Apollo 15, Lunar surface
Encyclopedia
Apollo 15
Commander David Scott
and Lunar Module Pilot James Irwin
spent three days on the Moon and a total of 18½ hours outside the spacecraft on lunar extra-vehicular activity
. The mission was the first not to land in a lunar mare
, instead landing at the base of the Apennine Mountains, near Hadley Rille
. The crew explored the area using the first Lunar rover
allowing them to travel much further from the Lunar Module
lander than had previously been possible. They collected a total of 77 kg (170 lb) of lunar surface material.
the engine to direct the thrust through the center of gravity
of the LM, it then thrusted up to 100%. Irwin confirmed that the Abort Guidance System (AGS) agreed with the Primary Guidance and Navigation System (PGNS) on their height and rate of descent.
At three minutes the computer rolled the spacecraft so that they were now on their back, with the windows facing away from the lunar surface. This was so the landing radar could acquire the surface. Scott then announced the altitude and velocity lights, indicating the computer was getting acceptable data from the radar. Six minutes into the burn they were 30,000 feet (9000 m) above the surface.
In Mission Control, the Flight Director learned that tracking data indicated they were going to land 3000 feet (900 m) south of the targeted landing site. Although at first he decided not to tell the crew, Ed Mitchell, the CapCom, convinced him otherwise. During this time Scott was trying to see the ground through his window. He thought they were going to land as long as he could see Mount Hadley Delta. He was unable to see the Rille, something that had been possible in the simulators.
Nine minutes and ten seconds into the burn, Program 64 started on the computer and the LM pitched forward and the crew could see the ground. Using scribe marks on the window and angles read to him by Irwin, Scott found where the computer was predicting the landing site to be and then used a hand controller to move the predicted location. He did this 18 times during the landing, moving the target site a total of 338 meters (1110 feet) uprange and 409 meters (1341 feet) north.
Scott's main problem was that there was very little detail on the surface. The best images of the site only had 66 ft (20 m) resolution and photoanalysers had overenhanced the images. The main problem was overestimating the depth of craters, so as to make them have shadows at higher sun angles. Fortunately he was able to see four craters, Matthew, Mark, Luke and Index (the reason it was called Index and not John was due to Madalyn Murray O'Hair
, an outspoken atheist who had sued NASA over the reading of Genesis during Apollo 8
. Although she lost the case, NASA remained squeamish on overtly religious announcements on later flights).
Irwin began reading the altitude, rate of descent and the projected landing site. At 400 ft (120 m), the computer was switched to Program 66, designed for the landing phase. From now on Scott was flying manually. Irwin stopped reading out the projected landing site. Passing through 120 ft (37 m) Scott said he was picking up some dust. By the time they got to between 60 and 50 ft (18 to 15 m) the view outside would be completely obscured by dust.
Irwin then announced that the contact light had illuminated, indicating one of the landing probes on the LM's feet had contacted the ground. Immediately Scott cut the engine. With the extended engine bell there was a fear that it could touch the ground and cause exhaust to travel back into the engine. It is estimated that they were travelling 6.8 ft/s (2 m/s) when they hit, twice as fast as previous missions. A few seconds later, Scott informed the ground that "Okay, Houston. The Falcon is on the Plain at Hadley." Falcon was tilted nearly 10 degrees to its back left, just 5° below the maximum acceptable angle. It set down on the rim of a crater such that its engine bell was damaged, and with one of the legs in the crater. They were about 600 meters north and about 175 meters west of the targeted landing site. This was of little concern though thanks to the capabilities of the rover.
Before they ventured outside for the first time, Scott and Irwin would sleep. Both had realised that in order to be at their best for a seven hour EVA
they would need to be rested. But Scott had also learned the need to get an overview of a new survey site before venturing outside. As such he convinced mission planners to let them conduct a stand-up EVA before the first sleep period. It also gave them a stable platform to use a 500 mm telephoto lens
that was carried on this mission for the first time. The lens had been a struggle to get on board a spacecraft where weight savings were measured in pounds.
Two hours after landing, they depressurized the LM and removed the top hatch and docking mechanism. Then, Scott stood on top of the ascent engine cover and put his head outside. Looking around, Scott was familiar with the territory having spent months studying maps of the area.
Scott's first task was to take a 22 picture stereo
panorama
of the area using a 60 mm lens. Then he photographed targets of interest with the telephoto lens, and then a color panorama of the area with the 60 mm lens.
He was able to put to bed any further concerns about the use of the Rover. Radar
observations from Earth had given the impression that the area was covered in large boulders that would make it impossible to traverse with the Rover. Scott saw that there was nothing bigger than 6 to 8 inches (15 to 20 cm) near them. He then described the features he could see around him. Basically this was to give a general setting of the area and make sure there were no great surprises. Thirty minutes after opening the hatch, Scott re-entered and the hatch was closed and the Falcon repressurized.
Throughout the astronauts' sleep period, Mission Control had watched with some concern as the pressure inside descent stage oxygen
tanks of the LM slowly dropped. To conserve power during the night, the LM was run on a low data rate telemetry
stream, so Mission Control could not tell the exact cause. Unwilling to wake the crew they decided to wait until they had woken up.
In the end, Flight Director Peter Frank chose to wake the crewmen an hour early and got them to turn back on the high data rate telemetry. With this they saw that the valve of the Urine
Transfer Device was open even though the receptacle was capped. A total of about 8 out of 95 pounds (3.6 out of 43 kg) of oxygen had been lost. About half of the total amount was reserve. Scott and Irwin would state in the post-flight Technical Debrief that Mission Control should have awakened them as soon as the leak was detected.
Once they were awake, it was decided to start their preparations for the first lunar EVA of their mission. As with everything in Apollo, it was an involved procedure. Not only did they have to prepare Falcon, but had to don their space suit
s. Apollo 15 was the first crew that got to sleep in long johns
rather than having to stay in their space suits. It would not be until four hours after waking up that Mission Control gave the Go to depressurize the LM.
As Scott became the seventh man to step onto the lunar surface, he said:
After inspecting the LM, Scott began to unpack the Modularised Equipment Stowage Assembly (MESA), which was attached to the side of the LM and carried the TV camera
, sample bags, batteries
, CO2
scrubber
s for the space suits, and other equipment needed while the astronauts were outside the spacecraft. About seven minutes after Scott stepped outside Irwin is on the surface.
Irwin's first task was to collect a contingency sample of lunar rock. This was collected in case of an emergency i.e. suddenly having to leave the lunar surface within the first few minutes. In such an event having a contingency sample meant that the crew would not return to earth empty-handed. However, the contingency sample was not of much value because the ground surrounding the landing site had been disturbed by the LM descent engine.
After Scott positioned the TV camera on a tripod
so Mission Control could see the deployment of the Lunar Rover, he and Irwin began the process by pulling on two lanyard
s. These released the Rover and let it swing down on hinges. As it did, it began to unfold. They experienced some problems at first due to the angle the LM was sitting on, but within minutes it was on the ground almost ready to go.
Scott had the honor of the first test drive, taking it around the LM. The Rover had both front and back steering, but Scott found that only the rear-wheel steering was working (mysteriously the front steering would be working at the start of the second EVA). Other difficulties came from how their space suits did not bend very much when they sat down. When training on Earth, their body weight had forced the suits down, but on the Moon, they ended up reclining in the seats. Apart from the steering there were no other problems and the crew set about loading up the Rover for their first geological traverse.
The astronauts could not travel any farther than the distance they could walk with the remaining oxygen in their Portable Life Support Systems (PLSS). So the earlier they set out, the farther they could travel. They would travel to the farthest point of the traverse and then work their way back. On EVA-1 they would travel to the base of Hadley Delta via the Rille. Their first target was the crater dubbed Elbow crater, so-called as it sat at a bend in the Rille. The first EVA also served an important task of working out exactly where they had landed. The Rover carried a navigation system that could calculate the distance and direction of a known starting point. By travelling to a known point this could be calibrated.
Scott set off at 9 km/h (6 mph), slow by terrestrial standards, but due to the lowness of the chassis of the Rover and the roughness of the surface, the astronauts would say it seemed quite quick. Throughout the journey, the astronauts had trouble identifying where they were. Due to not knowing exactly where the landing site was and over-enhanced maps, little was familiar. But the route chosen for this first drive had been picked with this in mind. By driving along the side of the rille it would be hard to miss their target.
After arriving at Elbow, Irwin's first task is to take a panaroma of the site. At the same time Scott aligned the S-band antenna of the Rover with the Earth. This allowed Mission Control to operate the TV camera. Ed Fendell was in charge of controlling the camera and took his own pan so geologists in the backroom could see the site. The backroom kept track of everything that astronauts did on geology. As a sample was collected they would note its number, location and description on a card.
Scott and Irwin took a radial sample of the crater, taking samples at increasing distances in a straight line from the rim of the crater. After placing the photocalibration gnomon
to the west of each sample, it was photographed, before being collected and placed into a numbered bag. Within ten minutes they had gathered four rock samples and it was time to move onto Station 2 — St George.
Five hundred meters south of Elbow was the 2 km wide St George crater. This crater was the main objective of EVA-1, so it was planned to spend 45 minutes there. The flight plan had called for them to use the crater as a way of investigating the interior of Hadley Delta by collecting its ejecta. But as they approached they found there was no ejecta so it was decided not to bothering visiting the rim of St George. Instead they travelled to a boulder sitting in the open by a 6 meter crater.
The rock they stopped at was about 5 feet (1.5 m) across. The larger a rock is, the more likely it was formed in the area, instead of being thrown there by an impact. Firstly they took a soil sample at the base of the rock, then another from a small depression down the hill a bit. Scott announced that after this they would roll the rock over and sample the soil from underneath it. After a couple of futile attempts they managed to chip some pieces off it. In A Man on the Moon Andrew Chaikin writes that Dale Jackson of USGS
was having dinner with some astronauts that night in Houston and happily proclaimed that "they did everything but fuck that rock". Other samples in the area were made using a specially designed rake
with tine
s spaced 1 cm apart to collect small pebbles from the regolith
. The last task at Station 2 was to take a core sample. This was done using a tube driven into the ground by a hammer.
Mission Control announced that it had decided to cancel a planned stop at a crater named Flow due to time constraints. As such the astronauts boarded the Rover and drove back past Elbow and on their way to the LM. About 125 meters before a crater named Rhysling, Scott spied a large piece of vesicular
basalt
sitting by itself. Not wanting to just leave it there, he stopped the Rover. The stop was unplanned so he just told Mission Control his seatbelt had come loose, but quickly got off the Rover, ran over to the rock, using his collection tongs for a calibration in the photos, took a sample and got back to the Rover. During this time, Irwin distracted Mission Control by describing the surrounding craters. It was not until the sample boxes returned to Earth that the stop was discovered.
Back at Falcon, Scott and Irwin set about deploying the Apollo Lunar Surface Experiment Package (ALSEP). Scott would drill the holes for the heat-flow experiment and put in the probes, while Irwin would set up the rest of the equipment. The ALSEP consisted of the passive seismic
experiment, lunar surface magnetometer
, solar wind
spectrometer, suprathermal ion detector, cold cathode
gauge experiment, lunar dust detector and the heat-flow experiment. Not included in the ALSEP but deployed by Irwin as well were the Lunar Laser Ranging Experiment
(LRRR) and the solar wind composition experiment. The ALSEP equipment was attached via cables to the Central Station powered by an radioisotope thermoelectric generator
.
Scott had major trouble with the drilling. The first 40 cm were easy, but from then on it became more and more difficult. After 1.6 m, half of what was planned, he could get no further and Mission Control told him to just emplace the probes and start on the next hole. The extreme torque
had locked the chuck
meaning it had to be freed with a wrench, further delaying him. He could only get 1 meter into the ground on the second hole before Mission Control called it a day and told them to return to the LM.
They had been outside for 6½ hours. Returning to the LM gave the crew a much needed rest. Irwin was dehydrated
as his water bag hadn't worked, and he had gone over seven hours without liquids.
After making a navigation stop at Spur, they started to travel the 1.9 mi (3 km) along the base of the Delta to reach Station 5, at a site named Front. Scott found there was little variation in the surroundings and decided that Front was going to offer little difference, so it was decided to stop at a site about 1.9 mi (3 km) from St George and 320 ft (100 m) up to the Delta. It was interesting work, with the slope being about 10 degrees. Not reaching Front cancelled Station 5, placing them instead at Station 6.
They first sampled a fresh looking 1 meter crater, that was part of the rim of the older 3 meter crater. More samples were made above the area where they had parked the Rover. Most were breccias, but they did find one porphyritic
basalt
.
Scott decided to move down to a 40 ft (12 m) crater, which was the largest one nearby. He went down inside it to sample, but found most of the rocks to be too large. Mission Control called up and said they would like the crew to dig a trench to study the soil mechanics and take a core sample. Irwin dug the trench, which Scott photographed. Then the core sample was taken from inside the crater.
Returning the Rover, they drove 650 ft (200 m) to a large boulder. Even walking short distances on the slope was time consuming so it was easier to just have the crew use the Rover to get there. The boulder was 10 ft (3 m) across. It was necessary for one crewmember to stay by the Rover, holding it to make sure it didn't slide down the hill, which was now had a 15 degrees slope. With time running out on the stop, Scott was able to confirm what Irwin had seen earlier — the rock had a greenish tinge. The color was found to come from magnesium oxide
.
Back on the Rover, they travelled onwards to Spur crater, which was 320 ft (100 m) across and 66 ft (20 m) deep. Reaching the crater's rim they found small fragments, including one with a white vein
. At first Irwin thought he had kicked up some green soil, but Scott found it was just caused by the visors of the helmets which were coated gold
.
It was then that they saw what would become the most famous lunar sample collected during the entire Apollo program — sample #15415 or as it was dubbed by the media, the "Genesis Rock
". It looked at first just like a partially crystalline rock, but the closer they looked they realised it was almost pure plagioclase
, meaning it was anorthosite
. It was originally thought they had found a piece of the Moon's primordial crust, but later analysis would show that the rock was only 4.1 ± 0.1 billion years old, which is younger than the Moon itself, and was formed after the Moon's crust solidified. But it was still an extremely old sample, and was from the pre-Imbrian
era.
With time running out, and the walk-back constraint approaching, the geology backroom made the decision that they wanted the astronauts to collect as many small fragments as they could from the area. Irwin had wanted to sample a large breccia
but after spending so much time on #15415, there was little time left at the site. They also took some rake samples, netting 78 fragments from the regolith
. With only three minutes before they had to move on, Irwin hit a large rock with his scoop, breaking it along one of its fracture
lines. The chip they collected would be the second largest rock collected on the mission.
They returned to Falcon along the same path as they came. Passing the South Cluster and Dune, Scott decided to stop and collect some samples. Joe Allen, the CapCom, warned them that they only had ten minutes to spend here. Irwin's camera jammed, forcing Scott to take all the documentation photography. Quickly working they collected a couple of samples.
On returning to the LM, Scott began another attempt at drilling holes for the heat-flow experiment. Irwin took some manual core samples from around the ALSEP site. Again like the previous day the drill continued to get stuck, refusing to go any further. Scott was able to advance a few centimeters by pulling the drill up to clear the flutes on the drill bit
and then letting the drill advance only using its own weight. This process however would cause the drill bit sections to come apart meaning what Scott was really doing was creating a new obstruction below the surface without realising. When he tried to emplace the probes they only went in 3 ft (1 m). Post-flight analysis would find that the drill design was flawed, with the flutes too close together at the joint joining the sections of the stem.
A soil mechanics experiment was undertaken by digging a trench and using a penetrometer
to measure the strength of the regolith. Scott began drilling another hole, this time for a deep core sample. At 2.4 meters, Scott decided to this was far enough as they were well below the depth of the heat-flow probes, the main reason for taking the core sample
. Not wanting to lose time the next day returning to remove the core, he started to pull it out. He managed to get it up 20 cm but then it refused to move any further.
The last task of the day was to set up the flag of the United States
. They were outside Falcon for 7 hours and 12 minutes.
Before setting off to the ALSEP site, the crew took some customary publicity shots of them and the flag.
Back at the core sample drill both Scott and Irwin grabbed hold of the drill and tried to pull it out. Slowly but surely they managed to work it out of the ground by getting up under the drill. A few more tries and it was completely out of the ground. When they came to break the stem apart they found that a vice built into the Rover for the purpose had been installed backwards. Scott by this time was becoming more and more annoyed at the amount of time being spent on this sample and said "How many hours do you want to spend on this drill, Joe?"
Analysis of the core samples found that pebble concentration and density varied dramatically. Along the 7.9 ft (2.4 m) length of the sample, there were more than 50 distinct layers, varying in thickness from 0.2 to 8.2 inches (0.5 to 21 cm). Of particular interest was the fact that the deepest portions of the core samples were too deep for cosmic ray
s to penetrate, meaning that they had not been affected by recent cosmic ray activity.
The Rover TV camera was having problems. Any attempt to pan up or down would cause it to flop down, leaving it pointing uselessly at the ground and requiring an astronaut to repoint it.
After making a 16 mm film
of the Rover driving for the engineers on Earth, they set off for the main target of their last EVA, Hadley Rille. On the way they stopped to photograph a rock they suspected had formed a crater nearby. Unfortunately there was no time to stop and sample it.
They arrived at a 50 ft (15 m) crater near to their original target crater, Scarp. Scott decided to stop here as it met the original objective of Scarp which was to collect debris from near the rille. After taking a panorama of the site, Scott took some samples finding them to be extremely soft. It is thought that the area around them was the youngest ever walked on by an astronaut.
Moving on they travelled to the Rille. One of the objectives of Apollo 15 was to sample exposed bedrock
at its point of origin. On previous missions, the basalt collected had been thrown there by impacts. As Irwin took the site panaroma, Scott used the 500 mm telephoto lens to image the far side of the Rille, which was about 0.6 mi (1 km) across. They were looking for layering in the wall of the Rille, which could help geologists to find if the lava flows that had filled Palus Putredinis
came in one go or over time.
Irwin started a radial sample. He found a rectangular rock that was too large to return to Earth. Due to the slope of the surrounding area he was able to see some bedrock below the rim of the Rille that appeared to be above them further along. They walked to a 10 ft (3 m) crater and sampled the meter sized rocks that it had thrown up.
It was meant to be time to move on again, but the geology backroom decided that the loss of another sampling station was offset by the chance of sampling true bedrock. So they were given more time. Moving down to the very edge of the Rille they sampled a large 7 ft (2 m) rock. Back at the Rover they took another rake sample and a core sample. Scott then decided to sample a vug
gy, coarsely grained basalt. He decided to take the whole football shaped rock. Dubbed "Great Scott" the 21 lb (9.5 kg) sample would be the biggest returned on Apollo 15. They moved onto the last station of the Mission, Station 10. With little time left, all they could do was photograph the site at a 200 ft (60 m) crater.
Scott had one more thing to do once he returned to the LM:
And they did. Scott then drove the Rover for the last time to a point 300 ft (90 m) from the LM so that it could observe the liftoff. He placed a small Bible
on the hand controller and then walked about 20 ft (6 m) to a small hollow where he placed a plaque bearing the names of the fourteen known astronauts and cosmonauts to have lost their lives (two cosmonaut deaths had not been made public at the time — Valentin Bondarenko
and Grigori Nelyubov
). Beside it he placed a "Fallen Astronaut
" statuette.
They were outside the LM for 4 hours and 50 minutes.
Apollo 15
Apollo 15 was the ninth manned mission in the American Apollo space program, the fourth to land on the Moon and the eighth successful manned mission. It was the first of what were termed "J missions", long duration stays on the Moon with a greater focus on science than had been possible on previous...
Commander David Scott
David Scott
David Randolph Scott is an American engineer, test pilot, retired U.S. Air Force officer, and former NASA astronaut and engineer, who was one of the third group of astronauts selected by NASA in October 1963...
and Lunar Module Pilot James Irwin
James Irwin
James Benson Irwin was an American astronaut and engineer. He served as Lunar Module pilot for Apollo 15, the fourth human lunar landing; he was the eighth person to walk on the Moon.-Early life:...
spent three days on the Moon and a total of 18½ hours outside the spacecraft on lunar extra-vehicular activity
Extra-vehicular activity
Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...
. The mission was the first not to land in a lunar mare
Lunar mare
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...
, instead landing at the base of the Apennine Mountains, near Hadley Rille
Mons Hadley
Mons Hadley is a massif in the northern portion of the Montes Apenninus, a range in the northern hemisphere of the Moon. The selenographic coordinates of this peak are 26.5° N, 4.7° E. It has a height of 4.6 km and a maximum diameter of 25 km at the base.To the southwest of this mountain...
. The crew explored the area using the first Lunar rover
Lunar rover
The Lunar Roving Vehicle or lunar rover was a battery-powered four-wheeled rover used on the Moon in the last three missions of the American Apollo program during 1971 and 1972...
allowing them to travel much further from the Lunar Module
Apollo Lunar Module
The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back...
lander than had previously been possible. They collected a total of 77 kg (170 lb) of lunar surface material.
Landing
At 104 hours, 30 minutes and 12 seconds GET the descent engine of Falcon ignited. Burning at about 10% for the first 26 seconds so that the guidance computer could gimbalGimbal
A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to remain immobile regardless of the motion of its support...
the engine to direct the thrust through the center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...
of the LM, it then thrusted up to 100%. Irwin confirmed that the Abort Guidance System (AGS) agreed with the Primary Guidance and Navigation System (PGNS) on their height and rate of descent.
At three minutes the computer rolled the spacecraft so that they were now on their back, with the windows facing away from the lunar surface. This was so the landing radar could acquire the surface. Scott then announced the altitude and velocity lights, indicating the computer was getting acceptable data from the radar. Six minutes into the burn they were 30,000 feet (9000 m) above the surface.
In Mission Control, the Flight Director learned that tracking data indicated they were going to land 3000 feet (900 m) south of the targeted landing site. Although at first he decided not to tell the crew, Ed Mitchell, the CapCom, convinced him otherwise. During this time Scott was trying to see the ground through his window. He thought they were going to land as long as he could see Mount Hadley Delta. He was unable to see the Rille, something that had been possible in the simulators.
Scott's main problem was that there was very little detail on the surface. The best images of the site only had 66 ft (20 m) resolution and photoanalysers had overenhanced the images. The main problem was overestimating the depth of craters, so as to make them have shadows at higher sun angles. Fortunately he was able to see four craters, Matthew, Mark, Luke and Index (the reason it was called Index and not John was due to Madalyn Murray O'Hair
Madalyn Murray O'Hair
Madalyn Murray O'Hair was an American atheist activist and founder of the organization American Atheists and its president from 1963 to 1986. One of her sons, Jon Garth Murray, was the president of the organization from 1986 to 1995, while she remained de facto president during these nine years....
, an outspoken atheist who had sued NASA over the reading of Genesis during Apollo 8
Apollo 8
Apollo 8, the second manned mission in the American Apollo space program, was the first human spaceflight to leave Earth orbit; the first to be captured by and escape from the gravitational field of another celestial body; and the first crewed voyage to return to Earth from another celestial...
. Although she lost the case, NASA remained squeamish on overtly religious announcements on later flights).
Irwin began reading the altitude, rate of descent and the projected landing site. At 400 ft (120 m), the computer was switched to Program 66, designed for the landing phase. From now on Scott was flying manually. Irwin stopped reading out the projected landing site. Passing through 120 ft (37 m) Scott said he was picking up some dust. By the time they got to between 60 and 50 ft (18 to 15 m) the view outside would be completely obscured by dust.
Irwin then announced that the contact light had illuminated, indicating one of the landing probes on the LM's feet had contacted the ground. Immediately Scott cut the engine. With the extended engine bell there was a fear that it could touch the ground and cause exhaust to travel back into the engine. It is estimated that they were travelling 6.8 ft/s (2 m/s) when they hit, twice as fast as previous missions. A few seconds later, Scott informed the ground that "Okay, Houston. The Falcon is on the Plain at Hadley." Falcon was tilted nearly 10 degrees to its back left, just 5° below the maximum acceptable angle. It set down on the rim of a crater such that its engine bell was damaged, and with one of the legs in the crater. They were about 600 meters north and about 175 meters west of the targeted landing site. This was of little concern though thanks to the capabilities of the rover.
Stand-up EVA
Extra-vehicular activity
Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...
they would need to be rested. But Scott had also learned the need to get an overview of a new survey site before venturing outside. As such he convinced mission planners to let them conduct a stand-up EVA before the first sleep period. It also gave them a stable platform to use a 500 mm telephoto lens
Telephoto lens
In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus...
that was carried on this mission for the first time. The lens had been a struggle to get on board a spacecraft where weight savings were measured in pounds.
Two hours after landing, they depressurized the LM and removed the top hatch and docking mechanism. Then, Scott stood on top of the ascent engine cover and put his head outside. Looking around, Scott was familiar with the territory having spent months studying maps of the area.
Scott's first task was to take a 22 picture stereo
Stereoscopy
Stereoscopy refers to a technique for creating or enhancing the illusion of depth in an image by presenting two offset images separately to the left and right eye of the viewer. Both of these 2-D offset images are then combined in the brain to give the perception of 3-D depth...
panorama
Panorama
A panorama is any wide-angle view or representation of a physical space, whether in painting, drawing, photography, film/video, or a three-dimensional model....
of the area using a 60 mm lens. Then he photographed targets of interest with the telephoto lens, and then a color panorama of the area with the 60 mm lens.
He was able to put to bed any further concerns about the use of the Rover. Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
observations from Earth had given the impression that the area was covered in large boulders that would make it impossible to traverse with the Rover. Scott saw that there was nothing bigger than 6 to 8 inches (15 to 20 cm) near them. He then described the features he could see around him. Basically this was to give a general setting of the area and make sure there were no great surprises. Thirty minutes after opening the hatch, Scott re-entered and the hatch was closed and the Falcon repressurized.
EVA-1
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
tanks of the LM slowly dropped. To conserve power during the night, the LM was run on a low data rate telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...
stream, so Mission Control could not tell the exact cause. Unwilling to wake the crew they decided to wait until they had woken up.
In the end, Flight Director Peter Frank chose to wake the crewmen an hour early and got them to turn back on the high data rate telemetry. With this they saw that the valve of the Urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
Transfer Device was open even though the receptacle was capped. A total of about 8 out of 95 pounds (3.6 out of 43 kg) of oxygen had been lost. About half of the total amount was reserve. Scott and Irwin would state in the post-flight Technical Debrief that Mission Control should have awakened them as soon as the leak was detected.
Once they were awake, it was decided to start their preparations for the first lunar EVA of their mission. As with everything in Apollo, it was an involved procedure. Not only did they have to prepare Falcon, but had to don their space suit
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...
s. Apollo 15 was the first crew that got to sleep in long johns
Long underwear
Long underwear, also called long johns, Granny pantys, or thermal underwear, is a style of two-piece underwear with long legs and long sleeves that is normally worn during cold weather. It offers an advantage over the one-piece union suit in that the wearer can choose to wear either the top,...
rather than having to stay in their space suits. It would not be until four hours after waking up that Mission Control gave the Go to depressurize the LM.
As Scott became the seventh man to step onto the lunar surface, he said:
- "As I stand out here in the wonders of the unknown at Hadley, I sort of realize there's a fundamental truth to our nature. Man must explore. And this is exploration at its greatest."
After inspecting the LM, Scott began to unpack the Modularised Equipment Stowage Assembly (MESA), which was attached to the side of the LM and carried the TV camera
Apollo TV camera
Television cameras used on the Apollo Project's missions varied in design, with image quality improving significantly with each design. A camera was carried in the Apollo Command Module...
, sample bags, batteries
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
, CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
scrubber
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
s for the space suits, and other equipment needed while the astronauts were outside the spacecraft. About seven minutes after Scott stepped outside Irwin is on the surface.
After Scott positioned the TV camera on a tripod
Tripod (photography)
In photography, a tripod is used to stabilize and elevate a camera, or to support flashes or other photographic equipment. All photographic tripods have three legs and a mounting head to couple with a camera...
so Mission Control could see the deployment of the Lunar Rover, he and Irwin began the process by pulling on two lanyard
Lanyard
A lanyard is a rope or cord exclusively worn around the neck or wrist to carry something. Usually it is used where there is a risk of losing the object or to ensure it is visible at all times. Aboard a ship, it may refer to a piece of rigging used to secure objects...
s. These released the Rover and let it swing down on hinges. As it did, it began to unfold. They experienced some problems at first due to the angle the LM was sitting on, but within minutes it was on the ground almost ready to go.
Scott had the honor of the first test drive, taking it around the LM. The Rover had both front and back steering, but Scott found that only the rear-wheel steering was working (mysteriously the front steering would be working at the start of the second EVA). Other difficulties came from how their space suits did not bend very much when they sat down. When training on Earth, their body weight had forced the suits down, but on the Moon, they ended up reclining in the seats. Apart from the steering there were no other problems and the crew set about loading up the Rover for their first geological traverse.
The astronauts could not travel any farther than the distance they could walk with the remaining oxygen in their Portable Life Support Systems (PLSS). So the earlier they set out, the farther they could travel. They would travel to the farthest point of the traverse and then work their way back. On EVA-1 they would travel to the base of Hadley Delta via the Rille. Their first target was the crater dubbed Elbow crater, so-called as it sat at a bend in the Rille. The first EVA also served an important task of working out exactly where they had landed. The Rover carried a navigation system that could calculate the distance and direction of a known starting point. By travelling to a known point this could be calibrated.
Scott set off at 9 km/h (6 mph), slow by terrestrial standards, but due to the lowness of the chassis of the Rover and the roughness of the surface, the astronauts would say it seemed quite quick. Throughout the journey, the astronauts had trouble identifying where they were. Due to not knowing exactly where the landing site was and over-enhanced maps, little was familiar. But the route chosen for this first drive had been picked with this in mind. By driving along the side of the rille it would be hard to miss their target.
After arriving at Elbow, Irwin's first task is to take a panaroma of the site. At the same time Scott aligned the S-band antenna of the Rover with the Earth. This allowed Mission Control to operate the TV camera. Ed Fendell was in charge of controlling the camera and took his own pan so geologists in the backroom could see the site. The backroom kept track of everything that astronauts did on geology. As a sample was collected they would note its number, location and description on a card.
Gnomon
The gnomon is the part of a sundial that casts the shadow. Gnomon is an ancient Greek word meaning "indicator", "one who discerns," or "that which reveals."It has come to be used for a variety of purposes in mathematics and other fields....
to the west of each sample, it was photographed, before being collected and placed into a numbered bag. Within ten minutes they had gathered four rock samples and it was time to move onto Station 2 — St George.
Five hundred meters south of Elbow was the 2 km wide St George crater. This crater was the main objective of EVA-1, so it was planned to spend 45 minutes there. The flight plan had called for them to use the crater as a way of investigating the interior of Hadley Delta by collecting its ejecta. But as they approached they found there was no ejecta so it was decided not to bothering visiting the rim of St George. Instead they travelled to a boulder sitting in the open by a 6 meter crater.
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
was having dinner with some astronauts that night in Houston and happily proclaimed that "they did everything but fuck that rock". Other samples in the area were made using a specially designed rake
Rake (tool)
A rake is a broom for outside; an horticultural implement consisting of a toothed bar fixed transversely to a handle, and used to collect leaves, hay, grass, etc., and, in gardening, for loosening the soil, light weeding and levelling, removing dead grass from...
with tine
Tine
Tine may have one of the following meanings:*Tine – a 'prong' on a fork or similar implement, or any similar structure*Tine – the biggest dairy producer in Norway...
s spaced 1 cm apart to collect small pebbles from the regolith
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...
. The last task at Station 2 was to take a core sample. This was done using a tube driven into the ground by a hammer.
Mission Control announced that it had decided to cancel a planned stop at a crater named Flow due to time constraints. As such the astronauts boarded the Rover and drove back past Elbow and on their way to the LM. About 125 meters before a crater named Rhysling, Scott spied a large piece of vesicular
Vesicular texture
Vesicular texture is a volcanic rock texture characterised by a rock being pitted with many cavities at its surface and inside. The texture is often found in extrusive aphanitic, or glassy, igneous rock...
basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
sitting by itself. Not wanting to just leave it there, he stopped the Rover. The stop was unplanned so he just told Mission Control his seatbelt had come loose, but quickly got off the Rover, ran over to the rock, using his collection tongs for a calibration in the photos, took a sample and got back to the Rover. During this time, Irwin distracted Mission Control by describing the surrounding craters. It was not until the sample boxes returned to Earth that the stop was discovered.
Back at Falcon, Scott and Irwin set about deploying the Apollo Lunar Surface Experiment Package (ALSEP). Scott would drill the holes for the heat-flow experiment and put in the probes, while Irwin would set up the rest of the equipment. The ALSEP consisted of the passive seismic
Passive seismic
Passive seismic is the detection of natural low frequency earth movements, usually with the purpose of discerning geological structure and locate underground oil, gas, or other resources. Usually the data listening is done in multiple measurement points that are separated by several hundred meters,...
experiment, lunar surface magnetometer
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...
, solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
spectrometer, suprathermal ion detector, cold cathode
Cold cathode
A cold cathode is a cathode used within nixie tubes, gas discharge lamps, discharge tubes, and some types of vacuum tube which is not electrically heated by the circuit to which it is connected...
gauge experiment, lunar dust detector and the heat-flow experiment. Not included in the ALSEP but deployed by Irwin as well were the Lunar Laser Ranging Experiment
Lunar laser ranging experiment
The ongoing Lunar Laser Ranging Experiment measures the distance between the Earth and the Moon using laser ranging. Lasers on Earth are aimed at retroreflectors planted on the moon during the Apollo program, and the time for the reflected light to return is determined...
(LRRR) and the solar wind composition experiment. The ALSEP equipment was attached via cables to the Central Station powered by an radioisotope thermoelectric generator
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
.
Scott had major trouble with the drilling. The first 40 cm were easy, but from then on it became more and more difficult. After 1.6 m, half of what was planned, he could get no further and Mission Control told him to just emplace the probes and start on the next hole. The extreme torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
had locked the chuck
Chuck (engineering)
A chuck is a specialized type of clamp used to hold an object, usually an object with radial symmetry, especially a cylindrical object. It is most commonly used to hold a rotating tool or a rotating workpiece...
meaning it had to be freed with a wrench, further delaying him. He could only get 1 meter into the ground on the second hole before Mission Control called it a day and told them to return to the LM.
They had been outside for 6½ hours. Returning to the LM gave the crew a much needed rest. Irwin was dehydrated
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
as his water bag hadn't worked, and he had gone over seven hours without liquids.
EVA-2
The target of the second EVA was Mount Hadley Delta again, but the crew drove via a more direct route and to a site east of where they had travelled the previous day. Travelling at 5.5 mph (9 km/h) they made good time across the plain. The first stop of the day, Station 4 was cancelled to give them more time to finish the drilling the holes for the heat flow experiment. This was at a crater Dune, on the western edge of the South Cluster.After making a navigation stop at Spur, they started to travel the 1.9 mi (3 km) along the base of the Delta to reach Station 5, at a site named Front. Scott found there was little variation in the surroundings and decided that Front was going to offer little difference, so it was decided to stop at a site about 1.9 mi (3 km) from St George and 320 ft (100 m) up to the Delta. It was interesting work, with the slope being about 10 degrees. Not reaching Front cancelled Station 5, placing them instead at Station 6.
Porphyry (geology)
Porphyry is a variety of igneous rock consisting of large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass. The larger crystals are called phenocrysts...
basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
.
Scott decided to move down to a 40 ft (12 m) crater, which was the largest one nearby. He went down inside it to sample, but found most of the rocks to be too large. Mission Control called up and said they would like the crew to dig a trench to study the soil mechanics and take a core sample. Irwin dug the trench, which Scott photographed. Then the core sample was taken from inside the crater.
Returning the Rover, they drove 650 ft (200 m) to a large boulder. Even walking short distances on the slope was time consuming so it was easier to just have the crew use the Rover to get there. The boulder was 10 ft (3 m) across. It was necessary for one crewmember to stay by the Rover, holding it to make sure it didn't slide down the hill, which was now had a 15 degrees slope. With time running out on the stop, Scott was able to confirm what Irwin had seen earlier — the rock had a greenish tinge. The color was found to come from magnesium oxide
Magnesium oxide
Magnesium oxide , or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium . It has an empirical formula of and consists of a lattice of Mg2+ ions and O2– ions held together by ionic bonds...
.
Back on the Rover, they travelled onwards to Spur crater, which was 320 ft (100 m) across and 66 ft (20 m) deep. Reaching the crater's rim they found small fragments, including one with a white vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
. At first Irwin thought he had kicked up some green soil, but Scott found it was just caused by the visors of the helmets which were coated gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
.
It was then that they saw what would become the most famous lunar sample collected during the entire Apollo program — sample #15415 or as it was dubbed by the media, the "Genesis Rock
Genesis Rock
The Genesis Rock is a sample of Moon retrieved by Apollo 15 astronauts James Irwin and David Scott in 1971 during their second lunar EVA.Chemical analysis of the Genesis Rock indicated it is an anorthosite, composed mostly of the plagioclase feldspar, anorthite. The rock was formed in the early...
". It looked at first just like a partially crystalline rock, but the closer they looked they realised it was almost pure plagioclase
Plagioclase
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...
, meaning it was anorthosite
Anorthosite
Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar , and a minimal mafic component...
. It was originally thought they had found a piece of the Moon's primordial crust, but later analysis would show that the rock was only 4.1 ± 0.1 billion years old, which is younger than the Moon itself, and was formed after the Moon's crust solidified. But it was still an extremely old sample, and was from the pre-Imbrian
Upper Imbrian
In the Lunar geologic timescale, the Late Imbrian epoch occurred between 3800 million years ago to about 3200 million years ago. It was the epoch during which the mantle below the lunar basins partially melted and filled them with basalt...
era.
With time running out, and the walk-back constraint approaching, the geology backroom made the decision that they wanted the astronauts to collect as many small fragments as they could from the area. Irwin had wanted to sample a large breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
but after spending so much time on #15415, there was little time left at the site. They also took some rake samples, netting 78 fragments from the regolith
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...
. With only three minutes before they had to move on, Irwin hit a large rock with his scoop, breaking it along one of its fracture
Fracture
A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...
lines. The chip they collected would be the second largest rock collected on the mission.
They returned to Falcon along the same path as they came. Passing the South Cluster and Dune, Scott decided to stop and collect some samples. Joe Allen, the CapCom, warned them that they only had ten minutes to spend here. Irwin's camera jammed, forcing Scott to take all the documentation photography. Quickly working they collected a couple of samples.
On returning to the LM, Scott began another attempt at drilling holes for the heat-flow experiment. Irwin took some manual core samples from around the ALSEP site. Again like the previous day the drill continued to get stuck, refusing to go any further. Scott was able to advance a few centimeters by pulling the drill up to clear the flutes on the drill bit
Drill bit
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
and then letting the drill advance only using its own weight. This process however would cause the drill bit sections to come apart meaning what Scott was really doing was creating a new obstruction below the surface without realising. When he tried to emplace the probes they only went in 3 ft (1 m). Post-flight analysis would find that the drill design was flawed, with the flutes too close together at the joint joining the sections of the stem.
A soil mechanics experiment was undertaken by digging a trench and using a penetrometer
Penetrometer
A penetrometer is a device to test the strength of a material such as soil. There are many types of penetrometer. They are usually round or cone shaped. The penetrometer is dropped on the test subject or pressed against it and the depth of the resulting hole is measured. The measurements determine...
to measure the strength of the regolith. Scott began drilling another hole, this time for a deep core sample. At 2.4 meters, Scott decided to this was far enough as they were well below the depth of the heat-flow probes, the main reason for taking the core sample
Core sample
A core sample is a cylindrical section of a naturally occurring substance. Most core samples are obtained by drilling with special drills into the substance, for example sediment or rock, with a hollow steel tube called a core drill. The hole made for the core sample is called the "core hole". A...
. Not wanting to lose time the next day returning to remove the core, he started to pull it out. He managed to get it up 20 cm but then it refused to move any further.
The last task of the day was to set up the flag of the United States
Flag of the United States
The national flag of the United States of America consists of thirteen equal horizontal stripes of red alternating with white, with a blue rectangle in the canton bearing fifty small, white, five-pointed stars arranged in nine offset horizontal rows of six stars alternating with rows...
. They were outside Falcon for 7 hours and 12 minutes.
EVA-3
Overnight, Mission Control decided to cancel the traverse to the North Complex. Time saved not going there would be spent on pulling out the deep core sample. Although annoyed by this, Scott understood that although he was in command of the Mission, he was part of a team, and the mission scientists had decided that the core sample was more important than sampling the North Complex.Back at the core sample drill both Scott and Irwin grabbed hold of the drill and tried to pull it out. Slowly but surely they managed to work it out of the ground by getting up under the drill. A few more tries and it was completely out of the ground. When they came to break the stem apart they found that a vice built into the Rover for the purpose had been installed backwards. Scott by this time was becoming more and more annoyed at the amount of time being spent on this sample and said "How many hours do you want to spend on this drill, Joe?"
Analysis of the core samples found that pebble concentration and density varied dramatically. Along the 7.9 ft (2.4 m) length of the sample, there were more than 50 distinct layers, varying in thickness from 0.2 to 8.2 inches (0.5 to 21 cm). Of particular interest was the fact that the deepest portions of the core samples were too deep for cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
s to penetrate, meaning that they had not been affected by recent cosmic ray activity.
The Rover TV camera was having problems. Any attempt to pan up or down would cause it to flop down, leaving it pointing uselessly at the ground and requiring an astronaut to repoint it.
After making a 16 mm film
16 mm film
16 mm film refers to a popular, economical gauge of film used for motion pictures and non-theatrical film making. 16 mm refers to the width of the film...
of the Rover driving for the engineers on Earth, they set off for the main target of their last EVA, Hadley Rille. On the way they stopped to photograph a rock they suspected had formed a crater nearby. Unfortunately there was no time to stop and sample it.
They arrived at a 50 ft (15 m) crater near to their original target crater, Scarp. Scott decided to stop here as it met the original objective of Scarp which was to collect debris from near the rille. After taking a panorama of the site, Scott took some samples finding them to be extremely soft. It is thought that the area around them was the youngest ever walked on by an astronaut.
Moving on they travelled to the Rille. One of the objectives of Apollo 15 was to sample exposed bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
at its point of origin. On previous missions, the basalt collected had been thrown there by impacts. As Irwin took the site panaroma, Scott used the 500 mm telephoto lens to image the far side of the Rille, which was about 0.6 mi (1 km) across. They were looking for layering in the wall of the Rille, which could help geologists to find if the lava flows that had filled Palus Putredinis
Palus Putredinis
Palus Putredinus is an area of the lunar surface that stretches from the crater Archimedes southeast toward the rugged Montes Apenninus range located on the southeastern edge of Mare Imbrium. This region is a nearly level, lava-flooded plain bounded by the crater Autolycus to the north and the...
came in one go or over time.
Irwin started a radial sample. He found a rectangular rock that was too large to return to Earth. Due to the slope of the surrounding area he was able to see some bedrock below the rim of the Rille that appeared to be above them further along. They walked to a 10 ft (3 m) crater and sampled the meter sized rocks that it had thrown up.
Vug
Vugs are small to medium-sized cavities inside rock that may be formed through a variety of processes. Most commonly cracks and fissures opened by tectonic activity are partially filled by quartz, calcite, and other secondary minerals. Open spaces within ancient collapse breccias are another...
gy, coarsely grained basalt. He decided to take the whole football shaped rock. Dubbed "Great Scott" the 21 lb (9.5 kg) sample would be the biggest returned on Apollo 15. They moved onto the last station of the Mission, Station 10. With little time left, all they could do was photograph the site at a 200 ft (60 m) crater.
Scott had one more thing to do once he returned to the LM:
- "Well, in my left hand, I have a featherFeatherFeathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
; in my right hand, a hammerHammerA hammer is a tool meant to deliver an impact to an object. The most common uses are for driving nails, fitting parts, forging metal and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure. The usual features are a handle and a head,...
. And I guess one of the reasons we got here today was because of a gentleman named Galileo, a long time ago, who made a rather significant discovery about falling objects in gravity fields. And we thought where would be a better place to confirm his findings than on the Moon. And so we thought we'd try it here for you. The feather happens to be, appropriately, a falcon feather for our Falcon. And I'll drop the two of them here and, hopefully, they'll hit the ground at the same time."
And they did. Scott then drove the Rover for the last time to a point 300 ft (90 m) from the LM so that it could observe the liftoff. He placed a small Bible
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...
on the hand controller and then walked about 20 ft (6 m) to a small hollow where he placed a plaque bearing the names of the fourteen known astronauts and cosmonauts to have lost their lives (two cosmonaut deaths had not been made public at the time — Valentin Bondarenko
Valentin Bondarenko
Valentin Vasiliyevich Bondarenko was a Soviet fighter pilot and cosmonaut. He died during a training accident in Moscow, USSR, in 1961. A crater on the Moon's far side is named for him.-Education and military training:...
and Grigori Nelyubov
Grigori Nelyubov
Grigori Grigoyevich Nelyubov was a Soviet cosmonaut who was likely to have been the third or fourth person in space before his dismissal from the Soviet space program....
). Beside it he placed a "Fallen Astronaut
Fallen Astronaut
Fallen Astronaut is an 8.5 cm aluminium sculpture of an astronaut in a spacesuit which commemorates astronauts and cosmonauts who died in the advancement of space exploration...
" statuette.
They were outside the LM for 4 hours and 50 minutes.