SpaceX’s third Falcon Heavy rocket took off from the Kennedy Space Center LC-29A at 2:30 AM on Tuesday (2:30 PM GMT+8), delivering 24 satellites and weather observation spacecraft into orbit on a marathon three-and-a-half hours mission for the US Air Force.
The mission is said to be the most challenging mission ever performed by SpaceX, with four engine burns on the upper stage to deliver 24 payloads into their respective orbits. The mission included the successful landing of the Falcon Heavy’s two side boosters back at Cape Canaveral Landing Zone, and a SpaceX recovery boat named ‘Ms. Tree’ caught part of the rocket’s payload fairing that was jettisoned during launch for the first time after trying for more than a year.
SpaceX’s fairing recovery boat, recently renamed from “Mr. Steven” to “Ms. Tree,” is fitted with a giant net to catch the rocket’s fairing shell as it descends under a parafoil. The payload fairing protects satellites from aerodynamic friction during the first few minutes of launch, then jettisons in two halves in a clamshell-like fashion to lighten the rocket’s load once it has climbed into the rarefied upper atmosphere.
Since early 2018, SpaceX has tried using the fast-moving boat to steer underneath a fairing. But the efforts chalked up a series of near-misses, prompting engineers to evaluate reusing fairings that fell into the sea, which require more refurbishment after exposure to salt water.
But on Tuesday’s catch shows there is a promise for SpaceX’s preferred method of recovery.
SpaceX has outfitted its fairings with avionics, thrusters and steerable parachutes to make a soft landing. The company wants to reuse the fairing, eyeing it as the next step in reducing launch costs after proving the landing and reuse of Falcon booster stages.
Elon Musk, SpaceX’s founder and CEO, told reporters last year that the fairing costs around $6 million. Musk has identified the payload fairing as the next component that could be recovered and reused, following SpaceX’s pioneering achievement in landing and re-flying first stage boosters.
SpaceX eventually aims to catch both halves of the fairing.
However, the Falcon Heavy’s center core missed its target and crashed into the ocean upon landing. Elon Musk has said on his social media that they were expecting a 50% chance of the center core survivability when it enters the Earth’s atmosphere with four times the speed of a rifle bullet.
The primary mission was a success. The Air Force confirmed in a tweet on Tuesday afternoon that all of the payloads launched by the Falcon Heavy were alive and transmitting signals.
The Falcon Heavy’s three boosters drove the rocket off the pad with some 5.1 million pounds of thrust, more than any other launcher currently in service, and steered the vehicle toward the east.
Around two-and-a-half minutes into the launch, the side boosters shut down and separated from the Falcon Heavy’s center core to begin a series of propulsive maneuvers guiding the twin rockets back to Landing Zone 1 and Landing Zone 2 at Cape Canaveral Air Force Station, around 9 miles (15 kilometers) south of pad 39A.
Speeding back from the edge of space, the rockets reignited their engines for a re-entry braking burn, and a final maneuver to slow for nearly simultaneous landings at Cape Canaveral.
A pair of double sonic booms echoed across Florida’s Space Coast as the rockets returned.
Tuesday morning’s mission was the first time SpaceX has landed two rocket boosters at the same time at night. The side boosters both flew on the previous Falcon Heavy mission with the Arabsat 6A commercial communications satellite in April, when they also landed back at Cape Canaveral.
After release of the side boosters, the Falcon Heavy’s brand new center core throttled up its engines to full power. The core stage operated at partial power for the first couple of minutes of the mission to conserve fuel.
Around three-and-a-half minutes after liftoff, the core stage turned off its engines and separate to begin its own controlled descent to SpaceX’s offshore drone ship positioned nearly 770 miles (1,240 kilometers) east of Cape Canaveral.
Live video transmitted from the drone ship showed the core stage narrowly missed landing. The recovery vessel was parked farther downrange than for any previous SpaceX mission, and the Falcon Heavy’s core stage came down faster than any booster before.
The first burn heaved the mission’s 8,157-pound (3,700-kilogram) payload stack into low Earth orbit, where 13 spacecraft deployed from adapters on the Falcon Heavy’s upper stage.
The first orbital target for the STP-2 mission ranged in altitude between about 186 miles (300 kilometers) and 534 miles (860 kilometers). The first orbit had an inclination, or tilt, of 28.5 degrees to the equator.
The first of the payloads to release from the Falcon Heavy is Oculus-ASR, a microsatellite developed by students at Michigan Technological University in partnership with the Air Force 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. It will also release a pair of small spherical masses to help calibrate instruments that track orbiting space objects.
Twelve CubeSats also ejected from carrier modules on the upper stage.
The Naval Research Laboratory’s Tether Electrodynamics Propulsion CubeSat Experiment, or TEPCE, mission consists of two CubeSats that will be connected by a nearly 3,300-foot (1-kilometer) electrically conducting tether. The experiment will test the tether’s ability to provide electrodynamic propulsion in space, which future missions could use in place of conventional rocket fuel.
The FalconSat 7 satellite, a toaster oven-sized CubeSat developed at the U.S. Air Force Academy, next deployed from the rocket. FalconSat 7 will test a deployable optical solar telescope structure in orbit, a device that could be used on future military reconnaissance and surveillance missions.
The Falcon Heavy then released the ARMADILLO CubeSat developed at the University of Texas at Austin. ARMADILLO carries a dust detector to characterize the population of tiny space debris objects in low Earth orbit.
The U.S. Naval Academy’s PSAT 2 and BRICSAT 2 CubeSats, each carrying amateur radio payloads, then separated form the rocket. Then the rocket deployed a Prometheus CubeSat for U.S. Special Operations Command.
NASA’s two Enhanced Tandem Beacon Experiment, or E-TBEx, CubeSats were next to separate from the rocket. The CubeSats will transmit radio signals down to receiving stations on Earth for scientists to examine how the transmissions are perturbed by disturbances in the ionosphere, a layer in the upper atmosphere through which GPS navigation and satellite communication signals must traverse to reach users on the ground.
The final satellites to separate in the STP-2 mission’s first orbit were the Launch Environment Observer and StangSat CubeSats, which recorded telemetry and environmental data inside their deployer box during launch. The LEO CubeSat was built by students at Cal Poly, and StangSat comes from students at Merritt Island High School in Florida.
With the first batch of satellites away, a second firing by the Falcon Heavy’s upper stage engine propelled the rocket into a circular orbit around 447 miles (720 kilometers) above Earth, with an inclination at 24 degrees, closer to the equator.
Georgia Tech’s suitcase-sized Prox-1 microsatellite was the first spacecraft to deploy in the STP-2 mission’s second orbit. Prox-1, also funded through an Air Force Research Laboratory grant, will test proximity operations and in-orbit inspection techniques after releasing a daughter satellite July 1 named LightSail 2, a crowd-funded CubeSat from the Planetary Society designed to demonstrate the propulsion capability of a solar sail, which harnesses pressure from sunlight for thrust.
A satellite named NPSAT 1 developed at the Naval Postgraduate School next separated from the Falcon Heavy. NPSAT 1 carries two instruments from the Naval Research Laboratory to measure electron cloud densities in Earth’s ionosphere, a layer high above Earth that affects long-range radio communications. Engineers will also use the microsatellite to test a radiation-tolerant computer processor, experimental solar cells, and low-cost memory devices, rate sensors and a commercial digital camera.
The next event was the deployment of the Orbital Test Bed spacecraft built by General Atomics. The Orbital Test Bed, or OTB, mission hosts several payloads, including the Deep Space Atomic Clock experiment from NASA, which will test a new type of hyper-accurate atomic clock that could make it easier for deep space probes to navigate.
Another package attached to the OTB satellite carries the cremated remains of 152 people, including the late astronaut Bill Pogue and space journalist and historian Frank Sietzen. The payload, called “Heritage Flight” and arranged by Celestis, will remain in orbit with the OTB spaceraft for around 25 years.
NASA’s Green Propellant Infusion Mission also separated in the 447-mile-high orbit. Built by Ball Aerospace with a propulsion system from Aerojet Rocketdyne, the mission will test a new type of non-toxic “green” propellant that could be used on future satellites to replace hydrazine, a caustic fuel commonly used on spacecraft because it can be stored for years at room temperature.
The Falcon Heavy upper stage then maneuvered into the proper orientation for separation of six identical satellites for the Constellation Observing System for Meteorology, Ionosphere, and Climate-2, or COSMIC-2, mission.
The COSMIC-2 satellites, each about the size of a standard kitchen oven, will form a weather observation network collecting data on temperature, pressure, density and water vapor at various layers in Earth’s atmosphere. The COSMIC-2 mission was developed by an international consortium of institutions led by NOAA, the U.S. government’s weather agency, and Taiwan’s National Space Organization, with instrument contributions from the Air Force.
Telemetry data radioed from the Falcon Heavy rocket confirmed all six COSMIC-2 satellites separated as planned, setting the stage for the final phase of the STP-2 mission.
The rocket’s Merlin upper stage engine reignited two more times to target a unique orbit between 3,728 miles (6,000 kilometers) and 7,456 miles (12,000 kilometers) in altitude, with an inclination of 42 degrees to the equator.
The fourth burn set a record for a SpaceX mission. No previous Falcon 9 or Falcon Heavy launch had fired its upper stage engine more than three times.
At 6:04 a.m. EDT (1004 GMT), more than three-and-a-half hours after liftoff, the Falcon Heavy deployed the mission’s final payload — the Air Force Research Laboratory’s Demonstration and Science Experiments, or DSX, spacecraft.
The DSX satellite will fly in a slot region between the Van Allen radiation belts with instruments 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.
STP-2 mission is a test for the US Air Force to certified Falcon Heavy for heavy lift operation involving the US Military payloads. The Air Force will also use the experience gained from the STP-2 mission to help certify reused rocket hardware for national security missions.