Apollo 14 Preliminary Science Report, NASA SP 272, 1971, p. 36; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); Astronautics and Aeronautics 1971, NASA SP 4016, 1972, pp. 27, 41, 43; Astronautics and Aeronautics 1970, NASA SP 4015, 1972, p. 338; Roundup, MSC, December 4, 1970, P. 1; A Man on the Moon, Andrew Chaikin, 1994, pp. 369-375; To a Rocky Moon, Donald Wilhelms, 1993, pp. 250-255.
February 9
Apollo 14 splashdown
April 23-24
Soyuz 10/Salyut 1
June 6-29
Soyuz 11/Salyut 1
July 30
1971 EVA 3
World EVA 18
U.S. EVA 16
Lunar Surface EVA 6
Duration: 0:33 Spacecraft/mission: Apollo 15 Crew: David Scott, James Irwin, Alfred Worden Moonwalker: David Scott Purpose: Survey Hadley-Apennine landing site from top hatch of LM Falcon
This SEVA was partly a response to the surface navigation problems experienced on Apollo 14. Commander David Scott stood atop Falcon's ascent engine cover with his shoulders through the top hatch so he could get his bearings at the complex Hadley-Apennine landing site ahead of the surface EVAs. He told Edgar Mitchell in Mission Control that the site was "exactly like what you had on Apollo 14. It's very hummocky, and, as you know, in this kind of terrain you can hardly see over your eyebrows." Scott reported that 5000-m (16,500-ft) Mt. Hadley glowed gold and brown in the lunar morning sunlight, and that there were no large boulders to hinder the progress of the Lunar Roving Vehicle (LRV) during the next day's scheduled traverse south to St. George Crater.
Astronautics and Aeronautics 1971, NASA SP 4016, p. 203-204; To a Rocky Moon, Donald Wilhelms, 1993, p. 270-271; A Man on the Moon, Andrew Chaikin, 1994, pp. 414-415.
July 31
1971 EVA 4
World EVA 19
U.S. EVA 17
Lunar Surface EVA 7
Duration: 6:34 Spacecraft/mission: Apollo 15 Crew: David Scott, James Irwin, Alfred Worden Moonwalkers: David Scott, James Irwin Purpose: Deploy LRV; traverse south to St. George Crater; deploy ALSEP
Unlike the Apollo 11, 12, and 14 astronauts, Scott and Irwin waited to charge their PLSS backpacks with water until they reached the surface. Falcon landed with one footpad in a small crater, causing it to tilt. Scott estimated that, because of Falcon's cant, the backpacks tilted 30 deg during recharge. This prevented them from charging fully and created bubbles in Irwin's PLSS which set off false failure warnings throughout the first EVA. With improved A7LB space suits for longer EVAs, the LRV for greater mobility, and a complex landing site outside the equatorial "Apollo zone," Apollo 15 represented the beginning of a new era of lunar exploration. The improved EMU was more comfortable and retained provisions for the BLSS umbilical, which was stowed on the LRV for Apollos 15, 16, and 17. Added consumables meant that an astronaut could manage a 7-hr EVA and a 5-mi "walkback" if the LRV failed. New convolute joints permitted kneeling, though with some difficulty. Scott set up the improved TV camera while Irwin collected the contingency sample. The astronauts tended to move using two-footed kangaroo hops rather than slow-motion loping. Unstowing and deploying the LRV took longer than the 20 min allotted. Though it was planned as a one-man task, under lunar surface conditions unfolding the vehicle required both astronauts. The Boeing-built LRV was one of the most important additions to Apollo's capabilities. The LRV System included the rover, a structure supporting it within LM descent stage Quadrant 1, and a deployment mechanism. The LRV's empty weight was 205 kg (455 lb); loaded with two astronauts in EMUs, equipment, and lunar samples, it weighed up to 691 kg (1535 lb). The vehicle had a 35-cm (14-in) ground clearance and a 2.25-m (90-in) wheelbase, and was 3.05 m (122 in) long. Top speed was about 21 km (13 mi)/hr. Two independent sets of 36V silver-zinc batteries provided sufficient power for a 62.4-km (39-mile) traverse at 16 km (10 mi)/hr. One set was sufficient for operation. The batteries were located on the forward chassis between the front wheels. Each of the four wheels had a separate traction drive motor and was independently steerable. If a drive motor failed, the affected wheel freewheeled. The LRV had Ackerman steering—that is, it could move sideways if necessary, and could turn within its own length. Conventional steering was also available. Each wheel had a mesh wire tire with a metal chevron frame and inner frame. A T-bar handle between the seats controlled steering, braking, and acceleration. An astronaut braked the LRV by sliding the handle backward; accelerated forward by bending the handle forward; accelerated reverse by bending the handle backward; and turned the rover by bending the handle in the appropriate direction. A "dashboard" control console ahead of the T-bar displayed speed, pitch, distance traveled, bearing to last point of initialization, and distance from the LM. The rear chassis carried tools and rock boxes on EVAs. Seatbelts held the astronauts in their seats against the LRV's rolling and bouncing. A color television camera mounted on the front of the LRV could be pointed and zoomed by a controller in Houston when the LRV's high-gain antenna was aimed at the Earth. This allowed scientists to investigate traverse stops independently. Irwin took the first of several harmless Apollo 15 falls during LRV deployment. The astronauts found that the rover had no front-wheel steering, but Scott was able to maneuver the vehicle using only rear steering. They also found that their seatbelts barely fit around their pressurized EMUs. About 3 hr into the EVA Scott and Irwin set out on a 10.3-km (6.2-mi) traverse south along the rim of Elbow Crater to 2.25-km-dia (1.4-mi-dia) St. George Crater, near Hadley Rille. During the traverse the astronauts reduced suit cooling to avoid becoming cold while their metabolic rates were low. They had some difficulty with "zero phase lighting" (light reflected from the landscape opposite the Sun) which made obstacles difficult to discern. The astronauts used a rake to collect "walnut-sized samples" near St. George Crater. Flight controllers in Houston operated the LRV camera so geologists on Earth could explore the lunar landscape telerobotically and guide the astronauts in collecting samples. The astronauts then drove back to Falcon to deploy the ALSEP. They located the central station 110 m (335 ft) west of the LM and drilled a hole in the ground for the heatflow experiment probe. Scott used more oxygen than expected, so flight controllers terminated the EVA 30 min early and considered cutting back the second EVA. Dust made PLSS connectors tight and difficult to operate. After the EVA Irwin was extremely thirsty because his drink bag failed to operate (it refused to supply water during all of the Apollo 15 EVAs). In addition, both astronauts suffered pain in their fingers caused by their fingernails pressing hard against their glove fingertips. Irwin needed help to remove his gloves, and elected to trim his nails before the second EVA. Scott left his fingernails as they were to avoid reducing his dexterity.
Apollo 15 Preliminary Science Report, NASA SP 289, 1972, pp. 1.5-1.6; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); "Added Mobility Spurs Lunar Harvest," Zack Strickland, Aviation Week & Space Technology, August 9, 1971, pp. 13-17; Astronautics and Aeronautics 1971, NASA SP 4016, p. 204-205, A Man on the Moon, Andrew Chaikin, 1994, pp. 422-424; To a Rocky Moon, Donald Wilhelms, 1993, pp. 272-274; Catalog of Apollo Experiment Operations, Thomas Sullivan, NASA RP 1317, January 1994, pp. 79-83; Lunar Roving Vehicle Operations Handbook, Boeing LRV Systems Engineering, Contract NAS8-25145, November 6, 1972, pp. 1.1-1.21, 6.2-6.6; interview, David S. F. Portree with Joseph P. Loftus, Jr., May 30, 1996.
Based on their experience during the first traverse, mission planners modified the second EVA to maximize time spent doing science and minimize driving. The start of the second EVA was delayed 30 min by PLSS backpack recharge difficulties. When they did reach the surface, Scott and Irwin were delighted to discover that LRV front steering had become operational. They began a 12.5-km (7.5-mi) traverse southeast to the foot of the Hadley Delta mountain and back, passing Index, Arbeit, Crescent, Spur, and Window craters. The LRV climbed Hadley Delta's slopes at 10 kph (6 mph) with no difficulty. Scott and Irwin climbed 300 ft above Falcon, which was more than 5 km (3 mi) away. Soft material on the slopes provided poor footing, and the LRV began to slide while parked. Irwin held the rover while Scott hopped off to collect a green crystalline rock. At Spur Crater they collected the "Genesis Rock," which today is still believed to be a piece of original lunar crust more than four billion yr old. Scott called Spur a "gold mine" of interesting geological samples, so their time there was extended to 49 min. CapCom Joe Allen assisted the astronauts via the LRV camera by warning Irwin that he was about to lose his sample bag. The elevation clutch on the LRV camera began to slip. Irwin's vertical PLSS antenna snapped off, and Scott taped it on horizontally. They collected so many samples at Spur that the LRV bounced when they dropped the rock box on it. They then had to rush because they were approaching the "walkback" limit of their EMUs. In contrast to the first EVA, Scott used about as much oxygen as expected. The astronauts found navigating back to the LM difficult until they encountered their own outbound tracks. Back at Falcon, Scott drilled a core hole, encountering much resistance and hurting his hands. Then the 3-m-long (10-ft-long) core tube could not be removed. On advice from Mission Control, the astronauts abandoned the tube until the next EVA. They planted the U.S. flag at the EVA's end.
"Added Mobility Spurs Lunar Harvest," Zack Strickland, Aviation Week & Space Technology, August 9, 1971, pp. 13-17; Apollo 15 Preliminary Science Report, NASA SP 289, 1972, pp. 1.5-1.6; Apollo Lunar Surface Journal, Eric Jones, 1995 (http://www.hq.nasa.gov/office/pao/History/alsj/); To a Rocky Moon, Donald Wilhelms, 1993, pp. 275-277; A Man on the Moon, Andrew Chaikin, 1994, p. 426, 429.
August 2
1971 EVA 6
World EVA 21
U.S. EVA 19
Lunar Surface EVA 9
Duration: 4:20 Spacecraft/mission: Apollo 15 Crew: David Scott, James Irwin, Alfred Worden Moonwalkers: David Scott, James Irwin Purpose: Geological traverse west to Scarp crater and Hadley Rille
The astronauts propped their PLSS backpacks upright for charging, eliminating their bubble problems. With this EVA, the fifth of his career, Scott became the record-holder for number of career EVAs. His record was not beaten until 1984, when cosmonauts Leonid Kizim and Vladimir Solovyov performed six EVAs outside Salyut 7. The EVA started 1 hr, 45 min late to let the crew rest after they experienced irregular heartbeats. This was traced later to potassium deficiency, complicated in Irwin's case by failure of his drink bag. The EVA was shortened to protect Falcon's planned liftoff time. Scott and Irwin managed to free the core tube which became stuck on EVA 2, but could not take it apart to stow it because the LRV vise was assembled backwards on Earth. They used a wrench and lost 28 min. Irwin and Scott started their traverse 1 hr, 20 min into the EVA. They drove 5.1 km (3 mi) west to Scarp Crater, then turned northwest to Hadley Rille, with stops at Rim Crater and a feature called The Terrace. This EVA marked the first time Apollo astronauts passed out of sight of their LM. After Scott and Irwin returned to Falcon, Apollo 15 Flight Director Gerald Griffin called the LRV a "great little machine," and added that, "I hate to leave it up there." During the three traverses, the LRV was used to collect nearly 80 kg of samples and covered almost 50 km (28 mi). According to scientist-astronaut Harrison Schmitt, in training as LMP on Apollo 17, "... we had a fantastic exploration mission. There's just no question in my mind that we sent two very competent observational scientists to the Moon." The New York Times on this date pointed to the obvious success of Apollo 15 and reminded its readers that the Apollo program would end with Apollo 17. The paper lamented how a "vast and complex technology developed at the cost of billions of dollars over the last decade is being abandoned even as its vast potentialities are being demonstrated."