After more than a decade of planning and preparation, excitement, and frustration, NASA is ready to launch the first human-capable vehicle for Beyond Earth Orbit (BEO) exploration in more than four decades on Thursday, 4 December. Liftoff of the inaugural Orion spacecraft on the long-awaited Exploration Flight Test (EFT)-1 is targeted to occur from Space Launch Complex (SLC)-37B at Cape Canaveral Air Force Station, Fla., at 7:05 a.m. EST. The “launch window” extends for two hours and 39 minutes and, according to Patrick Air Force Base meteorologists, the weather forecast currently predicts partly cloudy skies, with a 20 percent likelihood of rain and a 10 percent probability of lightning. As described in yesterday’s AmericaSpace EFT-1 preview article, the mission will be boosted aloft by the most powerful rocket currently in active operational service, anywhere in the world—United Launch Alliance’s (ULA) Delta IV Heavy—which is tasked with delivering the spacecraft to a peak altitude of 3,600 miles (5,800 km). Orion will then complete two orbits in 4.5 hours, before plunging back to Earth in excess of 20,000 mph (32,000 km/h) to test the hardiness of its heat shield at near-lunar-return velocities and temperatures of close to 2,200 degrees Celsius (4,000 degrees Fahrenheit).
Loading of liquid oxygen and hydrogen propellants into the Delta IV Heavy’s trio of Common Booster Cores (CBCs) early on the morning of Launch Day will begin at T-4 hours and 35 minutes. During this period, the NASA team in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, will take over control of the flight from the launch control team. Flight Director Mike Sarafin will head a 14-member team, which includes the positions of flight dynamics officer, electrical power system officer, emergency, environmental and consumables (EECOM) manager, command and data-handling officer, propulsion officer, guidance, navigation and control officer, guidance officer, instrumentation and communications officer, ground control officer, weather officer, and landing support officer. Their deliberations will be punctuated, just under two hours before T-0, by a briefing from the National Oceanic and Atmospheric Administration (NOAA) Spaceflight Meteorology Group about weather conditions at Orion’s primary recovery location in the Pacific Ocean, off the coast of Baja California. Alongside this report, the 45th Space Wing at the Cape will provide its own update on weather conditions for launch.
The Delta IV Heavy will enter its final pre-planned hold at T-4 minutes, which it should reach at about 6:46 a.m. EST. It will remain in the hold for about 15 minutes, during which time the final polls for launch will be performed by Sarafin’s team at JSC. They will issue their “Go-No Go” consensus to the Mission Management Team (MMT), which is based at Cape Canaveral Air Force Station and is chaired by Lockheed Martin’s Mission Manager, former shuttle flight director Bryan Austin. Shortly afterwards, at 6:57 a.m., the Orion spacecraft will transition to internal batteries and external power utilities from SLC-37B will be disconnected. Assuming that none of the Go-No Go polls produce anything untoward, the clock will be released from its hold at T-4 minutes at 7:01 a.m. and will resume counting into the Terminal Countdown.
Ignition of the three RS-68 engines of the Delta IV Heavy will occur at T-5 seconds, enabling each to ramp up to its maximum 705,900 pounds (320,200 kg) of thrust. After telemetry data confirms that the start-up sequence is satisfactory and within required parameters, the liftoff command will be issued and the stack will depart SLC-37B at 7:05 a.m. EST. As seen during previous Heavy launches, the enormous amount of hydrogen being dumped through the engines to condition them, ahead of the opening of liquid oxygen valves and the onset of the ignition sequence, generates a huge ball of fire which dramatically blackens the insulation of the core and strap-on boosters. “During climb-out, free hydrogen continues to attach itself to the base of the vehicle,” explained an Aviation Week article, quoted by CollectSpace.com, “where it burns on insulation designed for that purpose. While the fire is inconsequential, parts of the boattail remain ablaze until ascent into thinner air.”
Seconds after clearing the SLC-37B tower, the Heavy will execute a computer-commanded pitch, yaw, and roll program maneuver. Pitch and yaw controllability is effected by gimballing the engines themselves, whilst roll is accomplished by vectoring the turbine exhaust gases of the RS-68s. This will actively guide the stack onto its proper heading and flight azimuth to deliver Orion into low-Earth orbit. Fifty seconds into the ascent, the core CBC will throttle back to about 57 percent of rated performance, in order to conserve its propellant. The stack will pass through a region of maximum aerodynamic turbulence upon its airframe, colloquially known as “Max Q,” at T+83 seconds and will hit Mach 1 shortly thereafter at T+85 seconds.
By three minutes and 50 seconds after leaving Cape Canaveral Air Force Station, the thrust of the two strap-on CBCs will also be reduced to 57 percent, and they will shut down and separate from the rapidly ascending vehicle about seven seconds later. By running at 57 percent for the early phase of the journey uphill, the core will therefore have sufficient remaining propellant to support its own flight after the departure of the boosters. At T+246 seconds, its RS-68 will throttle back up to 100-percent performance and will burn for another 80 seconds, shutting down at T+330 seconds—some 5.5 minutes into the flight—and separating soon afterwards.
The turn will then come for first of two “burns” by the restartable Delta Cryogenic Second Stage (DCSS) second stage and its single oxygen/hydrogen-fueled RL-10B2 engine, capable of 24,750 pounds (11,225 kg) of propulsive yield. This is due to ignite about five minutes and 49 seconds after liftoff and will burn for almost 12 minutes, its specific impulse enhanced by means of an electrically-driven extendable carbon-carbon nozzle. The DCSS also houses the Delta IV Heavy’s avionics, navigation, telemetry, and communications systems, and can remain “active” for more than seven hours during extended-duration mission profiles. It can also execute Contamination and Collision Avoidance Maneuvers after the departure of its primary payload.
During the course of the initial DCSS burn, the three protective fairing panels—each measuring 13 x 14 feet (3.9 x 4.3 meters)—will be jettisoned from Orion’s Service Module and the now-unneeded LAS will also be discarded. At 7:22 a.m. EST, some 17 minutes and 40 seconds after departing the Cape, the RL-10B2 engine will fall silent, having established the EFT-1 spacecraft into an initial orbit of 115 x 552 miles (185 x 888 km), inclined 28.8 degrees to the equator. The stack will then drift for a further 98 minutes, or slightly more than one full orbit of Earth, before the DCSS ignites a second time for the lengthy “Big Burn” to boost Orion to an altitude of 3,600 miles (5,800 km) and a location 15 times further into space than the International Space Station (ISS). This makes EFT-1 very similar in profile to the planned, but unrealized Apollo “E” mission.
Scheduled to get underway at one hour, 55 minutes, and 26 seconds into the mission, this second burn will run for four minutes and 45 seconds, concluding at 9:05 a.m. Five minutes after the DCSS shuts down for the second and final time, Orion will enter its First High Radiation Period, passing into the lower Van Allen Belt, during which time its cameras will be temporarily deactivated to avoid damage. The spacecraft will rise above this particularly intense radiation neighborhood by 9:25 a.m., after which its cameras will be switched back on, and, shortly afterwards, its Reaction Control System (RCS) will be powered up. Orion is expected to reach a peak altitude of 3,609 miles (5,808 km) at 10:10 a.m.—approximately three hours and five minutes into the mission—which will place a human-capable vehicle further from the Home Planet for the first time since December 1972. At this altitude, the camera-returned view of Earth should be spectacular, filling 60 percent of Orion’s windows and resembling a six-foot-wide (1.8-meter) disk, held at arm’s length.
Hitting the peak of its high-apogee orbit, Orion’s Crew Module will separate from the DCSS/Service Module stack at 10:28:41 a.m. This will permit the Crew Module to begin its hazardous descent back through the “sensible” atmosphere and accomplish a splashdown in the Pacific Ocean. In addition to the blistering velocity of 20,000 mph (32,000 km/h), the spacecraft will be required to endure its Second High Radiation Period through the lower Van Allen Belt as it plunges back to Earth. Again, its cameras will be temporarily shut down to survive the passage. At 11:02:11 a.m., a little less than four hours since liftoff, the Crew Module’s RCS thrusters will ignite for 10 seconds to begin the process of entering the upper atmosphere. This will mark the fastest re-entry by a human-capable vehicle since the closure of the Apollo era.
Orion will emerge from its second passage through the lower Van Allen Belt at 11:10 a.m. and about eight minutes later the spacecraft will hit “Entry Interface” at an altitude of 400,000 feet (75 miles or 122 km), during which time it will endure temperatures as high as 2,200 degrees Celsius (4,000 degrees Fahrenheit) on its airframe. This temperature is about 80 percent as hot as Orion would experience during a return from lunar distance and is expected to represent the most challenging test of the capabilities of its heat shield currently possible. At 11:18:41 a.m., shortly after Entry Interface, the superheated plasma around the Crew Module is expected to block out communications for about 150 seconds.
Maximum re-entry heating should be reached a couple of minutes later and after passage through the worst of this furnace Orion’s Forward Bay Cover will be jettisoned at 11:24:29 a.m., to expose its parachutes. Two drogues will be deployed at an altitude of 22,000 feet (6,700 meters) and a velocity of 300 mph (480 km/h), helping to slow the Crew Module down to around 100 mph (160 km/h). Ninety seconds later, at 11:25:40 a.m., three pilot chutes will be used to pull out Orion’s trio of massive main canopies at an altitude of 6,500 feet (2,000 meters). Covering the area of a football field when deployed, the main parachutes will unfurl in a “staged” fashion, firstly to 3-percent-open, then 10-percent-open, and eventually to full-open. This technique has been developed to keep the aerodynamic forces on the canopies to a minimum, providing for a softer descent and ensuring the safety of the hardware. Even if one parachute fails, the system has the capability to slow the 19,000-pound (8,600 kg) Crew Module to a soft splashdown at just 17 mph (27 km/h).
Current projections anticipate that the EFT-1 mission will end in the Pacific Ocean, about 600 miles (965 km) off the coast of Baja California, far to the southwest of San Diego. Assuming an on-time launch, splashdown should occur at 8:28:29 a.m. PST (11:28:29 a.m. EST), concluding a mission of four hours, 23 minutes, and 29 seconds and two orbits of Earth. Putting Orion’s high-speed return into perspective, the period from Entry Interface to hitting the ocean will take a mere 11 minutes, as opposed to around 40 minutes during the 17,500 mph (28,200 km/h) shuttle re-entry profiles.
The spacecraft’s uprighting system will inflate to achieve a heads-up orientation, and it will remain powered-up after hitting the waters of the ocean. The retrieval effort will require the combined efforts of a joint NASA-Navy team. Orion Lead Flight Director Mike Sarafin will contact Recovery Director Jeremy Graeber, aboard the amphibious recovery vessel USS Anchorage, to advise him of the spacecraft’s overall health and status after a journey of more than 60,000 miles (96,600 km). Also supporting the EFT-1 landing will be the Navy’s salvage ship, USNS Salvor. Small Zodiac boats will be deployed to attach a sea anchor, load-distributing collar, and tether lines, after which they will begin towing operations into the Anchorage’s well deck. “The Crew Module will be winched into the flooded well deck and placed on rubber shock absorbers,” noted NASA’s EFT-1 press kit. “Water will be drained from the well deck, leaving Orion secure and dry. Once the ship starts the journey back to shore and reaches calm waters, the Crew Module then will be placed into its recovery cradle and readied for offloading.”
Meanwhile, the Salvor’s cranes will lift the Forward Bay Cover and parachutes from the ocean onto the deck, and all hardware will be transported to a pier at the U.S. Naval Base San Diego. The Crew Module will later be driven by truck to the Kennedy Space Center (KSC), Fla., where it will be refurbished and used in Orion’s Ascent Abort-2 (AA-2) test, currently scheduled to occur from the Cape’s Space Launch Complex (SLC)-46 in 2019.
Next weekend’s history articles will focus on history “In the Making”, reflecting on the 42nd anniversary of Apollo 17 and the maiden voyage of Orion as a new era in humanity’s exploration of deep space begins.
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