On their third flight on Monday night, SpaceX's Falcon Heavy rocket will fly three different orbits on a mission lasting more than six hours on two challenging spacecraft on a difficult mission of all time.
The three-core rocket, consisting of the combination of three Falcon 9 boosters on a single launcher, is scheduled to launch from Pad 39A during a four-hour launch window at 11:00 am at NASA's Kennedy Space Center in Florida: 30:00 EDT Monday ( 03:30 GMT Tuesday).
There is a 70 percent chance of favorable weather during the nighttime window, which officials have selected to meet the thermal demands of the payloads as they travel into orbit.
It will be the first night launch with the SpaceX missile Falcon Heavy, currently the world's most powerful rocket. The 27 Merlin main engines of the rocket will propel the rocket with 5.1 million pounds of thrust, almost twice as much as any other launcher.
In addition, the rocket's two side boosters will be back in Cape Canaveral minutes later. The fiery start and the fiery landing at night in conjunction with the roar of the 27 main engines of the Falcon Heavy and the crackle of the supersonic blasts on the return of the booster will be an unavoidable spectacle for space enthusiasts and residents, if the weather permits.
SpaceX completed a trial run before Pad 39A on Wednesday night and then returned the rocket to its hangar on Friday to receive its 24 satellite payloads. The research and weather observation satellites come from the US Air Force, NASA, NOAA, universities, international partners, and nonprofit organizations.
The Air Force monitors the launch by the Defense Department's Space Test Program, a unit that organizes rides to space for the experimental satellites of the military.
The mission is called STP-2.
"STP-2 is the government's first launch of a SpaceX Falcon Heavy vehicle and one of the most challenging missions, Space and Missile Systems Center has ever been launched," said Col. Robert Bongiovi, Director of Start Enterprise Systems at SMC. "We are placing 24 research and development satellites in three separate orbits, with the second stage being started and fired for the first time with four engines."
SpaceX founder and CEO Elon Musk agrees, calling STP-2 SpaceX's "Most Difficult Start Ever".
"Every launch is unique, and this one is definitely unique, with so many deployments in many different orbits," said Mike Marlow, STP-2 mission manager of the Space Test Program at Kirtland Air Force Base, New Mexico.
SpaceX has never fired an upper stage engine more than three times in space as part of the primary mission of a rocket.
The STP-2 mission has a total financial value of approximately $ 750 million, including Air Force-acquired satellites and the SpaceX launch service, Marlow said. However, this is a rough estimate as the satellites come from several governmental and international institutions that track finances in different ways.
Falcon Heavy to Launch in Three Different Orbits
During the weekend, SpaceX staff removed a trial of the Falcon Heavy's payload fairing, which was installed during static fire tests to collect acoustic data. Mission satellite payloads, which were already enclosed in a flight-ready disguise, were to be rocketed to Pad 39A before launch on Monday night.
After a transporter had driven up the ramp to Pad 39A, the Falcon Heavy is raised vertically for the final countdown preparations and refueling on Monday night.
A computer-controlled countdown sequencer monitors the loading of nearly 3 million pounds of highly-cooled kerosene and liquid oxygen into the three first-stage boosters of the Falcon Heavy and upper levels.
After the last steering controls and pressurization of the rocket's fuel tanks, computers give orders for the Falcon Heavy to fire its engines in the last 10 seconds after the countdown. Hold-down clamps at the base of the rocket release, allowing the Falcon Heavy to climb into the sky.
The Falcon Heavy turns exactly east of Florida's space coast, towering over the Atlantic and the speed of sound in about a minute.
About two and a half minutes after takeoff, the side amplifiers are disconnected and disconnected from the Falcon Heavy core to launch a series of propulsion maneuvers directing the twin rockets back to the landing zone 1 and landing zone 2 at the Cape Canaveral Air Force Station.
The rockets hit the landing pad almost simultaneously from the edge of space, about 15 kilometers south of Pad 39A.
Monday night's mission is the first time SpaceX has landed two rocket boosters at the same time. The Side Boosters both flew on the previous Falcon Heavy mission with the Arabsat 6A commercial communications satellite when they landed on Cape Canaveral on April 11.
"As long as there are no clouds but have been down there for a few years, the rest on land will be a spectacular sight as they return to the landing zone," said Walter Lauderdale. the STP-2 Mission Director of the Falcon Systems and Operations Division of SMC.
Following the release of the side amplifiers, the central core of the Falcon Heavy throttles its engines to full power. The core stage will be operated in the first few minutes of the mission to save fuel with partial power.  About three and a half minutes after takeoff, the core stage will shut off their engines and disassemble to launch their own controlled descent to the SpaceX offshore drone ship, which is located nearly 1,240 kilometers east of Cape Canaveral. The salvage ship is further away than parked on previous SpaceX missions, and the Falcon Heavy core sinks faster than any previous booster.
The core level aims to land on the drone ship about 10 minutes after the start of the mission. shortly after putting on the side boosters of the Falcon Heavy. The core stage, which flies on Monday night, is a new booster.
The core stage of Falcon Heavy's first launch in February 2018 crashed on landing, and Falcon Heavy's second mission mid-boost in April successfully landed, but toppled before it could be secured for return to port.
But the mission will not begin until the three Falcon Heavy boosters are back on Earth.
The second stage of the rocket, powered by a single Merlin engine, will fire four times on the long flight.
The first blast will move the Mission's 8,157 lb (3,700 kg) payload stack into a near-earth orbit, where 13 satellites will be dropped off adapters on the upper Falcon Heavy.
The first orbital target for the STP-2 mission is at a height of between 300 km and 860 km. The first orbit will have a slope or incline of 28.5 degrees to the equator.
The first payload released by Falcon Heavy is Oculus-ASR, a microsatellite developed by Michigan Technological University students in collaboration with the Luftwaffe Research Laboratory. Oculus ASR will test the ability of ground-based observers to determine the orientation and configuration of a satellite in orbit using unresolved imagery.
According to Marlow, Oculus-ASR will break away from the carrier about 13 minutes after taking off, followed by the ejection of 12 CubeSats.
A second shot of Falcon Heavy's top stage engine will direct the rocket into a circular orbit about 720 kilometers above the earth at 24 degrees closer to the equator.  Artist concept of the STP-2 payloads on the upper stage of the Falcon Heavy. Credit: SpaceX
Six weather satellites, developed by NOAA and Taiwan's space agency, will separate with the launch vehicle's 447-mile orbit along with several other microsatellites.
The Constellation Observation System for Meteorology, Ionosphere and Climate Mission -2 or COSMIC-2 will form a weather observation network that collects temperature, pressure, density and water vapor data in various layers of the Earth's atmosphere.
Other satellites to be deployed on the Mission's second orbit are the Orbital Test Bed spaceship built by General Atomics. The Orbital Test Bed (OTB) mission hosts several payloads, including NASA's Deep Space Atomic Clock experiment, which is designed to test a new type of hyper-accurate atomic clock that could facilitate the navigation of space probes.
Another package attached to the OTB satellite contains the cremated remains of 152 people, including deceased astronaut Bill Pogue and space journalist and historian Frank Sietzen. The payload Celestis calls "heritage flight" will remain in orbit around the OTB spacer for about 25 years.
NASA's mission to infuse green propellants will also be deployed on 447-mile orbit. The mission was built by Ball Aerospace with an Aerojet Rocketdyne propulsion system and is testing a new type of non-toxic "green" propellant that could be used in future satellites to replace hydrazine, a corrosive fuel commonly used in spacecraft it can be stored for Yars at room temperature.
A satellite called NPSAT 1, which was developed at the Naval Postgraduate School, will also split in the second orbit of the Falcon Heavy. NPSAT 1 has two instruments from the Naval Research Laboratory for measuring electron density in the Earth's ionosphere, a layer high above the Earth that affects radio communication over long distances. Engineers will also use the microsatellite to test a radiation-tolerant computer processor, experimental solar cells, and low-cost storage devices, speed sensors, and a commercial digital camera.
Georgia Tech's Prox-1 microsatellite is the other satellite in suitcase size planned for use in the second orbit of the STP-2 mission. Prox-1, which is also funded by the Air Force Research Laboratory, will provide approximation operations and inspection techniques after the release of a subsidiary satellite called LightSail 2, a Planetary Society crowd-funded cube satellite that will demonstrate the propulsion capabilities of an aircraft Orbit test awning, which uses the pressure of sunlight for the thrust.
After the microsatellites have been dropped, the Falcon Heavys upper tier is re-fired twice to achieve a higher altitude and a higher propensity for use of the final payload – the Air Force Research Laboratory's demonstration and Science Experiments (DSX), spacecraft.
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The DSX satellite will fly with instruments in a slot area between the Van Allen radiation belts to measure the effects of very low frequency radio waves on space radiation, space weather conditions and the impact of radiation on electronics and spacecraft materials.  "Space has never been as important to our nation as it is today," said Major General William Cooley, commander of the Luftwaffe Research Laboratory. "The DSX satellite experiment will greatly enhance our understanding of the spacecraft environment in which we operate and provide us with the knowledge to build even better satellites to protect and defend our space assets. I am very proud of the AFRL scientists, engineers and technicians who designed and built the DSX satellite. "
DSX orbits the earth in a unique orbit between 6,000 kilometers and 12,000 kilometers altitude with a 42 degree inclination to the equator. According to Marlow, the DSX is the heaviest single-spaceship on the STP-2 mission, with a takeoff weight of about 1,540 pounds or about 700 kilograms.
A series of NASA experiments will be conducted on the DSX satellite to help scientists measure how radiation can damage spacecraft storage equipment and damage electrical circuits.
If DSX is not near the missile, the Falcon Heavy's upper stage is "passivated" or placed in a safe configuration by throwing the missile's remaining propellant overboard. Passivation marks the end of the STP-2 launch sequence, which will take six to seven hours from start to finish, according to SpaceX and the Air Force.
STP-2 maximizes lift of Falcon Heavy capacity paves the way for further military launch
The mission will push the Falcon Heavy to its limits and SpaceX and the Air Force allow to collect data to ensure that the rocket is ready to lift the most expensive military payloads of national security into orbit.
"By volume, payloads occupy about a third, perhaps just over a third of their payload fairing," Marlow said. "But in terms of performance, since we're driving three different orbits, it actually takes all of Falcon Heavy's performance."
"They're giving back all three boosters," Bongiovi said. "Part of the rocket's performance is needed for that. In this way you reduce the amount of payload that you can start technically. The same applies to the orbit changes, the four burns, and the way we put these satellites into different orbits, which affects the amount of mass that can get to each of these orbits. "
" Even if the first The orbit is a parking track. You still need to sit there and take a break while using all the satellites, and then restart the second stage to get to the next orbit.
also affects the launcher's performance as it gets colder on the orbit, "he said. "There are many parameters that really go into the whole performance calculation. This entire mission is over seven hours long, which means a launcher must operate long in orbit.
The satellites aboard the STP-2 mission are unique and valuable, but all experimental. The Air Force has launchers designed to upgrade reconnaissance, communication and navigation payloads to a higher standard.
The Air Force announced that the Falcon Heavy was certified after its maiden flight last year, allowing it to win contracts for launching the most critical operational satellite. The Air Force signed the contract for the STP-2 mission with SpaceX in December 2012 as a purely experimental mission.
Since the last milestone in certification, SpaceX has issued two launch orders for missions AFSPC-44 and AFSPC-52, to be launched by NASA's Kennedy Space Center in late 2020 and Early 2021.
The STP-2 mission is now the third certification flight for the Falcon Heavy as the Air Force prepares to entrust more important payloads to the launcher.
"What we do now is what we do Call the Spaceflight process," said Bongiovi.
"This launch, STP-2, is the third certification flight. It's one of many data and review kits we do with SpaceX and each contractor we certify for (and) do a one-time design and validation to get to the point where we (this) certify this launcher is ready to launch the critical national security payloads that we will use in these two missions. "
The Air Force will also use the experience gained from the STP-2 mission to certify re-used rocket hardware for national security missions. In the Airbus spacecraft launch so far, all newly built Falcon 9 boosters have been used.
"The launch was originally just an opportunity to characterize the launcher for future use by the National Security Space Launch Program, but now this is the first launch of the Air Force with previously flown rocket hardware. "Bongiovi said.
SpaceX has successfully rerun a Falcon booster 22 times since March 2017.
"The previously flown hardware is being used Providing critical insights into reusability and quality assurance that will enable us to make space access to the warfighter more cost effective and convenient, and I welcome the efforts of our industrial partner SpaceX to achieve this," said Bongiovi. 19659003] In the launch agreement for AFSPC-52 announced last year, the Air Force agreed to pay SpaceX $ 130 million for a Falcon Heavy mission. The Delta 4-Heavy rocket, the largest vehicle in the fleet of SpaceX competitor United Launch Alliance, is sold for about $ 300 million per flight.
When SpaceX convinces the Air Force to certify reused missiles for national security missions, this equates to the price of a hawk. A serious mission could continue to decline.
"The reason we are pleased about this and the hardware already installed (STP-2) is that we have been able to follow the recovery and renewal of these boosters.
"Over the last few years, we've been working hard on state mission assurance to make sure we've got the track record. We've had 76 consecutive successes, "said Bongiovi, referring to the National Air Force Security Division, formerly known as the EELV program, which primarily used the ULA Atlas and Delta rockets to set that record. "Sometimes it's better to go and do something than just write the procedures."
The STP-2 mission was originally supposed to be launched with brand-new boosters, but the Air Force and SpaceX agreed to change their plans late last year. STP-2 should be launched in Falcon Heavy's second mission, but the Contract change has pushed the launch of STP-2 behind the launch of the Arabsat 6A telecommunications satellite in the SpaceX queue According to Air Force officials, boosters from the Arabsat 6A mission are among the "softest" in SpaceX inventory. As they descended on Florida's space coast in April, they encountered relatively harmless aerodynamic forces and structural loads.
SpaceX's launch contract for the STP-2 mission had previously been estimated at $ 185 million, according to Lieutenant-Colonel Ryan Rose, head of small-launch and destination operations at Kirtland Air Force Base.
The launch cost the Luftwaffe now about 160 million dollars. A "big factor" in cutting costs was the military's agreement to fly the STP. 2 mission with reused rocket boosters, Bongiovi said.
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