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SpaceX launches NASA mission to study dead stars

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SpaceX’s Falcon 9 rocket launches with NASA’s Imaging X-ray Polarimetry Explorer. Credit: Michael Cain / Spaceflight Now / Coldlife Photography

SpaceX launched a refrigerator-sized NASA X-ray observatory from Kennedy Space Center into an unusual orbit hugging the equator Thursday, beginning a $214 million mission to study black holes and super-compact neutron stars.

The successful launch sets the stage for a busy stretch of SpaceX launches before the end of the year, with as many as three Falcon 9 flights planned over a four-day period beginning Dec. 17.

NASA’s Imaging X-ray Polarimetry Explorer, or IXPE, mission is modest in size but promises to open a new window into the structure and behavior of collapsed stellar skeletons, such as black holes and neutron stars.

IXPE launched atop a SpaceX Falcon 9 rocket at 1 a.m. EST (0600 GMT) Thursday from pad 39A at NASA’s Kennedy Space Center in Florida.

Heading due east, the 229-foot-tall (70-meter) launcher climbed through a starry night sky with 1.7 million pounds of thrust from its nine Merlin engines.

Two-and-a-half minutes after liftoff, the Falcon 9 jettisoned its first stage booster and ignited a second stage engine to continue the climb into orbit. The reusable first stage, designated B1061 and making its fifth flight, returned to an on-target landing aboard a football field-sized ship positioned around 400 miles (650 kilometers) east of Cape Canaveral in the Atlantic Ocean.

The second stage, meanwhile, turned off its engine about eight minutes into the mission after placing the IXPE spacecraft into a preliminary parking orbit. A second firing about 29 minutes after launch steered IXPE into its operational orbit about 373 miles (600 kilometers) over the equator.

That set the stage for deployment of the 727-pound (330-kilogram) IXPE spacecraft about 33 minutes after liftoff. Moments later, NASA confirmed the satellite’s solar panels deployed and ground teams established contact with the spacecraft.

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

The IXPE mission is part of NASA’s line of small explorer-class science missions, with cost caps and highly-focused research objectives. IXPE will measure the polarization of X-rays coming from distant cosmic sources, such as black holes, neutron stars, and other objects inside and outside our own Milky Way galaxy.

“IXPE is going to open a new window on the X-ray sky, that of imaging polarimetry,” said Brian Ramsey, the mission’s deputy principal investigator at NASA’s Marshall Space Flight Center in Alabama. “That’s going to give us two completely new measurements that are going to help us understand how some of the most dramatic and energetic events in the universe take place.”

The spacecraft carries three identical X-ray telescopes to focus incoming X-rays onto state-of-the-art detectors supplied by NASA partners in Italy.

“We’re looking at black holes, exploding stars,” Ramsey said. “We’re looking at very intense magnetic fields, a thousand million million times the magnetic field of the Earth. So we’re very excited about this mission. We’re very anxious to get on orbit and start probing the mysteries of these very exotic X-ray sources.”

After separating from the Falcon 9 rocket, IXPE will open its solar arrays and then extend an origami-like boom about a week after launch. The mission’s three X-ray mirror modules are mounted on the tip of the extension, which will give the satellite a length of about 17 feet (5.2 meters) end-to-end.

The mirrors will focus X-ray light back on detectors on the main body of the spacecraft.

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,” said Martin Weisskopf, IXPE’s principal investigator at Marshall. “That’s the degree of polarization, and the direction associated with polarization.”

“Photons come with this exotic property that’s called polarization,” said Luca Baldini, the Italian co-investigator for the IXPE mission from the National Institute for Nuclear Physics in Pisa, Italy. “Polarization has to do with the direction of the plane where the electric field of the X-ray oscillates. When an X-ray interacts with our detector, what happens is the photon disappears and then an electron appears in its place. What we’re trying to do is to follow the footsteps of this electron and reconstruct the direction of emission.”

The information will tell astrophysicists about the extreme environments around black holes and supermassive objects, including the supermassive black hole at the center of the Milky Way galaxy.

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.

NASA’s Imaging X-ray Polarimetry Explorer spacecraft ready for encapsulation inside the payload fairing of its SpaceX Falcon 9 rocket. Credit: NASA

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.”

IXPE will look at a few dozen X-ray sources during its two-year primary mission, Baldini said.

They 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, Ramsey said.

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 satellite will start collecting science data in January after a month-long commissioning phase.

Small IXPE used much of the Falcon 9 rocket’s lift capability

IXPE was the lightest payload ever to get a dedicated launch on a Falcon 9 rocket. Satellites booked for dedicated rides on Falcon 9 missions can weight several tons, but IXPE filled a small fraction of the launcher’s voluminous payload shroud.

Instead of flying on a straight shot east or northeast from Cape Canaveral, as most SpaceX missions do, the Falcon 9 rocket made a hard left turn when it crosses the equator less than a half-hour after liftoff.

The Falcon 9’s second stage engine fired with the rocket flying sideways, maneuvering the IXPE spacecraft into an orbit deviating just 0.2 degrees in latitude on each side of the equator.

The maneuver to change the plane of the satellites orbit, colloquially called a “dogleg,” consumed much of the Falcon 9’s performance capability. A Falcon 9 launching to a similar altitude without the plane change maneuver could loft a payload of more than 30,000 pounds, or 14 metric tons.

Taking into account the plane change, and reserving enough propellant to return the reusable Falcon 9 booster to an offshore landing, the carrying capacity of SpaceX’s workhorse rocket shrinks to a little more than a ton.

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

“We launch due east out of the Cape, and then that would put us in a 28-degree inclination orbit,” said Tim Dunn, NASA’s launch director of the IXPE mission, in an pre-flight interview with Spaceflight Now. “When we hit the equator just off the coast of Africa … we do a pretty significant dogleg to take that 28 degrees out. That’s a significant plane change. But fortunately, we’re looking at about a 330-kilogram spacecraft mass, and we do have a lot of performance on the Falcon 9 rocket.

“We have significant margin, but given the mass that we’re launching, and we all know the Falcon 9 is a very high-performing vehicle, it does take a lot of its performance to zero out that 28-degree inclination.”

During the mission’s preliminary design phase, engineers assumed IXPE would launch on Northrop Grumman’s air-dropped Pegasus XL rocket. The IXPE spacecraft was originally designed to fit inside the Pegasus rocket’s payload fairing envelope.

IXPE needs to fly in an unusual equatorial orbit to minimize the X-ray instrument’s exposure to radiation in the South Atlantic Anomaly, the region where the inner Van Allen radiation belt comes closest to Earth’s surface. That will reduce interference that could affect the sensitivity of IXPE to faint astronomical X-ray sources.

“The inclination is very important to us because, in an equatorial orbit, the cosmic wave background is minimum,” Baldini said. “That’s kind of the best orbit that you can possibly shoot for in terms of the background from charged particles.”

Northrop Grumman’s air-launched Pegasus XL rocket could have sent the IXPE spacecraft into an equatorial orbit from a position over the Pacific Ocean near Kwajalein Atoll, the remote tropical staging point for four previous Pegasus missions.

But SpaceX’s much larger Falcon 9 did the job from Kennedy Space Center, and did it cheaper. SpaceX won a $50.3 million contract in 2019 to launch IXPE on a reused Falcon 9 booster, while Northrop Grumman charged NASA more than $56 million for a Pegasus launch in 2014.

This map shows an illustration of the orbital plane change maneuver accomplished with the Falcon 9 rocket’s second stage to place IXPE into its unique equator-hugging orbit. Credit: SpaceX

The launch of the IXPE mission Thursday marked the 28th flight of a Falcon 9 rocket this year. Three more Falcon 9 missions are on SpaceX’s schedule before the end of 2021.

A batch of Starlink internet satellites is set for liftoff no earlier than Dec. 17 from Vandenberg Space Force Base, California. Then SpaceX will close out the year with a pair of Falcon 9 missions from Florida’s Space Coast — the launch of the Turksat 5B geostationary communications satellite Dec. 18, and the blastoff of a Dragon cargo mission to the International Space Station on Dec. 21.

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Webb closes in on destination with critical mirror alignment on tap

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STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION

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.”

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

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

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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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