Friday, April 13, 2012

"We have got a problem" Apollo 13 failed flight and successful return to earth

Men Leave Main Craft for 'Lifeboat' After an Oxygen Leak
By John Noble Wilford

Front Page Image

Special to The New York Times

Houston, Tuesday, April 14 - The Apollo 13 Astronauts, their lives threatened by a serious oxygen leak, were forced to evacuate their command ship late last night and use their intended moon-landing craft as a "lifeboat" for a fast return to the earth.

In cool and cryptic words, they were instructed by mission control here to use the attached lunar module's rocket to power them back to an emergency splashdown in the Pacific Ocean at about noon on Friday.

There will be great risks and little margin for error or delay.

At a news conference here officials were asked if there was enough oxygen to get the astronauts back to earth safely. A space agency official answered, "Yes."

"I'm glad to hear it," the questioner said.

The lunar landing module has a supply of 48 pounds of oxygen.

Christopher C. Kraft, deputy director of the Manned Spacecraft Center, said:

"I think their chances are excellent at the moment, assuming their lunar module operates all right."

Emergency Simulated

Houston officials were asked if "this abort situation or altered trajectory had ever been run on simulators, in just this way?"

"Oh yes, many times," the officials said. "We've run all kinds of abort situations. The Lunar module is designed to carry out the maneuver. We are looking even at the possibilities of dropping the service module, but that particular type of maneuver has not been tested in flight and we'd have to make ourselves certain that we could control the spacecraft under that kind of inertia condition."

The plan is for the three men to keep the hatch open between the lunar module. One of the astronauts will remain in the command module. One of the astronauts will remain in the command module part of the time to monitor its systems, and it will be necessary to keep the hatch open in order to draw on the lunar module's oxygen supply.

Because of the space limitations in lunar module, it is expected that two of the astronauts will crawl through to the command module to stretch out when it is time to go to sleep. A third astronaut will always remain awake in the lunar module to watch for any possible malfunctions.

The lunar module is a two-section spacecraft. Its descent stage contains the fuel and rocket for lunar landing, but cannot hold astronauts. The ascent stage, which is 12 feet four inches high and 14 feet, one inch wide, is the astronauts' lifeboat.

Mr. Kraft, who has served as a flight director or mission executive on all of the nation's manned spaceflights, added that this is "as serious a situation as we have ever had in manned spaceflight."

Capt. James A. Lovell Jr. Of the Navy, the commander, and his two civilian co-pilots, Fred W. Haise Jr. and John L. Swigert Jr., crowded into the two-man lunar module at about 11:40 P.M. Eastern standard time.

Flight controllers were still not sure what happened to cause the massive oxygen leak in the command ship. Was it a meteoroid strike? Or some jarring explosion on board?

"Something happened, and it was a very violent thing," James A. McDivitt, a former astronaut and current spacecraft manager, said. "But as far as what exactly happened, I have no idea."

Under questioning, Mr. McDivitt conceded that a meteoroid hit was a possibility but said that many other factors could be involved. Engineers are now examining radioed data for clues.

The greatest concern at the moment, however, was getting the three astronauts back. Only once before has an American-manned spaceship been in sufficient trouble to require an emergency landing. That was Gemini 8, commanded by Neil A. Armstrong, which tumbled out of control in 1966 because of a wild-firing control rocket.

Flight controllers said they were hoping to bring Apollo 13 down to a Pacific splashdown, although the recovery site may have to be moved somewhat to the southwest of the original area.

If necessary, especially if it is decided to rush the astronauts' return, the splashdown could come in the Atlantic Ocean off South America. However, there is no trained recover fleet standing by there and the pickup would have to be made by, as space agency officials said, "ships of opportunity."

To get back to the earth, they must swing around the moon while moving on their present course and then use the lunar gravity to bend them earthward and the lunar module's rocket to give them power and refined direction. It will take less rocket energy that way then to turn back before reaching the moon.

The planned 62-hour return trip is the shortest possible. The lunar module, although designed primarily for landing on the moon, was said to have enough oxygen and enough storage-battery electricity to see the three men through the emergency.

After sweeping behind the moon, the Apollo astronauts are to fire up the lunar module's 10,000-pound-thrust rocket, the one ordinarily used for descending to the moon.

Ordinarily, the homeward journey from lunar orbit is initiated with the rocket housed in the rear compartment of the command ship.

But the lack of oxygen, which is used to generate electricity in the command ship as well as for breathing, makes it impossible to operate the guidance and triggering mechanisms for the 20,500-pound-thrust rocket.

Under this alternate mission plan, the astronauts will ride the lunar module nearly all the way back to earth. Shortly before they reach the earth's atmosphere, which extends about 400,000 feet up in the sky, they must crawl back through the connecting tunnel to their command ship.

Only the command ship- a cone-shaped and heavily shielded vehicle- is capable of withstanding the intense heat of the 25,000-mile-an-hour re-entry into the atmosphere towards splashdown.

The last thing the astronauts did before leaving their command ship was to route their remaining oxygen supply into a small reserve tank.

This will serve as their breathing oxygen for the final minutes from re-entry to splashdown. The lunar module will have to be jettisoned shortly before re-entry.

Flight controllers were reasonably confident that the lunar module's propulsion system and its life-support system would be sufficient for the flight to a splashdown in the planned recovery area. The aircraft carrier Iwo Jima is standing by there.

Under the new plan, Apollo 13 should swing around the moon tonight. That is the time they were to have rocketed into lunar orbit- but that is not to be.

The trouble came up suddenly. The three astronauts had just completed a routine telecast from inside their spacecraft, so routine that no commercial television networks bothered to broadcast it.

All systems appeared to be "go" for man's third lunar landing attempt.

Then Mr. Haise radioed the ominous words: "We've got a problem."

At first, it seemed to be only an electrical problem. Two of three fuel cells, which generate electricity through a chemical reaction between liquid hydrogen and liquid oxygen, went awry. This occurred at about 10 P.M.

Apollo 13, which was launched from Cape Kennedy, Fla., on Saturday, was more than 203,000 miles from the earth, approaching its target on the moon's ancient hills of Fra Mauro.

For nearly an hour, flight controllers worked with the astronauts by radio before it was finally determined there was no chance of continuing with the mission as planned. One look outside the spacecraft window was indicative.

"We're venting something out into space," Captain Lovell, the Apollo 13 commander, reported. "It's a gas of some sort."

This was the first serious, cliff-hanging development in any of the nation's five flights to the vicinity of the moon, including three lunar landing attempts.

A few hours before, Gerald Griffin, one of the flight directors, was describing Apollo 13 as "a nice, easy flight so far."

There was some concern even earlier over the landing craft's propellant pressurization system. The super-cold helium used to force the flow of propellant into the descent rocket ran some abnormally high pressures early in the countdown preparations at Cape Kennedy, Fla. But, after a day of testing, the helium tank was held acceptable for launching.

Captain Lovell and Mr. Haise crawled through the connecting tunnel into the lunar module at 8:40 P.M. to inspect the vehicle's systems, as planned. They were instructed by flight controllers to make a special check of helium pressures.

Based on calculations by mission control, the pressure in the helium tank should have risen since launching to about 710 pounds a square inch, which would be acceptable. But if it were found to be running between 770 and 800, the astronauts would be asked to make an additional check early tomorrow.

Some build-up of pressure is normal during a flight. Although the basketball-size tank is double-walled like thermos bottle, some heat leaks in and causes the super-cold liquid to expand.

But Captain Lovell reported after turning on the power in the lunar module that the helium pressures were running between 710 and 720.

"That's the number we were looking for," mission control told Apollo 13.

At the time, Apollo 13 was 201,395 miles from earth, traveling at 2,260 miles an hour.

The crew had one momentary scare early today while they were still sleeping. The "master-alarm" buzzer went off in the cockpit, alerting them to a slightly low pressure in one of the hydrogen tanks supplying fuel for the spacecraft's electricity-generating plant.

Although the problem was quickly corrected by turning on a heater in the tank system, Captain Lovell later told Mission Control, "We were all over the cockpit like a wet noodle."

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