When the Apollo lunar landing sites are plotted to approximate scale on maps of the USA and Europe it gives an idea of how human exploration barely scratched the Moon’s surface.
Our 6 short trips there between 1969 and 1972 were the greatest technological achievement in human history. It was a defining moment for our species – the only one to ever pilot itself away from planet Earth and set foot on our nearest satellite.
The 838 pounds of lunar rocks and soil that the Apollo astronauts brought home are still being sifted through and are still revealing secrets about the Moon, as well as the origins of the Earth and the solar system. The lunar rocks are much older than the samples generally found on Earth, and some contain geochemical components which have no known terrestrial counterpart.
More recent probes have shown that the Moon is not as ‘magnificently desolate’ as we first thought in 1969. In 2009 NASA deliberately smashed a probe into a large crater at the lunar south pole. The impact plume apparently kicked up the equivalent of “a dozen 2-gallon buckets” of water in the form of ice and vapour. Other probes have detected evidence of tons of water ice at the moon’s north pole and elsewhere across the surface.
Perhaps the next giant leap for mankind shouldn’t be Mars, but back to the Moon – this time with the materials to build a permanent base there.
The Apollo landing sites:
On 20 July 1969 Apollo 11 astronauts Neil Armstrong and Buzz Aldrin made history as the first human beings to land on the Moon. Their landing site was in the lava-plain named by astronomers in 1651 as the Sea of Tranquility (or Mare Tranquillitatis as the convention was to name lunar places in Latin). It was selected partly because it had been assessed as relatively flat and smooth. In the event, technical problems meant they landed 4 miles west of their intended target in a boulder-strewn area close to a 1000 feet long crater. The astronauts spent 2 hours 31 minutes walking the lunar surface at Tranquility Base before lifting off with 47.5 pounds of soil and rock samples. Tranquility Base has remained unvisited since then.
The Apollo 12 mission landed on 19 November 1969, on an area of the Ocean of Storms that had been visited earlier by several unmanned missions (consequently the region became the Mare Cognitum, or Known Sea). In fact, Apollo 12’s precision landing was within walking distance of the Surveyor 3 probe, which had landed on the Moon in April 1967 (this was the first – and so far only – occasion that humans have recovered a probe from another world).
The Apollo 14 mission landed on 5 February 1971 in the Fra Mauro Highlands, which had originally been the target of the ill-fated Apollo 13 mission. The Fra Mauro Highlands are named after the 50 mile-wide Fra Mauro Crater located there, and both features take their name from a 15th-century Italian monk and mapmaker. The hilly area was formed from debris from the impact which formed Mare Imbrium (or Sea of Showers); data from the mission has helped to age Mare Imbrium at around 4.25 billion years old. The mission’s achievements included the longest distance traversed by foot on the lunar surface.
Apollo 15 landed on 30 July 1971 in a lava plain known as Palus Putredinis (Marsh of Decay), which is bordered by the Montes Apenninus (a 15,000 foot mountain range named after the Apennine Mountains in Italy). The mission was the first to carry a lunar rover, a four-wheeled Jeep which enabled the astronauts to drive several miles away from the lunar lander. On one of their drives along the Apennine Front they found one of Apollo’s most famous lunar samples, the 4 billion year old Genesis Rock.
Apollo 16 was the first mission to land in the lunar highlands on 21 April 1972. The Descartes Highlands region was chosen to allow the gathering of geologically older lunar material than had previously been collected. The Moon’s contrasting bright and dark zones show the difference between the bright lunar highlands (called terrae from the Latin for Earth) and the darker plains (called maria from the Latin for sea). The highlands are older than the visible maria, and more heavily cratered. The site was also a considerable distance away from the other Apollo landing sites (except Apollo 11), which was an advantage for the network of geophysical instruments deployed on each mission after Apollo 11.
Apollo 17 touched down on the lunar surface on 11 December 1972. It landed in the Taurus-Littrow Valley, located in the Taurus mountain range. This ring of mountains was formed around 3.85 billion years ago when a large object impacted the Moon, forming Mare Serenitatis and pushing rock outward and upward. The site was selected to allow the crew to obtain samples of old highland material from the remnants of a landslide event that occurred on the south wall of the valley. Apollo 17 broke several records set by previous missions, including the longest total time engaged in activities on the lunar surface – over 22 hours, the largest distance covered in their lunar rover – over 22 miles, and the furthest distance travelled from the safety of the lunar module – 4.75 miles.
Before re-entering the lunar module for the final time, the Apollo 17 Commander Gene Cernan said:
“…I’m on the surface; and, as I take man’s last step from the surface, back home for some time to come – but we believe not too long into the future – I’d like to just say what I believe history will record. That America’s challenge of today has forged man’s destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind.”
Over 42 years later he remains the last human being to have walked on the Moon, and his crew were the last humans to have travelled beyond low Earth orbit.
Image sources: NASA and Google Earth