Space Launch Complex Six (SLC-6) at Vandenberg AFB, CA., is the West Coast launch site for the Space Transportation System (Shuttle). Construction of the launch facility is finished, ground support equipment has been installed, and facility verification testing with the non-flying vehicle Enterprise is complete. All launch systems and procedures will be thoroughly checked at and ready to support launch activities this year even though the first launch is scheduled for March 20,1986.
The launch facility, originally built for the Manned Orbiting
Laboratory program (MOL), was “Mothballed” in 1969. It consisted
of a Mobile Service Tower, a concrete launch pad, a flame duct and a Launch
In April 1971, a Shuttle Launch and Recovery Board was formed to review possible launch and recovery sites a Space Transportation System. Vandenberg was selected as a launch site, along with NASA's Kennedy Space Center
(KSC) in Florida. A logical choice, Vandenberg can provide near-polar and retrograde azimuth launches that cannot be achieved efficiently a safely from Kennedy.
A special task force established in 1974 evaluated three possible launch sites at Vandenberg. Cost analysis demonstrated a 100 million plus cost savings using the existing MOL site (SLC-6) over building a new facility. The SLC-6 option was approved in 1975 and construction began in 1979.
Using existing facilities requires Shuttle operations to be conducted
at several Vandenberg locations. The Runway, Orbiter Maintenance
and Checkout facility, the Orbiter Lifting facility, the Thermal Protection
Facility, supply warehouses and a majority of support personnel are located
a North Vandenberg; while SLC-6, which includes the Launch Control Center,
Payload Preparation Room, Payload Changeout Room, Shuttle Assembly Building,
Access Tower, Launch Mount, Mobile Service Tower and the three exhaust
ducts, is located on South Vandenberg.
Also located a South Vandenberg is the Solid Rocket Booster Refurbishment and Subassembly Facility, the External Tank Checkout and Storage facility and a harbor where external tanks are received.
North Vandenberg AFB Operations
The first three missions begin when the orbiter, already prepared for flight at KSC, is delivered to the airfield by 747 Shuttle Carrier Aircraft (SCA). The Air Force and contractor ground support team will lift the orbiter off the SCA using the Orbiter Lifting Facility adjacent to the airstrip. After early 1987, operations begin with a normal non-powered landing. The former 8,000-foot runway has been strengthened and extended to 15,000 feet with a 1,000-foot overrun at each end.
After arriving, the orbiter is towed to the Orbiter Maintenance
and Checkout Facility (OMCF) for necessary maintenance and payload and
orbiter safing and deservicing. The OMCF is functionally comprised of a
high bay hangar-type area, a payload area with two large cells and a administrative
area. It also provides the means to install payloads that require
horizontal emplacement before a mission. The OMCP features several
layers of work platforms and a clean room environment for payload, cargo
bay and crew cabin activities. The orbital
maneuvering system (OMS) pods and forward reaction control system are shipped to KSC for servicing as required.
The orbiter will be carried atop a special 76-wheel transporter to the launch pad on South Vandenberg over 17 miles of existing base and public roadways. Nearly two miles of this route have been modified to accommodate the orbiter, which requires a two-fat wingtip clearance (78-foot wingspan) and turns with a minimum radius of 162 feet. Rocky hillsides have been excavated, new road segments bypass sharp intersections, and security guard stations have been placed on wheels, to clear the road when the orbiter is taken to SLC-6.
South Vandenberg Shuttle Operations
The Vandenberg approach to vehicle assembly differs from KSC procedures. There, components (orbiter external tank, and solid rocket boosters) are assembled on a mobile launch platform inside the Vehicle Assembly Building and moved to the launch area rather than the "integrate-on-pad" concept used here. Given Vandenberg's terrain and existing facilities, this is the only practical approach.
The integrate-on-pad concept means components of the Space Shuttle vehicle are brought piece by piece to SLC-6 and assembled on the stationary launch mount. Two huge mobile structures join to enclose the mount, providing a protective shelter during assembly. The two buildings remain in their protective positions until the launch countdown cues them to move to their prelaunch positions. Also a majority of the payloads are installed as the Shuttle rests on the launch mount, using another mobile structure.
New launch pad construction began in 1979 when the existing Mobile Service Tower (MST) was moved 150 feet from its mothballed site. Modifications included replacing the overhead 50-ton crane with a 200-ton crane and shortening the structure 40 feet. Service platforms conforming to the shape of Shuttle components were added.
The Shuttle Assembly Building (SAB) was added to the SLC-6 plan
in 1981. It provides additional lifting capacity and weather protection.
It is a large empty shell with a huge garage-like door at one end and a
125-ton overhead crane.
The MST and the SAB move toward each other on railroad-like tracks from their parked positions and mate around the launch mount. Together their overhead cranes lift and assemble the Space Shuttle vehicle. The assembly begins as the solid rocket boosters (SRBs) are stacked on the launch mount. Next, the two cranes, one located in the top of the MST and the other in the SAB raise the external tank and position it vertically between the boosters with less than a quarter inch clearance on each side. The same cranes lift the orbiter vertically beside the external tank. Before launch, the MST and the SAB roll back to their "parked for launch" positions approximately 375 feet and 285 feet, respectively, from the launch mount. Hydraulic jacks raise the buildings on and off their tiedowns. Travelling drive systems move the buildings at speeds up to 40 feet per minute. Movement of the MST and SAB takes 50 to 40 minutes including unlocking the tiedowns, travelling and relocking.
Solid rocket motor segments are shipped has by rail from the manufacturer in Utah, and stored in the solid rocket booster facility. The facility has the capacity to store two complete flight sets -- 16 segments and related hardware. There the solid propellant is inspected for damage and final flight preparations are made with all the SRB components. The motor segments are then transported to the pad individually and stacked by the MST's overhead crane. The two boosters contain four segments each with special flight hardware attached to the top and bottom segments. They are 149 feet high, 12 feet in diameter and weigh approximately 1.3 million pounds each. Together at liftoff, they generate nearly 5.2 million pounds of thrust.
External tanks arrive here by ocean barge from the manufacturer in Louisiana across the Gulf of Mexico and through the Panama Canal to the south base harbor. Part of a 1930's-era Coast Guard lifeboat station, deactivated in 1952, it was modified to receive the 154-foot log, 27.8-foot diameter external tanks. Each 69,000 pound tank is off-loaded and towed to the external tank facility near the pad. It is stored there, inspected and shipped with the range safety system before being transported to the pad. Five external tanks can be housed in the facility, Four in storage and one in the checkout cell.
The launch mount is a steel-framed support structure anchored to the
center of the pad with openings into the flame ducts. It supports
the Space Shuttle vehicle for launch and provides ducting for the exhaust.
To supplement old MOL flame duct, 87,000 cubic yards of concrete were used
to build two additional ducts, each 50 by 70 feet, with walls 9 to 12 feet
thick, enough concrete to build a three-foot wide, four-inch thick sidewalk
from Los Angeles to San Francisco.
At liftoff, the exhaust from the solid rocket boosters and the Shuttle's main engines is channeled underground, exiting through the three ducts at the sides of the pad. Water flows into a deluge nozzle system into the launch mount to suppress acoustic energy that could damage the vehicle during liftoff. This sound suppression water system releases 760,000 gallons onto the pad and into the exhaust ducts in less than 50 seconds. A 375,000-gallon water tank, on a hill behind the MST, connected to a 1.25 million-gallon water tank, supplies
the gravity-fed system.
The Payload Preparation Room (PPR) at the west end of the pad is used
to prepare payloads and erect them for transfer to the orbiter via the
mobile Payload Changeout Room (PCR). The two "rooms" are actually
large buildings with matching payload doors. During payload transfer
operations, doors on both buildings are opened after an airtight seal is
established around the passageway to ensure cleanliness.
The payload is transferred from the PPR to the PCR by a special overhead handling system that moves from one building to the other on connecting tracks.
The PCR rolls 750 feet through the SAB to the launch mount and mates with the upright orbiter. Six sliding doors on the west side of the SAB open to permit the PCR to roll into the building, mate and install payloads into the orbiter's 60-by-f5-foot cargo bay.
The Access Tower is a steel-framed structure located beside the launch mount. This structure allows crew access to the orbiter flight deck and provides slide-wire escape baskets to be used in an emergency. It also features gaseous hydrogen and oxygen vent arm, a high-speed elevator and a clean room.
The orbiter, 122 feet long and 78 feet wide, is about the size
of a DC-9 aircraft. The cargo bay can accommodate a full size commercial
bus and is capable of lifting a 32,000-pound payload on a Vandenberg launch,
about half that of a KSC launch. East Coast launches take advantage
of the earth's rotation (approximately 900 mph at the Cape) enabling them
to carry the additional weight. The orbiter weighs approximately 150,000
pounds empty and 185,000 pounds fully loaded.
Total fueled weight of the Space Shuttle vehicle is about 4.4 million pounds. The shuttle's three main engines and two solid rocket boosters generate a sea
level thrust of approximately 6.3 million pounds at liftoff.
Requirements for preparing Vandenberg facilities for the Space Transportation System project included about 250,000 cubic yards of concrete, the equivalent of a 25 mile, four-lane interstate, 9,000 tom of reinforcing steel and 15,000 tons of structural steel.
Current plans call for an average of four yearly launches beginning with the first operational flight from America's Western Spaceport now scheduled for late
March 1986. Eventually the Vandenberg facilities could accomodate as many as 10 launches per year.
Read more about the SLC-6 and its curse by Roger Guillemette Click Here