Home / Science / Atlas 5 starts deploying a highly secure military communications network – Spaceflight Now

Atlas 5 starts deploying a highly secure military communications network – Spaceflight Now



An Atlas 5 rocket fired from Pad 41 in Cape Canaveral at 4:18 p.m. EDT (2018 GMT) Thursday. Photo credit: United Launch Alliance

The sixth and final satellite in the U.S. military’s safest satellite communications fleet launched on Thursday with a missile from Cape Canaveral’s United Launch Alliance Atlas 5 and extended the expected lifespan of the network beyond 2030.

The 60-meter Atlas 5 rocket fired from Pad 41 at Cape Canaveral Air Force Station at 4:18 p.m. EDT (2018 GMT) Thursday. The fiery start of the mission was delayed by more than an hour for ULA teams to resolve an issue with a ground hydraulic controller that triggered a last minute break at the first countdown of the day.

The technical issue was resolved before Thursday’s two-hour launch window ended, and the countdown continued for another attempt. At T-minus 2.7 seconds the kerosene-powered RD-180 engine of the rocket came to life, seconds later the firing of five strapped solid rocket boosters followed.

The Atlas 5 climbed off the launch pad with around 2.6 million pounds of thrust and turned eastward across the Atlantic with the U.S. Military’s sixth Advanced Extremely High Frequency communications satellite.

The carrier’s boosters – manufactured by Aerojet Rocketdyne – burned out and dropped less than two minutes after launch, followed by the separation of the Atlas 5’s payload fairing made in Switzerland. The main engine built in Russia became four and a half minutes after the mission began the first stage of the Atlas 5 turned off, and seconds later the stage separated.

The Centaur upper stage of the Atlas 5 fired its RL10C-1 engine for the first of three burns to put the AEHF 6 satellite into a unique orbit on the way to a final operating position of more than 22,000 miles (almost 36,000 kilometers) to inject high altitude. over the equator.

The mission on Thursday was the 500th production RL10 engine to be flown. RL10 engines, which burn liquid hydrogen and liquid oxygen propellants, have flown with Atlas, Saturn and Titan rockets and have sent spaceships to every planet in the solar system.

After the centaur’s second fire – about half an hour after launch – the rocket released a small suitcase-sized CubeSat secondary payload called TDO 2.

The TDO 2 spacecraft, sponsored by the Air Force Research Laboratory and manufactured at the Georgia Institute of Technology, is based on a 12U CubeSat design. According to the Space Force’s Space and Missile Systems Center, its mission will support “space domain awareness” through optical calibration and satellite laser removal.

After deploying the TDO 2 payload, the Centaur idled for five hours before firing the RL10 engine for the third time to reshape the rocket’s orbit. The final RL10 combustion took place at an altitude of around 35,000 kilometers.

The planned 88-second combustion increased the perigee or the low point of the orbit and reduced its inclination. The maneuver brought the AEHF 6 spacecraft closer to its orbit, reducing the satellite’s expected fuel consumption and extending its useful life.

At 9:59 p.m. EDT (0159 GMT), the Centaur stage, the spacecraft AEHF 6 released. Minutes later, satellite builder Lockheed Martin confirmed that ground teams received signals from the new satellite.

“We are very pleased to reach this important milestone on the last AEHF satellite,” said Col. John Dukes, senior material manager for the geosynchronous orbit department of the SMC production corps. “The combined integrated team worked diligently to ensure the success of this mission. The satellite is working as expected and is ready to perform an orbit increase and on-orbit testing over the next few months. After that, he will offer our war fighters critical business skills. “

The AEHF 6 satellite was encapsulated in the payload fairing of the Atlas 5 rocket in February before launch on Thursday. Photo credit: United Launch Alliance

The successful launch on Thursday was the first deployment of a U.S. space force payload since the formal establishment of the new military service in December. The AEHF satellites were previously managed by the Air Force, and the first five were launched from Cape Canaveral in August 2010 using Atlas 5 rockets.

The Space Force remains part of the Air Force, but the new service took over units that were formerly under the authority of Air Force Space Command.

“Congratulations to the US Space Force on launching its first mission,” said Tory Bruno, president and CEO of ULA, in a statement. “We are proud to be your partner for this historic mission and are honored to have launched the entire AEHF constellation produced by Lockheed Martin on Atlas 5 rockets. We know how important it is to provide protected communications for strategic commands and tactical warfighters operating on land, sea and air. “

U.S. military satellite tracking data showed that the AEHF 6 spacecraft was separated from the Centaur upper stage in an elliptical transfer orbit between 6,767 miles (10,891 kilometers) and 21,492 miles (35,313 kilometers) with a slope of 13.7 degrees to the equator .

These orbital numbers were very close to the pre-launch predictions. The final combustion of the RL10 prior to deployment of the AEHF 6 satellite was programmed to continue until the sensors at the Centaur level detect low fuel levels to ensure that the payload reaches the best possible orbit.

The AEHF 6 satellite will use its own engine and plasma engines to maneuver into a circular geostationary orbit more than 22,000 miles above the equator, where the vehicle’s speed will match Earth’s rotational speed. This enables AEHF 6 to stay in the same part of the world 24 hours a day.

Military officials have not disclosed the geographic coverage area for AEHF 6.

The AEHF satellites are designed to operate for at least 14 years and are linked to the Milstar satellite network of the Air Force.

Each of the AEHF satellites, distributed around the world to enable global coverage, offers more capacity than the entire Milstar constellation with five satellites that was launched in the 1990s and 2000s. The AEHF satellites are networked with one another so that the network can transmit signals all over the world without passing through a ground station.

AEHF 6 will go live as soon as it passes post-launch tests, Space Force officials said.

The AEHF satellites offer connectivity with different specified data rates between 75 bits per second and 8 megabits per second. These data rates are slow by modern standards, but what distinguishes the AEHF satellites is their ability to withstand interference and continue to work even in the event of a nuclear war.

Each satellite also has gimbal antennas to reach users on the go. Phased array antennas with beams can be controlled electronically rather than mechanically, and according to users in the theater, zero antennas offer “extremely high anti-jam capability” Northrop Grumman, provider of the AEHF communication payload.

“If AEHF were to operate in the mode (with the highest bandwidth), the President of the United States, national leaders and four international allies could be able to communicate in speech-recognizable communication at every event.” Dukes said.

The governments of Australia, Canada, the Netherlands and the United Kingdom have joined the AEHF program.

“Worldwide we have numerous army, navy, air force and joint international partner terminals online with the AEHF constellation,” said Dukes. “We have enough bandwidth to serve all terminals in our operating concept. By upgrading from Milstar to the AEHF constellation, we can now provide this function until after 2030. “

Thursday’s launch took place amid the coronavirus pandemic that has delayed many upcoming launches.

However, the launch of the AEHF 6 satellite was rated as critical by military leaders.

“There are critical or important things the US Department of Defense does every day, regardless of the current global situation,” said Lt. Gen. John “JT” Thompson, commander of the Space and Missile Systems Center at Los Angeles Air Force Base. “Even in the face of a global pandemic like the COVID 19 crisis, we still have important tasks to do.

“One of these mission-critical tasks, one of the tasks we need to do for the Warfighter and the United States, is the launch of AEHF 6,” said Thompson. “It’s called missionary, and that’s because the AEHF constellation supports the President of the United States, other national leaders, and the common forces in critical strategic communication around the planet.”

“This particular launch extends this capability into the 2030 period,” said Thompson.

According to ULA, the next launch of Atlas 5 is scheduled for May, when the next flight of the military’s X-37B spacecraft is to take off from Cape Canaveral.

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Follow Stephen Clark on Twitter: @ StephenClark1.




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