LUNAR EXPLORATION CONCLUDED

Apollo 17: The Close of an Era

Following completion of Apollo 15, with 16 in the planning stages and
only one mission remaining after that, one scientist expected that the
process of choosing a site for the last flight would be "a dilly of
an affair."72 Perhaps with that
thought in mind, Rocco Petrone, Apollo program director at NASA
Headquarters, started the procedure early, in October of 1971. After a
site evaluation document had been circulated among selected interested
scientists for their critique and response, an ad hoc site evaluation
committee would meet no later than December 30 to consider site
proposals and make recommendations to the Apollo Site Selection Board in
early 1972.73

Actually, site selection for Apollo 17 was not as difficult as might
have been expected, considering that it was the last chance for many
years to obtain material and data from the moon. Preliminary review of
possible sites produced a clear consensus of objectives for Apollo 17:
to investigate the pre-Imbrian highlands as far as possible from the
Imbrium basin; to sample "young" volcanics; to obtain
photographic and remote-sensor coverage of areas not previously
investigated; and to provide the best coverage for the new traverse
geophysics experiments that were to go along. Application of all these
considerations reduced the interesting sites to three: Taurus-Littrow, a
region on the southeastern rim of Mare Serenitatis; Gassendi, a large
crater on the northern rim of Mare Humorum; and (ranking a distant
third) Alphonsus, previously considered as an alternative to the
Descartes site. Of these three, the ad hoc site evaluation committee
concluded that Taurus-Littrow was the best. It was a two-objective site
(highlands and young volcanic material); it offered a reasonable
contingency for a walking mission in case the lunar rover should fail;
and it would provide the greatest amount of new information from the
orbital sensors in the service module.74

Operational considerations, taken up at the February meeting of the site
selection board, gave no site a clear advantage. Problems existed at all
three, although Alphonsus, already well studied, was acceptable. At
Gassendi there was a good chance that the astronauts would not be able
to get to their prime objective if they had to land beyond the nominal
3-sigma ellipse. For Taurus-Littrow, detailed studies at first indicated
that under "worst-case" conditions the site was unsuitable;
the 3-sigma ellipse could not be fitted into it. When trajectory
designers were urged to reconsider their calculations in light of the
results of Apollo 15, however, they produced some less conservative
numbers and the site was acceptable. With operational considerations out
of the way, the board picked Taurus-Littrow because of its greater
scientific potential.75

The Taurus-Littrow site was a flat-floored valley some 7 kilometers (4.3
miles) wide, a dark, bay-like indentation in the broken mountain chain
on the eastern edge of Mare Serenitatis, at 20 degrees 10 minutes north
latitude, 30 degrees 46 minutes east longitude. Bounded on three sides
by high mountain massifs, the valley contained numerous craters of
possible volcanic origin, as Al Worden had noted from orbit on Apollo
15.76

Premission data from the landing site indicated it to be geologically
complex. Rock types appeared to vary in age, composition, and probable
origin, and the mountains displayed structural features that might be
correlated with several major landforming events. The valley floor on
which Apollo 17 was to land appeared to be volcanic and thus might have
originated deep within the moon. A landslide intruded on one side of the
valley floor, and boulder tracks down the mountainsides added to
scientists' interest in the site.77

Until early 1971 Apollo 17 had been scheduled for June 1972; in February
the launch schedule was revised and both Apollo 16 and 17 were moved
forward, to March and December 1972, respectively.78 The new launch date for Apollo 17 required one
more launch constraint to be lifted, because Taurus-Littrow was not
accessible by translunar injection (departure of the spacecraft and
S-IVB from the earth parking orbit) over the Pacific Ocean. Early in the
program Pacific injection was adopted as the rule, since the alternative
- injection over the Atlantic - required a night launch at some times of
the year. Although Atlantic injection offered an economy in fuel and
thus an increase in allowable payload, the potential problems incident
to a night launch (see Chapter 6) tipped the scales.79 By the time the site selection board met in
February 1972, however, "the bullet had been bitten on night
launches"80; experience had made
those problems much less worrisome.

So it was that Apollo 17 was scheduled to leave the Cape at 9:38 p.m.
EST on December 6, 1972.81 From August
8, when the launch vehicle was moved to the pad, preparations went well.
Some minor hardware problems cropped up but were handled without
delaying the schedule. Launch day was bright and warm; the temperature
was in the mid-80s at midafternoon. All looked well for the last Apollo
mission until 30 seconds before launch, when the automatic sequencer -
the oldest and most reliable piece of automation at the launch complex -
shut the system down. The first launch delay in the Apollo program
caused by failure of equipment amounted to 2 hours and 40 minutes while
Cape and Marshall Space Flight Center engineers worked around the
malfunction. At 12:33 a.m. Eastern Standard Time on December 7, command
module America and lunar module Challenger
were off for Taurus-Littrow.82
Flight controllers made up the lost time during the translunar coast.83

America and Challenger entered lunar orbit on
schedule and all preparations for landing went smoothly. After the two
spacecraft separated, Cernan and Schmitt took a spectacular photograph
of their landing site. Three hours later Cernan powered up
Challenger for its descent. It touched down within 200
meters (650 feet) of its targeted landing point amid a field of craters
at 3: 15 p.m. EST on December 11.84

For the next 75 hours Cernan and Schmitt conducted the longest, and in
many ways the most productive, lunar exploration of the Apollo program.
During three trips from their base they laid out the surface
experiments, drove the lunar rover about 36 kilometers (22 miles) in
all, ranging as far as 7.37 kilometers (4.5 miles) from
Challenger, and collected roughly 243 pounds (110
kilograms, of soil and rock samples along with more than 2,000
documentation photographs.85

Like their predecessors, Cernan and Schmitt were somewhat constrained by
the preplanned sequence of activity. Still, before they left the lunar
module and while unloading the Rover and the surface experiments,
Schmitt found time to give Houston's back-room scientists both large-
and small-scale descriptions of the landing area and the surface under
his feet.86 Schmitt found the
environment in the landing area "superb" for observation: the
lighting was excellent and the rock surfaces generally clean, and he
found little difficulty in distinguishing mineralogical and textural
differences. For the most part he based his decisions on taking samples
on visually detectable differences or similarities.87

Besides collecting and documenting samples, on their traverses the
explorers laid out explosive charges for a seismic profiling experiment
(the charges would be set off after they left), took readings on a
portable gravity meter at various points along the route, and set up an
instrument to measure electrical properties of the lunar surface. At the
site for the surface experiments package they drilled two 2.54-meter
(8.3-foot) holes for heat-flow sensors, took a deep core sample, and set
up the geophones (detectors) for the seismic profiling experiment.88 The first excursion was largely taken
up by these chores.

After an overnight rest and a discussion with Houston concerning plans
for sampling, Cernan and Schmitt set out on their second trip to collect
specimens from boulders along the lower slopes of the South Massif and
to sample the lighter-colored soil that overlay the western part of the
valley. It was a long trip - an hour by rover to the first major
sampling stop - and would stretch their life-support systems almost to
the limit. The last couple of kilometers up the slope taxed the rover,
too, but it brought them to their objective in fine style. Schmitt took
samples from three boulders which, as best he could tell, had come from
layers visible farther up the South Massif.89

The obviously interesting features of their first site prompted Houston
to lengthen their stay there and cut some time from later stops. On
their way back they stopped to take an unscheduled reading on the
traverse gravimeter and sampled soil at a couple of crater rims, one of
which drew considerable attention. During routine examination of the
surface around the crater called "Shorty," Schmitt suddenly
called out, "Oh, hey - wait a minute - . . . There is orange
soil!" Cernan confirmed it. "He's not going out of his mind.
It really is." While looking for the limits of the orange deposit,
Schmitt remarked, "if there ever was something that looked like
fumarole alteration, this is it."90 He was excited because orange soil
(characteristic of oxidized iron, at least on earth) indicated volcanic
activity, probably recent, a feature not previously discovered on the
moon. While Houston kept reminding them they were almost at the limits
of their walk-back capability - time was running out - they dug a
trench, took a core sample and several scoop samples, and took
photographs. Then they mounted the rover to head back to
Challenger. Schmitt talked about his discovery all the way
back.91

The last sampling trip of the Apollo program was a traverse to the foot
of the North Massif, where they found two large boulders that had
obviously rolled down from outcrops higher on the mountain; their tracks
were visible in the soft soil. After covering 12 kilometers (7.5 miles)
and picking up 63 samples (137 pounds, 62 kilograms), Cernan and Schmitt
returned to the lunar module.92 Schmitt
picked up a symbolic rock sample in honor of a group of foreign students
touring the United States; it would be divided up to provide samples for
each country represented. Then Ceman unveiled a plaque on
Challenger's

This is our commemoration that will be here until
someone like us, until some of you who are out there, who are the
promise of the future, come back to read it again and to further the
exploration and the meaning of Apollo.

He then parked the rover at a spot where its television camera could
watch their takeoff, and Apollo's last two explorers finished their last
tasks on the moon. Cernan closed out the surface activity with the
comment that "I believe history will record that America's
challenge of today has forged man's destiny of tomorrow."93 Then they packed up their samples, discarded
the tools they would no longer need, and climbed back into
Challenger.94

Next day, December 14, they blasted off to join America in
lunar orbit. As television audiences on earth watched, the rover TV
camera, directed from Houston, followed their ascent stage until it was
out of sight, then slowly scanned the now-deserted lunar surface.95 The awareness that no living person was
around made the scene all the more impressive. It was almost possible to
hear the silence.

After hooking up with the moon-circling command module, Schmitt and
Cernan transferred their samples and data. America still
had a day's work to do, completing the photographic and remote-sensing
work that Ron Evans had been doing while his crewmates were on the
surface. Their work completed, the crew of Apollo 17 left the moon with
a blast from their service propulsion engine at 8:42 p.m. EST on
December 16. A routine transearth coast brought them back to a landing
about 300 kilometers (200 miles) east of Pago Pago at 2:25 p.m. EST on
December 19, 1972.96 Apollo's
exploration of the moon, "one of the most ambitious and successful
endeavors of man,"97 was over.

While scientists awaited the samples from Taurus-Littrow, editorial
writers offered varying evaluations of the lunar exploration project.
Perhaps the bitterest farewell to Apollo was expressed by William Hines,
syndicated Chicago Sun-Times columnist, who had opposed the
project from the start: "And now, thank God, the whole crazy
business is over."98 The
Christian Science Monitor cautioned that "Such
technological feats as going to the moon do not absolve people of
responsibilities on earth."99 The
New York Times decided that "Man's entire perspective
on the universe and on his place in it has been radically changed. Man
evolved on the earth, but he is no longer chained to it."100Time magazine noted that after
the magnificent effort to develop the machines and the techniques to go
to the moon, Americans lost the will and the vision to press on.
Apollo's detractors, said Time, were

prisoners of limited vision who cannot comprehend, or
do not care, that Neil Armstrong's step in the lunar dust will be well
remembered when most of today's burning issues have become mere
footnotes to history.101

86. MSC, "Apollo 17 Technical
Air-to-Ground Voice Transcription," Dec. 1972 (hereinafter cited as
"17 Air-to-Ground"), tape 76A, pp. 4-8, tape 77A, p. 34,
39-41. This transcript is paginated by tape number; tape numbers run
sequentially in three series, A, B, and undesignated, corresponding to
communication with the lunar module (A) and the command module (B) when
the two were separated, and with the command module when all three
crewmen were aboard before and after separation (undesignated).

98. William Hines, "End of a crazy
business," Chicago Sun-Times, Dec. 21, 1972. Hines
went on to castigate the Apollo project from concept to execution, and
concluded by quoting Max Born, Nobel laureate in physics, who had said
in 1958 as the "space race" began, "Intellect
distinguishes the possible from the impossible; reason distinguishes the
sensible from the senseless. Spaceflight is a triumph of intellect and a
tragic failure of reason."