouble-free countdown Friday, culminating in startup of the first stage’s Russian-made RD-180 engine and ignition of a single strap-on solid-fueled booster at 2 p.m. EST (1900 GMT).

The two powerplants combined to produce about 1.2 million pounds of thrust, five times the thrust of a Boeing 747 jumbo jet at full throttle, to propel the Atlas 5 rocket through a thin overcast cloud layer and downrange east from Cape Canaveral.

Two minutes after liftoff, the Atlas 5 shed its single Northrop Grumman-built strap-on booster. Three-and-a-half minutes into the mission, the Atlas 5’s payload fairing jettisoned to reveal the mission’s two U.S. Space Force satellites after climbing above the atmosphere.

The RD-180 first stage engine shut down nearly four-and-a-half minutes after liftoff, and the single-use bronze-colored booster stage separated to fall into the Atlantic Ocean. A Centaur upper stage, powered by an Aerojet Rocketdyne RL10C-1 engine, ignited a burn lasting more than eight minutes to reach the required velocity to enter orbit around Earth.

The Centaur stage fired two more times — at T+plus 1 hour, 9 minutes, and at T+plus 6 hours, 30 minutes — to maneuver the GSSAP satellites into their targeted deployment orbit at an altitude of 22,440 miles (36,113 kilometers) over the equator.

The satellites separated from the Centaur upper stage one at a time, and ULA confirmed the final spacecraft separation event at 8:45 p.m. EST Friday (0145 GMT Saturday).

The GSSAP satellites, built by Northrop Grumman, were expected to open their solar panels soon after separating from the Centaur upper stage. Friday’s mission, officially designated USSF 8, was the first launch by ULA this year, and the 91st flight of an Atlas 5 rocket since its inaugural launch in August 2002.

“ULA continues to launch national security assets into highly complex orbits,” said Gary Wentz, ULA’s vice president of government and commercial programs. “The USSF 8 mission was successfully delivered to near-geosynchronous orbit after a nearly 7-hour mission.”

The GSSAP program, which was classified until 2014, produces data that helps military and other government satellites “navigate freely and safely” in geosynchronous orbit, according to the Space Force’s Space Systems Command.

Artist’s concept of two GSSAP spacecraft in orbit. Credit: U.S. Space Force

“The first four GSSAP satellites have performed remarkably well,” said Lt. Gen. Stephen Whiting, commander of Space Operations Command. “These next two satellites will add to that capability and enable us to understand more completely things that occur in the geosynchronous orbit. It’s a key piece in the puzzle for space domain awareness.”

The new GSSAP satellites will become sensors in the Space Force’s Space Surveillance Network, which tracks more than 27,000 satellites, derelict rockets, and other pieces of space junk circling Earth.

“The way I describe it is a neighborhood watch capability,” said Gen. John “Jay’ Raymond, the chief of space operations and the highest-ranking officer in the Space Force. “It allows us to better understand what’s going on in the domain, especially in a really critical orbit like geosynchronous orbit.”

Before the establishment of the Space Force, the Air Force sent one of the GSSAP satellites to the aid of a crippled U.S. Navy communications satellite in 2016. The Navy’s fifth MUOS relay satellite ran into propulsion trouble after launch, forcing it to use backup thrusters to climb into its perch in geosynchronous orbit.

The GSSAP satellite changed course to capture imagery of the MUOS 5 spacecraft to give engineers insight into its status and condition, the Air Force said at the time.

“Historically, the way we have surveilled or had awareness of the domain is we’ve taken observations from radars or optical capabilities, and we’ve come up with an address in space, if you will, of objects,” Raymond said Tuesday in a virtual discussion hosted by the Mitchell Institute.

Cataloguing satellites and space debris has been the a chief goal of the military’s space-related efforts for decades. But with countries like China and Russia fielding increasingly sophisticated military spacecraft, including anti-satellite capabilities, the Space Force needs the GSSAP satellites to add a new dimension in its tracking of objects in orbit.

“We’ve been worried about making sure two things don’t collide, that we can keep that domain safe for all, which is critical. But it’s not sufficient,” Raymond said. “If you move into a war fighting domain, you have to have more knowledge than just where something is. You have to have some insights into what those capabilities are, and this neighborhood watch capability has provided us a fuller look at what’s in space, specifically in the geosynchronous domain.”

The fifth and six satellites will provide “additional capacity” for the GSSAP network to better cover the large volume of space in the geosynchronous belt, Raymond said in response to questions from Spaceflight Now.

The Atlas 5 rocket’s single solid rocket booster and RD-180 main engine power the launcher into an overcast sky Saturday over Cape Canaveral. Credit: Michael Cain / Spaceflight Now / Coldlife Photography

The rocket used to launch the fifth and sixth GSSAP satellites debuted a new configuration of ULA’s workhorse Atlas 5. The variant combined a single solid-fueled booster with a a 5.4-meter (17.7-foot) diameter payload fairing provided by RUAG Space, and a single RL10 engine on the Centaur upper stage.

This version of the Atlas 5 is known as the “511” configuration, with the first number denoting the size of the payload fairing, the second number representing the number of solid rocket booster, and the third digit the number of engines on the Centaur stage.

The placement of just one strap-on booster on the side of the Atlas 5’s first stage will give the rocket asymmetrical thrust as it climbs off the pad. Atlas 5 missions have flown with a single solid rocket booster before, but those flights used the smaller 4-meter-wide payload fairing option.

The Atlas 5-511 rocket will take off with 1.2 million pounds of thrust from the single solid-fueled booster and the first stage’s kerosene-fueled RD-180 main engine. According to ULA, the Atlas 5-511 can carry up to 11,570 pounds (5,250 kilograms) to an elliptical geostationary transfer orbit. Its capacity to low Earth orbit is roughly 24,250 pounds (11,000 kilograms), according to ULA performance data.

Tory Bruno, ULA’s CEO, calls the “511” version of the Atlas 5 the “Big Slider” because the asymmetrical thrust causes the rocket to “power slide off the pad.”

The launch Friday was the only planned flight of the Atlas 5-511 configuration as the Atlas 5 family nears retirement.

“That nozzle (of the solid rocket booster) is canted to pass through the average center of gravity, and the RD-180 has tremendous control authority with its thrust vector system, and it can overcome that and compensate for it, and this is just the right amount of energy to carry these two payloads to their very cool mission of space surveillance,” Bruno said.

The Atlas 5 rocket was designed by Lockheed Martin to fly in up to 20 different configurations, giving engineers the ability to “dial” the rocket’s power and payload volume to meet the needs of each specific mission. Mission planners have the option of flying a four-meter or five-meter diameter payload fairing, and can fly the Atlas 5 with up to five strap-on solid boosters, or none if the mission doesn’t need them.

The Atlas 5’s Centaur upper stage can fly with one or two RL10 engines, depending on mission requirements. So far, all but one Atlas 5 launch has flown with the single-engine Centaur upper stage.

The exception is on launches with Boeing’s Starliner capsule, which launches with a dual-engine Centaur stage. There are no other missions on the Atlas 5 launch schedule confirmed to use the dual-engine Centaur stage.

The addition of the unique Atlas 5 configuration for Starliner missions and the lack of use of other dual-engine Centaur variants effectively leaves 11 Atlas 5 versions that will have flown at least once before the rocket’s retirement.

Lockheed Martin merged its Atlas rocket program with Boeing’s Delta family in 2006 to create United Launch Alliance.

The most-used version of the Atlas 5 to date is the “401” variant with a four-meter fairing and no solid boosters. The Atlas 5-401 has flown 40 times, including the first Atlas flight in 2002.

There have been six flights of the Atlas 5-411 configuration with a sole solid booster.

With asymmetrical thrust countered by steering from the Atlas 5’s RD-180 main engine, the Atlas 5-511 and -411 configurations are unique among launchers currently in service. The ability to add a single booster allows customers to pay for just enough capacity for their payloads, rather than buying a more larger, more expensive Atlas 5 variant.

ULA is developing the upgraded Vulcan Centaur rocket to replace the Atlas and Delta rocket families.

There are 25 more Atlas 5 rockets remaining in ULA’s inventory, following the launch Friday afternoon. All have been allocated to future missions for the Space Force, NASA, and Amazon’s Kuiper internet satellite constellation.

There are just three Delta rockets left to fly, and all are assigned to carry classified cargo into orbit for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

ULA’s next mission is set for liftoff March 1, when another Atlas 5 will carry a weather satellite into orbit from Cape Canaveral for the National Oceanic and Atmospheric Administration, or NOAA.

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Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space

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Science mission begins for NASA’s new eye on the X-ray universe



Artist’s concept of the Imaging X-ray Polarimetry Explorer. Credit: NASA

A NASA astronomy satellite that launched Dec. 9 from Kennedy Space Center on a SpaceX rocket has started observing the X-ray universe, beginning a mission to study the nature of black holes and the super-dense skeletons left behind by exploded stars.

The Imaging X-ray Polarimetry Explorer, or IXPE, mission launched Dec. 9 aboard a SpaceX Falcon 9 rocket, which delivered the satellite to a unique equatorial orbit at an altitude of about 373 miles (600 kilometers).

After separating from the Falcon 9 launcher, the 727-pound (330-kilogram) IXPE spacecraft unfurled its solar panels and sailed through a series of tests. On Dec. 15, less than a week after launch, IXPE extended an origami-like boom holding the satellite’s three X-ray telescopes, giving the satellite a length of about 17 feet (5.2 meters) end-to-end.

The extendable boom is the right length to allow the telescopes’ mirrors to focus X-ray light back on detectors inside the main body of the spacecraft, giving IXPE satellite the ability to register high-energy waves emitted from black holes, neutron stars, and X-ray sources invisible to telescopes tuned to observe in other wavelengths.

“The commissioning has been successfully completed,” said Martin Weisskopf, IXPE’s principal investigator from NASA’s Marshall Space Flight Center in Huntsville, Alabama. “The two most nerve-racking elements of the commissioning were the solar panels deploying and the boom deploying.”

With the boom extension complete, ground teams spent about three weeks checking the observatory’s maneuvering and pointing capabilities and aligning the telescopes, according to NASA.

“All spacecraft functions have been activated and verified during commissioning,” Weisskopf said in a Jan. 10 press briefing at an American Astronomical Society meeting.

This image from NASA’s Chandra X-ray Observatory shows Cassiopeia A, the remnants of a star the exploded in a violent supernova event around 350 years ago. NASA’s IXPE mission is observing Cassiopeia A as its first scientific target. Credit: NASA/CXC/SAO

IXPE is one of several X-ray astronomy missions in NASA’s portfolio, but it’s the first tuned to measure the polarization signal of X-ray light. Previous telescopes, which must in space to detect cosmic X-rays, have imaged X-ray sources in high angular resolution, measured their spectroscopy, or chemical fingerprints, and studied the time variation of X-ray signals.

“By doing this mission, we are adding two variables to the astrophysics toolkit to understand these sources,” Weisskopf said before IXPE’s launch. “That’s the degree of polarization, and the direction associated with polarization.”

The polarization of X-ray light a measurement of the direction of its electromagnetic field, a telltale signal that can inform astrophysicists about the extreme environments around black holes and supermassive objects, including the supermassive black hole at the center of the Milky Way galaxy.

Weisskopf said Jan. 10 that IXPE’s detectors, which are the first designed to measure X-ray polarization from space, observed bright calibration sources with known properties to help ground teams fine-tune the alignment of the missions’s telescopes.

IXPE’s three identical telescopes can measure the energy, position, time of arrival, and polarization of each X-ray photon they collect.

Satisfied that the IXPE mission is ready for its science campaign, NASA managers gave the green light for the spacecraft to begin the first of its regular astronomical observations Jan. 11.

IXPE’s first target is named Cassiopeia A, or Cas A, a giant debris cloud surrounding a super-dense neutron star around 11,000 light years away. Cassiopeia A formed around 350 years ago, when a star estimated to be five times more massive than the sun exploded in a violent supernova.

The explosion sent matter from the star’s interior out into space in all directions at nearly the speed of light, leaving behind the star’s collapsed core, a neutron star. IXPE’s observations will yield insights into the magnetic field surrounding the neutron star.

The observatory will observe Cassiopeia A for about three weeks. It’s the first of 33 planned science targets selected for the first year of IXPE’s mission, Weisskopf said.

Nine Merlin main engines power SpaceX’s Falcon 9 rocket off pad 39A on Dec. 9 with NASA’s IXPE mission. Credit: Michael Cain / Spaceflight Now / Coldlife Photography

Mission planners have also set aside observing time for IXPE to turn its telescopes toward “targets of opportunity,” such as features or objects that suddenly brighten in the sky, Weisskopf said. “So if something interesting comes up, we can go and look at it.”

The flight plan has time for observations of about 40 targets overall in IXPE’s first year of operations. IXPE will aim its telescopes at each targets for days or weeks at a time, collecting long X-ray exposures to allow scientists to sort out polarized signals from background noise.

NASA is funding IXPE for a two-year primary mission, which the agency says adds up to $214 million, including development, the launch, and operations. The spacecraft doesn’t need any rocket fuel for pointing or orbital maneuvers.

IXPE is a partnership between NASA and the Italian Space Agency, which provided the mission’s X-ray detectors and a ground station Kenya to receive science data from the satellite when it flies overhead.

According to Weisskopf, X-ray polarization can tell scientists about the spin of a black hole. Theoretical calculations show that the degree of polarization of an X-ray signal varies with the energy of the magnetic field at its source.

“Black holes don’t have many properties, but one of them is spin,” he said. “So this is a very fascinating use of the polarimetry to determine something about the nature of its source, and that story holds true in many other cases.”

Other targets for IXPE include the supermassive black hole at the center of our galaxy, known as Sagittarius A*. IXPE’s measurements may confirm whether the black hole was much brighter just a few hundred years ago, as some scientists believe.

IXPE will also look at more distant targets, such as blazers at the centers of other galaxies. Blazars have powerful jets of radiation that happen to be aimed directly at Earth.

The mission will also study the polarization of X-rays coming from magnetars, which have the strongest magnetic fields of any star, some one thousand trillion times more intense than Earth’s magnetic field.

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Source: Space

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