ulyssesonline.com

The success of the space shuttle program has given all of us a false sense of security that space exploration is routine. The recent tragedy of the space shuttle Columbia reminded us that space flight is quite dangerous, although only a handful of astronauts have been lost in the entireity of the US space program. Columbia’s break-up last week brought us back to reality that the dangers are ever present in the space program even with today’s advancing technology.

Space exploration is risky and the space shuttle is no exception. With over a hundred successful missions the last twenty years, it is interesting to note that both accidents to the space shuttle Challenger and Columbia occured during the blast-off and re-entry, the two most vulnerable times in any mission.

The problem may lie in the design of the space shuttle itself. The space shuttle requires a tremendous amount of thrust to place it in orbit. The shuttle engines are incapable of sending the ship into orbit on its own. Therefore, two booster rockets are bolted to it along with a massive fuel tank to fuel the shuttle’s three main engines. As you already know, rockets are highly explosive. Rockets are essentially explosions on one opening of a sealed metal container designed to propel itself or in this case, an aircraft attached to it.

Gregg Easterbrook wrote an article back on April 1980 in the Washington Monthly about the possible dangers the space shuttle may encounter during its ascent. He writes, “during ascent, the shuttle must withstand 3 Gs of stress–inertial drag equivalent to three times its own weight. While all five engines are screaming, there will be acoustic vibrations reaching 167 decibels, enough to kill an unprotected person. In orbit, the shuttle will drift through -250�F. vacuum, what engineers call the “cold soak.” It’s cold enough to embrittle and shatter most materials. During reentry, the ship’s skin goes from cold soak to 2,700�F., hot enough to transform many metals into Silly Putty.”

He adds, “Suppose one of the solid-fueled boosters fails. The plan is, you die. Solid rockets can fail in two ways. They can explode; enough said. Or they can shut down spontaneously. If a booster shuts down, there will be 2.5 million pounds of thrust on one side battling zero pounds on the other. Even a split second of this imbalance will send the ship twisting into oblivion, overriding any application of pilot skill.”

“Suppose one of the shuttle’s three main engines fails. You have a fighting chance. You blow the boosters off. Then, using the throttles on the remaining engines, you try to turn the beast around. It’s screaming and trembling, a vicious wounded animal. There’s that damn fuel tank hanging there, and it has all the aerodynamic grace of the Temple of Karnak. But it’s got the fuel. Ditch it and you’ve got no engines.”

“If you get twisted back around toward the Cape, you blow the fuel tank off and glide home. If the beast is too badly wounded to land, but you can slow it down to a few hundred m.p.h. before you splat into the water, you’re okay. At that speed you can eject.

Then, there’s the descent you have to worry about. Gregg Easterbrook writes, “But you’re in luck–the launch goes fine. Once you get into space, you check to see if any tiles are damaged. If enough are, you have a choice between Plan A and Plan B. Plan A is hope they can get a rescue shuttle up in time. Plan B is burn up coming back.

The shuttle starts rubbing air at Mach 25–25 times the speed of sound. At 250,000 feet, you have a little control with the reaction thrusters. By 80,000 feet, they’ve shut off, and you’re gliding. It’s silent in the ship. Just the air rushing by and the computers meeping to each other. Biting into the denser air, your elevators and speed brakes lend some control. You can still maneuver “cross range”–several hundred miles north or south relative to your approach from the west. But there are only 15 runways and lake beds in the world where you can land, so don’t get carried away.

Cross-range maneuvering is no longer possible by 50,000 feet. You’re locked in, wherever you’re going. Now you have company. Fighter planes–”chase planes”–have picked you up. They’re swarming all around you, snooping around the hull for damage. Eighteen miles from the runway, you finally slow to subsonic speed. Now you really have some options. At this low speed and altitude, you could punch out safely.

At 12,000 feet, the plummeting begins. Nose down at 24 degrees to the horizon, 30 degrees in some flights. Feels like a dive bomber. That DC-9, the one that makes your knuckles white on commercial flights, comes in at three degrees. Thirty seconds out, you can raise the nose back up. Now you have one and only one chance to lower the landing gear. No time to cycle them. If the gear don’t lock, that’s it. The chase planes are coming right down to the strip with you, following your every move like baby ducks. They snoop around the landing gear. Locked? If not, the chase pilots have a couple seconds to tell you to bail out.

Only a few more seconds. The ground isn’t coming up; some prankster from Hell is throwing it at you. Whack! Down at 220 m.p.h. Hope the rubber in those tires didn’t blow from that long cold soak. Crack! You bounce along, you roll to a stop.”

What about the tiles? The pyrolized carbon tiles are there to protect the shuttle from burning up on re-entry. These tiles can be several degrees hot on one side and cool to the touch on the other side. I actually touched one of the tiles in high school when a NASA official visited our class. Each shuttle must be fitted with 33,000 refractory tiles each one unique in shape and must be fitted individually. Tiles break often, and must be remolded painstakingly.

Gregg Easterbrook adds, “NASA designed the tiles as “safe life.” That means there is no back-up for them. If they fail, the shuttle burns on reentry. If enough fall off, the shuttle may become unstable during landing, and thus un-pilotable. The worry runs deep enough that NASA investigated installing a crane assembly in Columbia so the crew could inspect and repair damaged tiles in space. (Verdict: Can’t be done. You can hardly do it on the ground.)” This is in reference to the problems NASA had in installing these tiles on the space shuttle.

Despite its limitations and inherent dangers, the space shuttle has had a remarkable safety record over the last twenty years. Just two major catastrophes in over one hundred missions. Space travel is unforgiving. No there’s no such thing as a flat tire or blown engine where you can park a car on the side of the road and get some help. The challenges and the risks associated with space exploration is immense. There’s abosultely nothing routine about going to space.

(No Ratings Yet)

 Loading ...