Apollo Mission To Tycho Crater

Out of the seven programmed Surveyor spacecraft launched to the lunar surface between 1966 and 1968, only the last, Surveyor 7, strived for a target selected mainly for its scientific significance. Surveyors 2 and 4 failed their missions, while Surveyors 1, 3, 5, and 6 soft-landed at even mare. It is a basalt plain, sites in the Apollo Zone. The near-equatorial band is readily accessible to piloted Apollo LM or the Lunar Module spacecraft

The thriving Apollo Zone Surveyors were utilized to perform valuable scientific examinations, but their main goal was to image their landing sites and analyze soil bearing strength to help ensure mission planners that the Moon terrain was stable and smooth enough to allow Apollo astronauts to land safely.

The Surveyor 7 Aimed For Tycho Crater

The Surveyor 7 aimed for the steep northern flank of Tycho crater, one of the most notable features on the Moon’s Earth-facing nearside hemisphere. 

And the 85-kilometer-wide asteroid impact, centered at 43° south latitude in densely cratered highlands terrain, is enclosed by an extensive arrangement of bright rays best seen when the Moon is full. 

Furthermore, the rays are made up of debris shattered out when Tycho crater was formed about 110 million years ago. Some stretch for 1500 kilometers across the Moon’s face.

The Surveyor 7 took off from Cape Kennedy on top of an Atlas-Centaur rocket on 7 January 1968. It touched down on 10 January at 40.9° south latitude, 11.4° west longitude. It was just 2.5 kilometers from its designated target and 30 kilometers from Tycho’s crater rim, on the ejecta blanket encircling the Tycho crater. 

And, less than an hour after landing on the lunar surface, the three-legged solar-powered lander delivered the first of more than 21,000 pictures it would beam to Earth. 

And, some of these were stereo pairs, allowing scientists to accurately determine the many different rocks and boulders noticeable in the field of view of the Surveyor 7’s scanning camera. 

Furthermore, other photographs were compiled into panoramic photomosaics that display Moon’s landscape features up to 13 kilometers away from the spacecraft.


Picture showing Tycho crater and its ejecta blanket. Also, Surveyor 7 landing site as imaged by NASA's Lunar Reconnaissance Orbiter (LRO).  Credit: NASA.

The Holy Grail of The 1960s Moon Exploration

So, amongst the hallmarks most intriguing to Moon scientists were so-called lakes of almost dark material. They occupied in depressions and had practically flat surfaces. And in numerous cases, these small dark plains were carved by branching and curving trenches. Furthermore, some scientists described the lakes as signs of new volcanism on the lunar surface, the “holy grail” of the 1960s Moon exploration.

And, besides its camera, the Surveyor 7 brought an alpha-scattering apparatus for determining the configuration of lunar soil and Moonrocks and an arm-mounted digger. 

So, at first, the alpha-scattering gear failed to deploy, but flight controllers back on Earth were capable of using the digger to push it down into contact with the Moon’s surface. 

And they later adopted the digger to position the alpha-scatterer on a Moonrock, and in a ditch, the digger had excavated. They discovered that lunar dirt at Surveyor 7’s landing place is more abundant in aluminum than that of the mare sites that the other Surveyors had visited.


Image showing a photomosaic of lunar panorama near the Tycho crater taken by Surveyor 7. The hills on the center horizon are about eight miles away from the spacecraft. Credit: NASA.
Image showing a photomosaic of lunar panorama near the Tycho crater taken by Surveyor 7. The hills on the center horizon are about eight miles away from the spacecraft.
Credit: NASA.

Tycho Crater Impact Had Shattered Several Kilometers

Furthermore, the controllers were not capable of placing the alpha-scatterer in contact with rocks on a low ridge near the Surveyor 7, some of which, scientists concluded, the Tycho crater impact had shattered from several kilometers beneath the lunar surface. 

So, they were far exceeding the digger’s 1.52-meter maximum range. Neither were they capable of moving the instrument to the location of the dark material of the lakes. And the nearest of which lay about a kilometer from the lunar lander. 

Meanwhile, the Surveyor 7 stopped to function on 21 February 1968, much was known of its complex landing site, but much else continued to be mysterious.

The tantalizing variety of rocks and the lakes near Surveyor 7 made some Moon scientists call for an Apollo mission to the section. It was far outside the Apollo’s Zone but could be reached at specific times of the year if Apollo mission rules were loosened.


Picture showing Apollo 11 lunar module pilot Buzz Aldrin during a moonwalk on NASA's historic first manned lunar landing mission in July 1969. Credit: NASA.
Picture showing Apollo 11 lunar module pilot Buzz Aldrin during a moonwalk on NASA’s historic first manned lunar landing mission in July 1969. Credit: NASA.

Apollo Tycho Mission

So, in August 1969, less than a month after NASA’s Apollo 11 moon mission, the first manned moon landing, (USGS) or the U.S. Geological Survey scientists worked with Bellcomm. It was NASA’s Apollo planning contractor, to design the surface portion of an Apollo Tycho mission. 

Furthermore, the Bellcomm/USGS team’s mission would begin with a pinpoint Lunar Module landing about a kilometer southeast of Surveyor 7. The Lunar Module’s descent stage would provide enough propellants so that, if the spacecraft slipped off course, then the Apollo mission’s Commander could take control of the Lunar Module computer and guide it up to about half a kilometer toward the selected touchdown point.

And on the basis of the Surveyor 7 and Lunar Orbiter V pictures, the NASA/Bellcomm team decided that the Tycho site was too rocky and rough for a lunar rover. 

So they suggested instead that the two Apollo crewmembers explore on foot inside a radius of operations of around 2.5 kilometers centered on their Lunar Module. 

Tycho Landing Site

Recommended new constant volume hard suits more robust and more flexible than the fabric Apollo spacesuits would, they expected, make possible quick geologic traverses in rugged terrain. 

The spacesuits would allow the astronauts to operate on the lunar surface for up to seven hours at a time. And the astronauts would spend 54 hours at the Tycho landing site. Or around twice as long as the Apollo 11 crew had spent on the Sea of Tranquillity, giving enough time for three seven-hour traverses.

During Traverse I, the Bellcomm/USGS team intended that one of the crew would deploy an ALSEP or an Apollo Lunar Scientific Experiment Package approximately 1.1 kilometers east of the Lunar Module. The Apollo Lunar Scientific Experiment Package or the ALSEP would incorporate a passive seismometer. 

So, in addition to installing a far southern station in the Apollo seismometer network, the device would exploit naturally occurring asteroid impacts and moonquakes to enable the study of Tycho’s subsurface structure. 


Photo of Tycho Crater and the Surveyor 7 taken by the Lunar Reconnaissance Orbitor(LRO). Credit: NASA.
Photo of Tycho Crater and the Surveyor 7 taken by the Lunar Reconnaissance Orbitor(LRO). Credit: NASA.

The Longest Tycho Mission Moonwalks

The Apollo Lunar Scientific Experiment Package or the ALSEP might also incorporate a heat flow experiment to help to learn if the area had experienced recent volcanism, a magnetometer, a laser retroreflector, and a gravimeter.

So, the other crewmember, meanwhile, would walk along the low ridge visible from the Surveyor 7 and gather the Moonrocks there. The two astronauts would then meet up and return to the vicinity of the Lunar Module, where they would get nearby “flow dome material.” Traverse I would total be around 3.5 kilometers.

And during Traverse II, the longest of the Tycho mission moonwalks, the Apollo crew would strike north to the shore of a notable kilometer-wide dark lake comprising branching trenches. 

The astronauts would sample and examine the lake and trenches, and then walk to a point 2.6 kilometers from the Lunar Module to collect “darkish radial rim material.” 

And on their way back to the Lunar Module, the crew would visit Surveyor 7 to get samples of Moon materials it had examined and to retrieve parts of the unmanned lander for engineering examination. Traverse II would total of 6.25 kilometers.

The Last Traverse of The Apollo Tycho Mission

So, the last Traverse of the Apollo Tycho mission would see the Apollo crew walk south 1.3 kilometers to examine another dark lake, and then go another 1.4 kilometers to inspect subsurface material exposed by a small fresh impact crater. 

The astronauts would then walk half a kilometer to a raised “flow levee” enclosed by “late smooth flow materials.” Traverse III would total of 5.25 kilometers. And in all, the Apollo crew would hike 15 kilometers and get between 100 and 200 pounds of samples throughout their three moonwalks.

Furthermore, the Bellcomm/USGS team recognized that the Tycho site included challenges beyond its position outside the Apollo Zone. And the place was enough undulating and rugged that the Apollo crew were likely to lose line-of-site contact with their Lunar Module’s radio antennas as they hiked around, causing them to lose radio contact momentarily with Earth. 

So, in addition, the Tycho site had not been imaged from orbit at adequately high resolution. If this were found to be a major limitation, the team suggested, then the Apollo Tycho mission could land much closer to Surveyor 7, where the surface had been well defined. 


A Surveyor 7 panorama picture, using newly digitized data. 
Credit: NASA.JPL-Caltech/University of Arizona Lunar and Planetary Laboratory/Gary Rennilson.
A Surveyor 7 panorama picture, using newly digitized data. 
Credit: NASA.JPL-Caltech/University of Arizona Lunar and Planetary Laboratory/Gary Rennilson.

Tycho Project

And this would, however, generate its own problems, the most grave of which would be to place much of the Traverse III circle beyond the planned 2.5-kilometer operational range of the Apollo Tycho mission’s moonwalks.

So, in early 1970, NASA’s engineers, never enthusiastic about the Tycho project, dismissed the region as being too hilly for an Apollo landing. And some scientists continued to sing the site’s praises. Furthermore, they pointed to the fact that the Surveyor 7 had successfully landed without the exact terminal guidance an Apollo astronaut could provide. So, they hoped that Apollo 16 or 17 might be redirected to Tycho. 

And so in the end, no Apollo Moon mission visited Tycho, leaving Surveyor 7 the honor of holding the highest-latitude landing site of any spacecraft that has soft-landed on the lunar surface.

The dark lakes seen near Tycho in the 1960s are recognized today to be patches of melt rock that flowed and was launched outward from Tycho crater during its explosive development and not to be signs of recent volcanic activity. 

Impact melt flows are observed inside and around many big young impact craters. Melt flow characteristics are rare near older craters due to the steady rain of micrometeoroids and very small asteroids that hit the Moon splinters them into moon-dust and boulders and slowly renders them indistinct.

That’s it, and I hope you enjoyed this short article. If you want to learn more about this fascinating crater, then go here and find out everything you need to know about Tycho crater. You will be amazed.

If you want to learn more about how to view the Moon from a telescope or a pair of binocular, then head over to this interesting article: How To See The Moon: Best Telescope Viewing Tips.

Do you want some more fascinating facts about our only satellite, then head over to this thought-provoking article: Moon Facts – Interesting & Strange Facts About The Moon.

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