Our Spaceflight Heritage: Leaping further – the flight of Apollo 15
On July 26, 1971, NASA launched one of the most ambitious and spectacular space missions in history—Apollo 15. At 9:34 a.m. EDT (12:34 GMT), the gigantic Saturn V rocket lifted off from pad A at Launch Complex 39 at Kennedy Space Center in Florida. It carried Commander Dave Scott, Command Module Pilot Al Worden, and Lunar Module Pilot Jim Irwin on their flight into history—and the Moon.
Slightly less than three hours into the flight, the S-IV-B engine reignited for Trans-Lunar Injection (TLI), and Scott, Worden, and Irwin were on their way to the Apennine Mountains of the Moon.
Apollo 15 launch. Photo Credit: NASA
After TLI, the four adapter panels on the side of the spacecraft blew away, releasing the Command and Service Module Endeavour. Worden yawed the spacecraft around and nudged it into contact with the Lunar Module (LM) Falcon, which was nestled inside the S-IV-B. After making contact and latching the two spacecraft together, Endeavour then extracted Falcon from the hollow upper stage of the rocket, and the combined spacecraft was on its way to the Moon.
Apollo 15 was a leap forward in the United States’ Apollo Moon landing program. Previous missions had been fairly short-duration, with the astronauts only able to walk modest distances from their Lunar Modules.
“I think back to the greatest period in American history and am proud that I was part of the Apollo Program and actually flew to the Moon. However, that period is an old story, and I do not see this country reaching for great technological advances as it did in the ’60s and ’70s,” Worden told SpaceFlight Insider. “We are without the kind of leadership that exhorts the country to do great things. I am also sad that we exchanged the Apollo program for a Shuttle that could not get past Earth orbit and was dangerously flawed.”
Apollo 11 had been the G mission, the first Moon landing, involving a very brief stay on the lunar surface with a two-and-a-half-hour moonwalk and Early Apollo Scientific Experiments Package (EASEP), containing a handful of basic experiments.
Apollos 12 and 14 had been H missions, staying on the Moon for two days, with two moonwalks. Apollo 14 had carried a Modular Equipment Transporter (MET), a sort of backward wheelbarrow for carrying Moon rocks, which turned out to be more trouble than it was worth.
Apollo 15 was originally intended to be another H mission, but due to budget cutbacks and the cancellation of Apollos 18, 19, and 20, it was decided to make Apollo 15 the first J mission. That meant a three-day stay on the Moon and more intensive exploration and experimentation than had ever been attempted before.
The CSM carried a Scientific Instrument Module (SIM) for an intensive orbital study of the lunar surface and astronomical observation. The LM was outfitted with extra batteries and oxygen, more surface experiments, and the Lunar Roving Vehicle (LRV), a battery-driven car that would enable the astronauts to venture farther from their LM than on any previous mission (though mission rules required them never to venture farther than they would be able to walk back, in case the LRV broke down).
There would be five Extravehicular Activities (EVA)—the first being a stand-up EVA to observe the immediate vicinity, followed by three eight-hour moonwalks, and finally a spacewalk during the flight home in order to retrieve experiments from the SIM.
On July 30, Scott and Irwin entered Falcon, undocked from Endeavour, and Scott piloted the stubby vehicle to a smooth, almost routine landing, saying on touchdown, “Okay, Houston, the Falcon is on the plain at Hadley.”
The Apollo 15 crew, Commander Dave Scott, Command Module Pilot Al Worden, and Lunar Module Pilot Jim Irwin. Photo Credit: NASA
Scott opened the top hatch and propped himself up on his elbows to look out on the lunar surface.
In an interview with the Apollo Lunar Surface Journal, Scott said, “When I stood up in the top hatch, I found that, because of the one-sixth gravity, I could support myself on my elbows without having to stand on anything, and get fairly well out of the hatch.”
For 30 minutes, Scott described what he saw. “As I look on around to the north, Mount Hadley itself is in the shadow, although I can see that the ridge line on the top of Mount Hadley. It too is smooth. I see no jagged peaks of any sort. The hill I would call number 22 on your map—in the far distance—also looks smooth, rounded; no prominent features. I’ll skip the distant field around to my 6 o’clock, because it’s all in the shadow. And looking into the Sun, of course, obliterates almost everything. As I look on down to my 7 o’clock, I guess I see Index Crater here, the near field. But, back up on Hadley to the east—Hadley Delta, why, again I can see a smooth surface.”
At 9:13 a.m. EDT (13:13 GMT), Scott climbed down the ladder and stepped onto the surface of the Moon with the words, “Okay, Houston. 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.”
Apollo 15 was the last Apollo mission to require a contingency sample. After taking that sample, Scott and Irwin set about assembling the LRV.
Many people ask how the small Lunar Module was able to transport a car to the Moon. The LRV was folded up and disassembled within the Modularized Equipment Stowage Assembly (MESA). When Scott and Irwin pulled open the compartment in which the rover was stowed, its wire mesh tired immediately popped out, and as they pulled the rover out and down, it unfolded into its familiar car shape. Then it was a matter of attaching the high-gain antenna, unfolding the seats, attaching sample bags, and attaching the television camera.
Apollo 15 was the first Moon landing mission to transmit continuous color television of every phase of the lunar surface activities. On Apollo 11, the hazy black-and-white camera was mounted on a tripod that gave a ghostly view of the static lunar module Eagle the whole time. On Apollo 12 the color TV camera stopped functioning when Alan Bean inadvertently pointed it directly at the Sun. On Apollo 14, the camera’s brightness was calibrated improperly, making Alan Shepard and Edgar Mitchell appear as bright blobs. Furthermore, it was again mounted on a tripod, so for the entire second EVA, it provided a static view of the lunar horizon when Shepard and Mitchell loped off into the mountains.
Falcon landed unevenly, causing it to tilt noticeably. Photo Credit: NASA
Apollo 15 carried a much higher quality camera, and it was mounted on the LRV, which relayed its images to Earth through a high-gain antenna with which it could be controlled from the ground. NASA engineer Ed Fendell was able, by remote control, to pan back and forth and up and down, zoom in and out and even adjust the brightness. As a result, every stage of the surface activities of the last three Moon landing missions is documented in astounding color filmmaking, except brief occasions when contact was lost, for instance during traverses in the rover.
After a 45-minute sortie at Elbow Crater, Scott and Irwin returned to Falcon to set up the ALSEP experiments. These consisted of a passive seismometer, a lunar surface magnetometer (LSM), a solar wind spectrometer, a suprathermal ion detector, a cold cathode ion gauge, a lunar dust detector, and a lunar heat flow experiment. These were attached to a central station powered by a Radioisotope Thermoelectric Generator (RTG) powered by plutonium.
Scott had considerable difficulty extracting the deep core drill after he had sunk it into the lunar soil, and the EVA ended while he was still trying to work the drill out of the hard substance beneath the surface.
The end of the first EVA was a relief for Irwin, whose water bag was not working, and he had gone for over seven hours of arduous work with no fluids. He had chosen not to mention the problem for fear of having the EVA aborted. As a result, he developed heart trouble during the mission and suffered two heart attacks in the years that followed. Irwin passed away in 1991.
The Lunar Roving Vehicle. Photo Credit: NASA
During the second EVA, Scott found the most famous find of the Apollo Program: a chunk of anorthosite that was later called the “Genesis Rock”, which was thought at the time to be a piece of the Moon’s primordial crust—though it was later determined to be only about 4 billion years old.
At the end of the EVA, Scott went back to his futile effort to extract the deep core drill, but the drill was incontrovertibly stuck, and nothing he could do could get it to come loose.
Unusually for a Moon landing mission, the American flag was not deployed until the end of EVA 2.
The next day, Scott went back to the task of trying to work his drill out of the stubborn lunar soil. He was frustrated when Mission Control canceled the traverse to the North Complex—a region to the east of Hadley Rille thought to be volcanic—so that he could complete the deep core sample.
Scott, keenly disappointed, asked CapCom Joe Allen if it was really important enough to lose the North Complex. “Just tell me it’s that important, and I’ll feel a lot better,” Scott said.
“It’s that important, Dave,” Allen said.
“Good,” Scott replied, “because then I don’t feel like I wasted so much time.”
Finally, with Irwin’s help, he was able to pull the drill loose. Unfortunately, the time was already lost, and Scott and Irwin never made it to the North Complex.
As Scott and Irwin drove around the Moon collecting rocks, in orbit above them, Al Worden was studying the lunar surface using the SIM.
“My best memory of the flight is the time I spent alone in lunar orbit. I had the freedom to do what had to be done, and I not only enjoyed it, but I think I made a significant impact during that time in terms of the science return,” Worden told SpaceFlight Insider. “And I must say, the most interesting time was when I did the deep space walk and got to see the Earth and the Moon at the same time.”
The Command Module Endeavour, with the SIM visible. Photo Credit: NASA
The SIM photographed the lunar surface, measured the heights of various lunar surface features using a laser altimeter, measured the Moon’s gravitational acceleration with the S-Band Transponder Experiment, studied the composition of the lunar dust with the X-Ray Spectrometer Experiment and the Gamma-ray Spectrometer Experiment, and measured radon emission using the Alpha Particle Spectrometer Experiment. The Orbital Mass Spectrometer Experiment measured the composition of the lunar atmosphere—contrary to popular belief, the Moon does have a very thin, tenuous atmosphere. Additionally, the Bistatic Radar Experiment measured the scattering of radar waves from the lunar surface.
At the end of the mission, Scott performed one of the most famous experiments of the Apollo Program. He stood in front of the TV camera, Falcon behind him, and held out a hammer and a feather.
“Well, in my left hand, I have a feather; in my right hand, a hammer,” Scott said, “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.”
Simultaneously, he let the hammer and feather go. Sure enough, they fell to the dusty soil simultaneously.
Audibly excited, Scott exclaimed, “How about that! Which proves that Mr. Galileo was correct in his findings.”
On Aug. 2, Falcon’s ascent stage lifted off. The liftoff was captured by the television camera, which was still mounted to the LRV. Unfortunately, the camera was having considerable difficulties panning up, and several times Fendell lost control of the camera during the third EVA and Scott had to fix it. But a few seconds of the liftoff were caught on camera as Falcon rocketed to its rendezvous with Endeavour.
Before returning to Earth, Endeavour deployed a satellite which would map the lunar gravity field, study the plasma, particle, and magnetic field environment of the Moon. It continued to function and transmit data until Jan. of 1973. In 1972, Apollo 16 would deploy an identical satellite.
The command module splashes down two of its three chutes deployed. Photo Credit: NASA
During the trip home, Worden performed a 20-minute EVA to retrieve the SIM and to inspect various instruments in order to determine what had caused various problems during the mission. To this day, Worden holds the record for the farthest-from-Earth EVA.
On Aug. 7, the command module separated from the service module and made a fiery re-entry. One of the three main parachutes failed, but the two chutes that deployed were sufficient for the capsule to splash down safely in the Pacific Ocean, where Scott, Worden, and Irwin were recovered by the U.S.S. Okinawa.
For Worden’s part, he is not inspired by what he sees coming from the space agency that he once worked with during the heady days of Apollo.
“There is no creativity in NASA today, so the next spacecraft looks just like Apollo; it will not have the capability to re-enter directly from Mars, even though there are re-entry vehicles that could. I do not believe there is a consensus in this country about what we should be doing in space, and again that is driven by our leadership,” Worden told SpaceFlight Insider, noting that things could turn around and the age of exploration that was Apollo could return. “However, I am optimistic about the future, given enough time. History tells us that, in time, the obstacles to long-term space flight will be overcome and we will go on to our true destiny, which is to another Earth some day for our species survival.”
Apollo 16 and 17 would repeat and improve upon much of Apollo 15’s success, but Apollo 15 was unique in a number of ways. One, it was the only mission in which an astronaut conducted a stand-up EVA before stepping onto the surface of the Moon. Two, it was the last time the television camera recorded an astronaut’s first footsteps on the Moon, and the only time the camera viewed the deployment of the LRV. Three, it was the last mission to collect a contingency sample.
But most importantly, as the first J mission, Apollo 15 expanded the capabilities of the Apollo Moon landing hardware, as well as the CSM, tremendously.
Forty-five years later, as analysis of the lunar samples continues, the tremendous geology performed by Scott and Irwin continues to shed light on the origin of the Moon and of the Solar System.
Collin Skocik
Collin R. Skocik has been captivated by space flight since the maiden flight of space shuttle Columbia in April of 1981. He frequently attends events hosted by the Astronaut Scholarship Foundation, and has met many astronauts in his experiences at Kennedy Space Center. He is a prolific author of science fiction as well as science and space-related articles. In addition to the Voyage Into the Unknown series, he has also written the short story collection The Future Lives!, the science fiction novel Dreams of the Stars, and the disaster novel The Sunburst Fire. His first print sale was Asteroid Eternia in Encounters magazine. When he is not writing, he provides closed-captioning for the hearing impaired. He lives in Atlantic Beach, Florida.
