Joe Allen announced that the Station 3 stop was being eliminated and directed the astronauts to return to the LM in order to deploy the surface experiment packages. Because the astronauts would return to the base of Hadley Delta in the specific area of the Apennine Front during EVA-2, it was felt that there would be no loss of science. Scott and Irwin climbed onto the rover and prepared to return to Falcon.
"We suggest you just follow your navigation system home," Allen told the lunar explorers.
"That's a good idea," Scott answered. "I was going to say we might try that just to see how she works.''
"That's exactly our thinking,'' Allen replied. Once they were strapped in, Scott and Irwin relied on the LRV's navigation system to give them their proper heading. They had a commanding view in front of them because they were at the highest elevation of their first EVA. However, they could not see the Lunar Module from their location because of the much closer horizon caused by the Moon's smaller diameter relative to the Earth.
"One thing we were always somewhat aware of,'' Scott recalled during the interview with the author, "was that when you are on the Moon you go over the
horizon quickly and you don't see the LM. We were the first crew to travel over the horizon and be out of sight of the LM - a big change in planning and preparation. And so on our first excursion, the backup navigation to get back to the LM was the old 'Hansel and Gretel' trick of following your tracks. Once we were comfortable after the first EVA, then we'd take a side excursion and come back a different way. But in the process of planning this, we knew to use the Sun compass, so that if the navigation system broke down or didn't work, we could still find our way back. But the system worked brilliantly on the Moon, although you had to have some method of navigation other than your tracks and the rover system itself.''
With the front steering inoperative, steering the rover on the lunar surface was a delicate procedure. As they were descending the side of St. George Crater, traveling at only five kilometers per hour, Scott maneuvered to avoid some blocks and the rover spun around.
''You can't go fast downhill in this thing,'' Scott told Houston, ''because if you try and turn with the front wheels locked up like that, they dig in and the rear end breaks away, and around you go. And we just did a 180.''
As Scott turned the rover around and continued his return to the LM, the GM and Boeing teams at the Cape and in Houston redoubled their efforts to resolve the problem of the inoperative front steering. Seven-and-a-half minutes into their return, the astronauts spotted a reflection off the LM, directly ahead of them. The navigation system was working perfectly, and Scott grew increasingly comfortable driving the LRV.
''It's easy to drive,'' Scott told Allen, ''no problem at all. We just have to be careful because of the locked front wheels, but other than that, it's very responsive. I can put the throttle right up to the stop or at some intermediate position; and take my hand off and rest my hand. If I want to go left or right, I just put a little pressure until I get the angle I want and then let it off and we re-center on the steering. It's really neat, even with the locked front wheels.''
''Sounds mighty smooth, Dave,'' Allen concurred. ''And we're still working on your front wheel problem. We may have them back before you know it.''
Less than two kilometers from the LM, Scott spotted a small vesicular basalt rock that caused him to literally stop in his tracks. The rock was striking, with its dark black appearance. Exercising his prerogative as Commander, Scott decided he had to have it as a sample, but feigned a problem with his seatbelt, knowing Allen would probably discourage him from taking the time to get the sample. Irwin immediately caught on, first complaining about having dropped his map. While Scott went to the rear of the rover to get the sample tongs and then walked over to the desired sample, Irwin launched into a description of some of the craters he had observed for the benefit of Houston, but also to cover for Scott, who was photographing the area before and after taking the sample. Scott then returned to the rover, stowed the tongs, placed the bagged sample under his seat and climbed back onto the rover. CapCom Allen suspected what was actually going on but said nothing, and the geologists in the Backroom exchanged knowing glances. In less than two minutes, Scott had accomplished an unplanned sample collection, including the photography. The speed and ease with which Scott was able to accomplish this was the result of the functionality and operability of the LRV's crew station and the ability to get off and on easily. This had been conceived, planned and rehearsed for lunar operations. Back on the rover, Scott was able to buckle his seatbelt quickly, and they resumed their return to the LM. Just over half-an-hour after leaving St. George Crater, the astronauts were back at their Lunar Module.
Their task now was to deploy the Apollo Lunar Surface Experiments Package (ALSEP). The astronauts choose a site 100 meters from the LM to deploy the ALSEP. First the Central Station was placed, followed by the Radioisotope Thermal Generator which supplied the power for the ALSEP. The experiments deployed included the Passive Seismic Experiment, the Lunar Surface Magnetometer, the Suprathermal Ion Detector Gauge, the Lunar Dust Collector, the Heat Flow Experiment and the Solar Wind Spectrometer, which Scott deployed just prior to reentering the LM. The Heat Flow Experiment required two holes to be drilled in the lunar surface to a depth of 3 meters. Problems with the drill stems removing soil bogged the drilling operation down and Scott could get no further than 1.7 meters in depth. He tried to drill a second core, but with the same result. Scott thought he had hit a large rock, preventing him from drilling deeper, but it later turned out that it was a design flaw in the drill stem. Removing the drill stems proved just as much of a chore and consumed more time than had been planned for. Scott had parked the LRV near the ALSEP deployment site so the activity could be watched by Houston and once it was completed, Scott and Irwin boarded the rover again. In order to save precious time, they did not take the time to fasten their seatbelts. Getting on and off the rover in /6 gravity in a stiff pressure suit was considerably different than their training on Earth, where they had the benefit of the Earth's gravity and the suits were not pressurized. They could not bend the suits at the waist easily sitting on the rover while on the Moon. Scott drove the rover at less than 5 kph so that they would not be tossed from their seats. Despite the effectiveness of the LRV's fenders, there was still a coating of lunar dust on the vehicle.
''Okay, Joe, there's quite a bit of dust on the mirror on the LCRU,'' Scott told Houston. ''As a matter of fact, there's quite a bit of dust all over the Rover. It's a very fine kind of dust. Do you want us to brush that off?''
''Dave, maybe a token effort, but don't take too long; it doesn't sound too serious to us,'' Allen assured Scott. After some rudimentary dusting of the rover, Allen directed Scott to completely open the LRV battery covers, open the LCRU blanket thirty-five per cent, and then power down the LCRU. Scott asked Houston what he could do with the time remaining. The Solar Wind Spectrometer had yet to be deployed and Houston suggested he do so. Although he had not trained to deploy the experiment for the mission - this was Irwin's task - Scott had done so in training as backup for the Apollo 12 crew. He had Irwin talk him through it, however, and the experiment was deployed in five minutes.
There was still a most important duty to perform before closing out EVA-1, which was to plant the American flag and take the requisite photographs. The Hadley-Apennine region proved most photogenic. The color photo taken by Irwin of Scott saluting the flag, with the Lunar Module Falcon, the Lunar Rover and Hadley Delta looming in the background, has become an icon of Apollo photography. This photo was actually taken at the start of EVA-3 with a new color film magazine in Irwin's camera. The position of all these elements were actually carefully worked out in the simulator building at KSC months before. The only difference was the orientation of the rover, which was changed to provided better battery cooling between the second and third EVAs.
The lunar samples were safely secured inside one of the Sample Return Containers (SRCs), known as a ''rock box.'' Scott re-entered the LM, the cabin was re-pressurized and the astronauts then went through the process of removing their suits. The astronauts communicated with their Command Module Pilot, Al Worden, and told him of the success they had had. Scott and Irwin spent the next several hours organizing their cramped quarters, cleaning up as much as possible, having their food bars and drinks, and discussing their day's activities with Houston before finally going to sleep.
EVA-2: EXPLORING THE APENNINE FRONT
Scott and Irwin both had a good night's rest, although on the nearside of the Moon, the Sun never sets. The crew got their wakeup call from CapCom Gordon Fullerton, who moments later handed over the CapCom duties to Joe Allen. The crew discussed the day's plans for the scheduled six-and-a-half-hour EVA-2 with Allen, and went through a long list of items on the check list prior to donning their suits and depressurizing the cabin. The astronauts egressed from Falcon and went about their tasks preparing the rover for their second EVA. Scott and Irwin kept communication flowing to CapCom Joe Allen, who helped the crew in their sequential planned chores.
''Joe,'' Scott said to Allen, ''I'm in a position to take another crack at that steering, if you'd like to talk me through the procedures.''
''Okay, Dave,'' Allen responded. ''We want you to exercise the Forward Steering switch by cycling from Bus A to Bus C and back several times, and then stop with the switch finally at Bus Charlie.''
''Steering Forward is now in Bus Charlie, and I cycled it three times'' Scott answered.
''Okay, Dave. Now proceed with your normal power-up cycle if you haven't already; and give me a call when you're ready to start driving.''
The astronauts finished the items on their Cuff Check List. Scott performed the Bus cycling procedure once again, and then moved the T-handle. The front steering responded.
''You know what I bet you did last night, Joe?'' Scott asked with amazement, ''You let some of those Marshall guys come up here and fix it, didn't you?''
''They've been working, that's for sure,'' Allen replied, smiling.
''It works, Dave?'' Irwin asked, incredulous.
''Yes, sir. It's working, my friend,'' the Commander answered.
''Lot of smiles on that one, Dave,'' Allen radioed. ''We might as well use it today.''
"Boeing has a secret booster somewhere to take care of their Rover!" Scott exclaimed. He drove the LRV away a short distance to a level spot to reset the navigation and told Allen that the rover operated so much better with both forward and rear steering. Many people remained baffled over the forward steering anomaly, but Sam Romano and Ference Pavlics at GM both suspected what the problem might actually have been.
"Our suspicion was," Pavlics recalled, "that because the Lunar Module landed in a fairly early part of the lunar morning and the vehicle was sitting in a shaded area, the temperature was still very cold in that shade. Because of the cold temperature, the conductive plastic potentiometer which was controlling the steering function did not make contact. So our recommendation was just to exercise the joystick back and forth, left and right many times to heat up and possibly reestablish electrical contact. That probably happened as the system warmed up."
The astronauts continued their preparations for the day's station stops. Based on the results of their explorations during EVA-1, Station 4 and Station 5 would be eliminated from this traverse. Their first stop was Station 6 at the base of the
Apennine Front. Scott found that driving the rover with the dual Ackermann steering operating was almost too much when traveling at more than 5 kph.
''Hey, Joe, the steering is a new task,'' Scott observed. ''It's really responsive now. I guess I got pretty used to quiet steering, and this thing really turns!'' ''Roger, Dave. We don't want it to be too easy for you,'' Allen replied. ''Hey, look. We can always disengage the rear steering,'' Irwin told Scott ''No, I'll get used to it. It's just a matter of getting used to,'' he reassured Houston. However, Scott found the LRV to be almost too sensitive with both front and rear steering, and wanted to try it with just front steering. He brought the rover to a stop to disengage the rear steering, telling Houston that the double Ackermann steering was too responsive when traveling at speed and with a lack of traction due to the wheels leaving the ground over bumpy lunar surfaces. The seatbelts were continually proving their worth.
''You get this floating sensation on the Moon,'' Scott said during this author's interview, ''and you've got to have the seatbelts or you float right out of the seat. That became apparent very early. And then you get a lot of feedback through the suit when you're on a bumpy surface because you are tied to the rover by the seatbelt. Through the suit your arm feeds back into the hand controller, which was sort of a challenge. Because of the feedback of the bumps, you're constantly changing the steering, and even the speed. So, that was one of the things we had to be careful of.''
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