Crash Sites. of Saturn Third. Stages and LM. Ascent Stages
The ultimate observational challenge (and extra-extra credit!) is sighting and identifying the impact sites of the Saturn IVB third stages and LM ascent modules. Not all impacted on the Moon. As with the Apollo landings sites themselves, the impact craters of the Saturn IVB and LM stages are not large enough to be viewed directly with backyard telescopes. The third stage impact craters are about 100 feet or so in diameter, far too small to be seen with Earthbound telescopes. The S-IVB and LM impact sites tended to be in the same general vicinity as the landings themselves, as seen in Fig. 12.1. Good luck in identifying these sites!
J. L. Chen, How to Find the Apollo Landing Sites,
The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-06456-7_12, © Springer International Publishing Switzerland 2014
Apollo 15 KM Impact
Apollo 17 LM Ascent Stage
Apollo 14 LM AscenDStage Apollo 12 Landing Site
Apollo 15 S-IVR Impact & Agollo irS-IVB. .
Apollo 13 S4VB
. Apollo 14 S-1VB – ^ * 2^-
Fig. 12.1 Locations of Saturn IVB and LM Ascent stage Impacts. Courtesy of the author
Fig. 12.2 LRO view of the Apollo 13 S-IVB Third Stage Impact Site. Photo courtesy ofNASA and Arizona State University
The Apollo 13 third stage Saturn-IVB was the first deliberately sent to impact the Moon. The spent S-IVB third stage separated from the Command/Service Module and later impacted the moon north of Mare Cognitum. From the tracking of the radio signals of the rocket, the impact locations on the moon and the impact times were fairly well known. Figure 12.2 was taken by the LRO in 2009.
At the time of the Apollo 13 mission, only the seismometer at Apollo 12 was available, which had been deployed 5 months earlier. The S-IVB impact occurred on April 14, 1970, at a distance of 135 km from that seismic station at longitude 332.11°, latitude -2.56°, elevation 1,166 m. The later Apollo missions all took advantage of their third stages by impacting them on the Moon. With an expanding network of seismometers with each subsequent mission, impacting the known size and weight of the S-IVB third stage served as a calibration tool for all the ALSEP seismometers. The impacts by the S-IVB stages represented unique calibration signals for the Apollo seismic station network, which operated on the lunar surface from 1969 to 1977. Since the rocket impacts occurred at known times and places, the seismic wave velocities, in particular those within the upper lunar crust could be measured directly.
Fig. 12.4 Apollo 14 S-IVB Impact crater taken by LRO. Photo courtesy of NASA and Arizona State University
Upon the return of the Apollo 14 crew to the CM Kitty Hawk, the ascent stage of Antares was sent to the surface of the Moon to provide seismic data. The ascent stage of Lunar Module Antares impacted the Moon on February 6, 7:45 PM EST, at longitude 3.42° S latitude 19.67° W. Both the Apollo 12 PSE and the newly setup Apollo 14 PSE recorded the Antares’s impact, which occurred between the two seismometers. The resulting impact rang for an hour-and-a-half, with both ASE setups recording the event. Antares’ descent stage and the mission’s other equipment remain at Fra Mauro at 3.65° S and 17.47° W.
With the precedent established with the Apollo 13 S-IVB third stage, the Apollo 14 Saturn third stage was intentionally impacted onto the Moon at longitude 8.09° South and latitude 26.02° West. Again, this event provided data to the Apollo 12 PSE using a known size and mass.
The LM Falcon, after returning Apollo 15 astronauts Scott and Irwin to Endeavor, was jettisoned and impacted the Moon on August 3, 1971 at 26.36° N and 0.25° E. The empty discarded LM impacted west of the Apollo 15 ALSEP on the other side of valley, roughly 6 miles away from the Apollo 15 ALSEP deployment. Backyard observers viewing the Apollo 15 landing site need only shift their attention to westward to view the impact area of the Falcon.
The Saturn S-IVB third stage impacted the Moon on an earlier of July 29, 1971 at latitude 1.51° S and longitude 11.81° W. The Apollo 15 Saturn IVB impacted relatively near the Apollo 14 ALSEP. So viewing the Apollo 14 landing site will encompass to the east the impact site of the Apollo 15 third stage.
Both the Falcon and the S-IVB impacts were recorded by the PSE network which now included the PSE at the newly deployed Apollo 15 ALSEP at Hadley Rille and the Apennine Mountains.
Upon the return of the Apollo 16 crew to the CM Casper, the ascent stage of the LM Orion was intended to impact the Moon to provide seismic data. The ascent stage of LM Orion separated 24 April 1972, but a loss of attitude control rendered it out of control. It orbited the Moon for about a year. The Orion impact site on the Moon is unknown.
With the precedent established with the Apollo 13, 14, and 15 S-IVB third stages, the Apollo 16 Saturn third stage was intentionally impacted onto the Moon at longitude 1.3° North and latitude 23.8° West. This event provided data to the PSE network of created by Apollo 12, 14, 15 and 16 using a known size and mass.
Fig. 12.5 Apollo 17 Saturn IVB Third Stage after Jettison. Courtesy of NASA
Apollo 17’s LM Challenger ascent stage was sent crashing into the Moon, with the impact recorded by the ALSEP geophones left behind by Apollo 12, 14, 15, 16, and 17. NASA reported the ascent stage impacted the Moon at coordinates 19.96 N, 30.50E at 1:50 EST on 15 Dec 1972.
The spent Saturn IVB third stage for Apollo 17 impacted the lunar surface at 4.21S latitude, 12.31 W longitude at 3:32:42 pm EST on 10 Dec 1972.
As an additional note, the LM that did not land on the Moon from Apollo 10, called Snoopy, is lost in heliocentric orbit and efforts are underway to re-acquire it. British amateur astronomer Nick Howes embarked on a mission to find Snoopy. He’s looking for Apollo 10’s lunar module Snoopy, which is believed to be in an orbit around the sun, and is the only intact lunar module used operationally from the Apollo program. Howes is using a blink comparator, a machine that allows astronomers to rapidly shift back and forth between two images of the same part of the sky taken days or weeks apart. Movement of Snoopy can be detected by a change in position of an image against the background of stationary stars. Blink comparators used to be a manual devices, alternately shining a light behind two different images; modern astronomers have the luxury of computer software that shifts between images for them. Historically, a blink comparator is how Clyde Tombaugh found Pluto, painstakingly and manually flipping between two images at a time at the Lowell observatory in Flagstaff, Arizona. This technique is also how Mike Brown found the trans-Neptunian object Eris, which ultimately lead to Pluto being demoted from planet to a dwarf planet.
After Apollo 10 completed its successful rendezvous in lunar orbit, Stafford and Cernan transferred from Snoopy back into CM Charlie Brown. With all three men settled in their return spacecraft, they closed the hatch between the LM and CSM and separated, sending the LM Snoopy into deep space. The craft had no purpose beyond the dry run for a landing and like all lunar modules wasn’t equipped to come back to Earth. Mission control fired Snoopy’s ascent engine for 239 seconds to full depletion, using up all of its available fuel. This depletion firing sent the lunar module into an orbit around the Sun. The crew watched Snoopy gain speed as it disappeared into the distance.
With Snoopy’s portion of the mission complete, Stafford, Cernan, and Young went back to tracking landmarks on the moon’s surface. Their survey lasted 31 lunar orbits, after which they fired CSM Charlie Brown main engine for the return to Earth.
Neither the crew nor NASA paid attention to Snoopy’s fate after the jettison. NASA does, however, know where and when the LM separated and how fast the spacecraft was going. With this data, Howes can calculate its rough orbit and effectively shrink the area where the hunt for Snoopy will take place. The search for Snoopy will be difficult, but with enough photographic data and an approximate area to search, and a little luck that the lost LM will reflect enough light into the telescopic CCD chips to register, Snoopy may be found.