Screenshot from ULA Webcast of the launch of MMS. Oh starry night. The lights are bright tonight
Mission Rundown: ULA - Atlas V 421 - MMS
Written: January 13, 2023
Pack. Stack. And send them
United Launch Alliance’s Atlas V rocket launched NASA’s Magnetospheric Multiscale (MMS) mission on Thursday.
Launching from Space Launch Complex 41 on Cape Canaveral Air Force Base, the rocket placed the four-satellite constellation into a highly elliptical orbit, beginning a two-year mission to study reconnection in the magnetosphere.
The Space Launch Complex 41 has been earmarked for future use by manned missions to the International Space Station using Boeing’s CST-100 spacecraft launched atop an Atlas, with construction work on a new crew access tower beginning last month.
Notam on debris areas from Atlas V 421. Core booster crashes 2800 km downrange ±100 km
The launch from SLC-41 occurred at the start of a thirty-minute window on Thursday March 12, 2015 at 22:44 EDT - March 13, 2015 at 02:44 UTC on Friday.
The MMS Payload
The Magnetic Multiscale – or MMS – mission consists of four identical spacecraft which will be used to conduct plasma physics research in the environment of the Earth’s magnetosphere. The mission is intended to help scientists better understand a phenomenon called magnetic reconnection which has been observed in plasmas.
MMS getting ready to be enclosed in the fairing. It's kind of a big stack satellites
The MMS satellites were constructed by NASA’s Goddard Space Flight Center (GSFC) using a custom-made bus.
NASA graphic image. The satellite BUS with seven Solar Arrays removed for visual effect
Flying in a tetrahedral formation, the MMS spacecraft will fly through the heart of reconnection events to allow three-dimensional mapping of how the particles and fields at hand interact.
Octagonal in shape, the satellites measure 1.666 meters (5.476 feet) across by 1.230 meters (4.033 feet) high. Stacked together at launch, the combined spacecraft measure 4.920 meters (16.14 feet) in height.
During construction parts of the internal structures of the spacecraft were anodised different colors to help engineers distinguish them. Spacecraft number one was coloured orange, number two was coloured blue, number three green and number four pink.
The colors reportedly were intended to reflect the colors of the uniforms worn by The Beatles on the cover of their album Sgt. Pepper’s Lonely Hearts Club Band, as the spacecraft had been unofficially named John, Paul, George and Ringo after the members of the 1960s rock quartet.
Bound for highly elliptical orbits of 2,500 by 70,080 kilometers (1,600 by 43,500 miles, 1,300 by 37,840 nautical miles), following on-orbit commissioning the satellites will spend eighteen months studying reconnection events on the dayside boundary of the magnetosphere, where the magnetic fields of the Earth and Sun interact.
Following this the mission will enter a second phase with the spacecraft raising their apogees to 153,000 kilometers (95,000 miles or 82,600 nautical miles) in order to fly through the Earth’s magnetospheric tail and study events on the night side of the planet.
Each of the four spacecraft carries three suites of instruments for a total of eleven experiments, with an identical loadout on all four vehicles.
The Hot Plasma Suite, designed to characterize the plasma environment in which reconnection events occur, consists of the Fast Plasma Investigation (FPI) and Hot Plasma Composition Analyzer (HPCA).
The Energetic Particles Detector Suite, or EPD, is the second suite of instruments present aboard MMS and is intended to study the excitation of particles to extremely high energy levels as the result of magnetic reconnection.
Consisting of the Fly’s Eye Energetic Particle Sensor (FEEPS) and Energetic Ion Spectrometer (EIS), the EPD Suite will be used to test physicists’ theories about this excitation and whether it applies to particles heavier than electrons.
The final part of the MMS payload, the Fields Suite, consists of six instruments to conduct three-dimensional monitoring of the Earth’s magnetic field with a time resolution of up to one millisecond, integrated through the FIELDS Central Electronics data collection system.
The six instruments are the Analogue Fluxgate magnetometers, the Digital Fluxgate magnetometers, the Search Coil Magnetometer, The two Electron Drift Instruments equipped with electron guns and detectors and the Spin-Plane Double Probe.
A pair of Active Spacecraft Potential Control Devices (ASPOCs) are fitted to each of the satellites to reduce or cancel out the vehicles’ own electrical fields, which could otherwise affect observations and result in spurious data or experimental errors.
The Atlas V 421 launch
Thursday’s launch took place from the East-coast home of the Atlas V rocket, Space Launch Complex 41 - SLC-41 at the Cape Canaveral Air Force Station.
The deployment of MMS was the forty-third Atlas launch from Space Launch Complex 41 and the seventieth from the pad overall.
The MMS launch began with ignition of the Atlas’ RD-180 main engine, at the 2.7-second mark before liftoff. This was followed by solid rocket motor ignition and liftoff at around T+1.1 seconds, when the thrust generated by the engines exceeded the weight of the loaded vehicle.
Climbing away from its launch pad, AV-053 executed a series of pitch and yaw maneuvers to establish its launch trajectory beginning 5.9 seconds into the mission. The vehicle headed East downrange over the Atlantic Ocean on an azimuth of 99.0 degrees.
As it accelerated through the atmosphere the Atlas reached a speed of Mach 1 48.9 seconds after liftoff, passing through the area of maximum dynamic pressure 13.6 seconds later.
The first major milestone in the mission was the separation of the two solid rocket motors at two minutes and 18.6 seconds elapsed time, the boosters having burned out approximately forty seconds previously.
First stage flight concluded with Booster Engine Cutoff (BECO), four minutes and 9.7 seconds after launch, with the RD-180 shutting down as it approached propellant exhaustion. Stage separation occurred six seconds after cutoff, with the RL10 beginning its pre-start sequence.
Centaur ignition took place ten seconds after staging, commencing the first of two planned burns for the second stage.
This first burn lasted nine minutes and 3.3 seconds, placing the Centaur and its cargo into a parking orbit. About eight seconds into the burn the Atlas V’s payload fairing separated from around the MMS spacecraft at the nose of the rocket.
The burn was followed by a fifty-nine minute and 0.8 second coast phase before the RL10 restarted for its second and final burn of the mission.
This five-minute, 41.5-second burn established the initial deployment orbit for the MMS spacecraft, which separated at five minute intervals beginning fourteen minutes after the end of the final burn.
The target orbit for Thursday’s mission was an elliptical trajectory with a perigee of 585 kilometers (364 miles, 316 nautical miles), an apogee of 70,165 km (43,598 mi, 37,886 nautical miles), at an inclination of 28.77 degrees. From there the spacecraft will raise themselves into their operational orbits.
The Atlas V 421 rocket
NASA selected United Launch Alliance to deploy the MMS mission, making use of an Atlas V rocket in the 421 configuration. Designated AV-053, the Atlas consists of a Common Core Booster (CCB) first stage augmented by two solid rocket motors.
Atlas V 421 split in its major parts. Known points of data is listed in the graphic illustration
A single-engine Centaur upper stage sits atop the CCB, with the satellites encapsulated within a four meter (13-foot) payload fairing.
Measuring four meters in diameter, the fairing is available in three different lengths; a Large Payload Fairing (LPF) is 12.2 meters (40 ft) long, with the Extended Payload Fairing (EPF) and Extra-Extended Payload Fairing (XEPF) adding one and two extra 90-centimeter (2.95-foot) sections respectively.
For Thursday’s flight, the Extra-Extended fairing was used.
The first stage of the Atlas burns RP-1 propellant, oxidized by liquid oxygen. The Russian built RD-180 engine propels the stage, while two Aerojet AJ-60A solid rocket motors provide additional thrust during the earliest stages of the flight.
The Centaur is powered by a single RL10 engine which burns liquid hydrogen and liquid oxygen. For the MMS mission the Centaur will be sporting the older RL10A-4-2 engine which was used for the rocket’s first fifty flights before being replaced by the Delta IV-derived RL10C-1 on the most recent two launches.
Facts on the Atlas V 421 launch vehicle
Height of Atlas V 421: 59.1 meter - 194 feet
Mass at liftoff: 430,629 kg - 947,384 pounds
Thrust at liftoff: 7.1 mega-Newtons - 1.6 million lbf
Fuel onboard: 91,000 gallons of liquid propellant
LOX+LH2 = 66,000 gallon of cryogenic liquid propellant in three tanks
Core stage Atlas: 25,000 gallon RP-1 - 48,800 gallon LOX
Core stage weighs fully fueled 306,271.7 kilograms - 675,213.5 pounds
Core stage measures 35.63 meters - 116,9 feet tall and 3.81 meters - 12,5 feet wide
Core stage RD-180 main engine produces 3,826.9 kiloNewtons - 860,321.35 pounds of thrust at sea level while the thrust level increases to 933,406.73 pounds in space
Upper Stage Centaur: 13,050 gallon LH2 - 4,150 gallon LOX
Upper Stage Centaur weighs fully fueled 23,073 kilograms - 50,867.3 pounds
Upper Stage Centaur measures 12.68 meters - 41,6 feet tall - 3.05 meters - 10 feet wide
RL-10A-4-2 engine is optimized for vacuum usage with an extended big nozzle - engine bell, so it only produces 99.1 kilonewtons - 22,300 pounds in space
Centaur has 150 kg (340 lb) of Hydrazine - N2H4 is stored in a tank
Centaur has Helium - He pressure vessel storage tanks: Unknown so far
Two AJ-60A SRB’s weighs 93,358 kilo - 205,898 pounds
Two AJ-60A SRB’s produces 3,336.8 kiloNewton - 759,200 lbf of thrust
SRB’s measures 17 meter - 55.75 feet in height and 1.6 meter - 5.17 feet in diameter
Atlas V 401 XEPF 4.2 meter fairings weigh 2,487.0 kilograms - 5,482.9 pounds
Atlas V 401 XEPF Payload Fairing measures 14.0 meter - 46 feet in length ‘45.3 feet’
MMS payload weighs 5 440 kg ~ 11 968 pounds
A: Geosynchronous Transfer Orbit - 3,243 x 22,000 miles (834 x 35,739 km x 18.9 deg)
Flight plan A includes a 58 second deorbit burn. Centaur second stage is scuttled.
B: Geosynchronous Transfer Orbit - 3,243 x 22,000 miles (5,218 x 35,500 km x 17.6 deg)
Flight plan B includes a 58 second perigee raise burn. Centaur is derelict space debris.
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