The Space Transport System was built to give ubiquitous access to low Earth orbit. It was meant to be a utility truck that flew 40-50 missions a year. Somewhere along the line, the reality of budget limitations, politics, and laws of science intersected to give a program that only once reached an all time high rate of 10 missions a year. However, at the end of 30 years of operations, the STS program had accomplished a spectacular number of feats such as having successfully journeyed 133 times into Space, carried 355 individual astronauts aboard the 5 orbiters, deployed many satellites, Hubble, Chandra and helped build a new Space Station. Even her detractors had to admit to the utility of the feats performed by the STS program and the engineering accomplishments embodied by the program.
While millions of people around the globe have witnessed the spectacle of the 17,500+ miles per hour orbiters at 150 miles + altitude or an orbiter climbing gracefully atop a fiery long flame and white smoke trail on launch day, very few have actually been inside. This number is further reduced when it is a powered orbiter. This is unfortunate as to truly appreciate the engineering marvel that a space shuttle orbiter is, one must see her come alive on the flight deck just as the astronauts would see her in orbit. A “live” orbiter is a sight that even astronauts admit relegates their training mockups and simulators (which they spend all their terrestrial training time on) to a lower place on their scale of cool experiences.
My journey to the flight deck of “Atlantis” and the appreciation of that experience is the product of my life’s twists and turns too. If I was to trace my history with the STS program, it extends back to the US tracking station in Seychelles in 1981 and the launch of the first shuttle mission. The relay tracking station, one of many around the world, was tasked with keeping the data link with the orbiters when they were overhead. NASA sent astronauts out to the distant relay stations to act as ambassadors prior to the missions. As a young child of a Sri Lankan engineer attached to the UN, this was my introduction to the STS program when the astronauts visited and passed out their autographed official pictures. Reflecting on those humble beginnings, I could not help reminisce that 30 years later I had been physically present at the launch site for the last decade of missions and had the privilege of an up-close detailed view of the program. This view would not be complete without a final visit to a “live” orbiter to document the scene with my own eyes and camera. My final STS mission was to preserve the sight on the flight deck for history.
As much time as the orbiters have spent in Space, they have spent even more time on Earth being prepared for their missions. Standing in the shadow of the 526 feet tall Vehicle Assembly Building (VAB) are three tan colored nondescript square shaped buildings that could easily be disregarded as bland unimportant government buildings. Closer scrutiny shows that each of the three building have large garage style doors on one face with a distinct vertical opening for the passage of a tall aircraft tail. These three buildings represent the Orbiter Processing Facilities (OPF) 1, 2, and 3 and have been the hangers for all 5 orbiters over their 30 year operational life. Now in the twilight of the Space Transport System, OPF 1 and 2 hold “Atlantis” and “Discovery”. The two orbiters are behind the large garage doors jacked approximately 20 feet up into the air and completely swaddled in metal scaffolding undergoing post flight processing and preparation for their final mission. The third and final orbiter “Endeavour” is parked in High Bay 4 of the VAB awaiting her turn in the OPFs.
The environment of the OPF is tightly regulated and that extends to access. Uniformed guards, fences and large gates ring the OPFs. While entering the OPFs is a controlled task, entering a space shuttle orbiter inside an OPF is probably one of the world’s most controlled events (even if one is not planning on riding it up into space). All cellular phones, car keys and any device that may emit radio frequency are secured outside the large hanger. After passing through multiple concentric perimeters of security with armed guards, dogs and cameras there is a final access control point at the Ops Desk of OPF. At this desk, the name and visit purpose is again checked versus a prior authorization list and – once cleared – access to the orbiter is granted. The final access control point is the guard at the “white room” that leads to the open door of the orbiter. The white room is a sealed and climate controlled clean room environment that extends into the cabin and flight deck of the orbiter.
Shoe covers are donned before one steps into an active air puffer system that blows and sucks particles from one’s clothes and gear. Traditionally, clean suits and head covers would be worn but with no more missions for the orbiters, that formality is skipped. Passing the rack of emergency breathing apparatus on the wall, the path ends at the middeck hatch to Space Shuttle orbital vehicle 104 AKA “Atlantis.”
The ground is lined with sticky tape that acts like fly paper, removing debris from the soles of one’s feet and trapping particles. The walls of the white room have the prominent signatures of those who have passed through before you including astronauts and visiting dignitaries such as the then Prime Minister of the United Kingdom, Margret Thatcher and previous shuttle crews. This includes the crew of STS-107 who were lost on “Columbia.”
Entry into “Atlantis” is via the port side round hatch and that requires a crawl across a white foam mat into the middeck. A round air duct is also in the entry way bringing fresh cooled air into the cabin. The crawl leads to the mid deck of ‘Atlantis”. The 2,325-cubic-foot crew station module is a three-section pressurized working, living and stowage compartment in the forward portion of the orbiter. It consists of the flight deck, the middeck/equipment bay and an airlock. There are two ladders on both sides of the middeck that lead up to the flight deck. The mid deck is no bigger than a small room and is lined with compartments in the front for equipment. The back wall leads to the airlock that an astronaut would use to go for any Extra Vehicular Activity (a spacewalk) or access the International Space Station.
The ladders to the flight deck are steep and narrow with a tiny opening on the floor of the flight deck. It would be relatively easy in a weightless environment to float from the mid deck to the flight deck with no ladder in place but in a terrestrial environment it is quite a bruising effort to delicately and gracefully climb with equipment onto the fight deck. The forward flight deck has the commander’s seat positioned on the left and the pilot’s seat on the right with a center console. As a nod to the very high flight time of the astronaut pilots and the traditional “pilot/co-pilot” terminology is avoided and replaced by “commander/pilot” to indicate seating and control. The commander flies the ascent and decent.
The flight deck is designed in the usual pilot/copilot arrangement, which permits the vehicle to be piloted from either seat and permits one-man emergency return. Each seat has manual flight controls, including rotation and translation hand controllers, rudder pedals and speed-brake controllers. However, it is not a yoke as seen in conventional American airliners but a joystick control similar to the modern fighter jets and other “fly-by-wire” aircraft. The two jump seats would be at the rear edge of the center console. The flight deck seats four. The back of the flight deck has the rear facing windows and controls of the remote arm as well as another set of controls so that the orbiter can be guided by a pilot looking out of the rear or overhead windows.
The on-orbit displays and controls are at the aft end of the flight deck/crew compartment.
The displays and controls on the right are for operating the orbiter, and those on the left are for operating and handling the payloads. More than 2,020 separate displays and controls are located on the flight deck.
Six pressure windshields, two overhead windows and two rear-viewing payload bay windows are located in the upper flight deck of the crew module, and a window is located in the crew entrance/exit hatch located in the midsection, or deck, of the crew module.
One is taken back by the array off switches of various hues, shapes and sizes that adorn almost every surface of the flight deck. In between the racks of switches, light blue strips and squares of Velcro are pasted on to the instrument panels. These are silent reminders of the chaos of the zero gravity on-orbit environment and the need to corral the multitude of checklists and equipment that fill up the routine of the astronauts in Space. The Multifunction Electronic Display Subsystem (MEDS) or “glass cockpit” is an unmistakable feature that dominates the flight deck. It is hard to imagine that prior to STS-101 in April 2000; the orbiters did not have them. “Atlantis” was the first orbiter to get the cockpit upgrade and flew it on that mission. All the other orbiters go the upgrade and it has been a very successful addition.
MEDS replaced four cathode ray tube displays and 32 gauges and electromechanical displays with a total of 11 active matrix liquid crystal flat-panels, full-color displays in the Shuttle cockpit. Nine flat-panel screens are located in the forward cockpit and two in the aft cockpit. The new “glass cockpit” was 75 pounds lighter and used less power than the older model, and its color displays provide easier pilot recognition of key shuttle functions. MEDS upgrade improves crew/orbiter interaction with easy-to-read, graphic portrayals of key flight indicators like attitude display and mach speed. It represents a number of important modifications that have been accomplished on the Orbiter’s flight deck. This enhanced safety on the orbiters by providing multiple backup display functions and brought the Space Shuttle cockpit displays up to date with technology that is now common in many commercial airliners.
The Space Shuttle is a “fly-by-wire vehicle” hence all switches and buttons are connected to computers. The entire flight from launch to landing is under computer control. Special software is uploaded into the computers prior to each mission and it is tailor made for a specific mission profile. Astronauts monitor and take control of the computers at certain crucial occasions. These computers are called the Data Processing System (DPS). DPS not only flies the shuttle, but also monitors and controls all of its systems (main engines, solid rocket boosters, power supplies, environmental control, etc.) DPS collects data from vehicle sensors and crew input, performs calculations to analyze that data, and issues commands to vehicle hardware. DPS also displays vehicle information to the astronaut crew and transmits it down to the support team on the ground.
The heart of DPS is its five General Purpose Computers (GPCs). Five identical GPCs aboard the orbiter control space shuttle vehicle systems. They are shock proof, cosmic radiation proof 64 lb black boxes with computer chips inside that run the software to operate the Shuttle and distributed across the orbiter to increase likelihood of survival. GPCs 1 and 4 are located in forward middeck avionics bay 1, GPCs 2 and 5 are located in forward middeck avionics bay 2, and GPC 3 is located in aft middeck avionics bay 3. The five GPCs are IBM AP-101 computers.
GPCs are so important that four of them are configured as redundant to each other. They run the exact same software called the Primary Avionics Systems Software (PASS). The shuttle software was written in HAL/S, a special-purpose high-level language. All four stay in constant communication to make sure each is working as expected. If one fails, the crew can perform an automatic switchover to the fifth GPC. This computer is loaded with the Backup Flight Software (BFS), which as the name suggests, is a backup to the primary software as is made by a different vendor. The 5 GPCs check their own status and also that of each other and engage in a voting system to remove a failed GPC or GPCs from the decision making process. A 5X5 illuminated matrix on the overhead panel above the dashboard indicates the GPC status to the crew.
Computers may be the heart of the Orbiter and in control of all phases of flight but they still are dependent on human input and control. On the very last mission of ‘Atlantis”, she experienced a GPC failure that triggered an alarm awakening the sleeping astronauts. Commander Chris Ferguson awoke to activate a backup computer. The failure was in GPC-4 which was responsible for systems management when the alarm activated. Ferguson responded by switching the systems management duties to GPC-2. 40 minutes later, Atlantis returned to normal operations. Earlier, GPC-3 temporarily failed during the July 10 rendezvous and docking phase of the 13 day STS-135 supply mission to the International Space Station. A simple reboot got GPC-3 back on track.
Exposed to the harsh environment of space and the rigors of launch and landing, the orbiters and her sub components have constantly battled to protect its occupants and it is indeed a feat of human engineering. Mortally wounded by debris from the external tank on launch day, “Columbia’s GPC computers automatically commanded the orbiter to change her decent flight path as searing hot plasma gasses started eating away at her internal left wing structure thus effecting her decent profile. She tried to save herself and crew in one last ditch effort-such was the testament of the engineering of the orbiters. “Atlantis” has 33 missions to her credit with 306 days 14 hours 12 minutes 43seconds in space covering 125,935,769 miles and 4,848 orbits of Earth starting from her first flight on Oct 03rd, 1985 (mission STS-51-J) and ending on July 8, 2011 (mission STS-135). Standing on the flight deck of ‘Atlantis”, one realizes that her accomplishments are astounding and, truly, mind boggling to a terrestrial bound observer.
Suresh A. Atapattu/ Florida Skies.
Special contribution to Americaspace
Article has been previous published in Florida Skies and NYC Aviation
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