Posted by KeighleyAstro on Jun 24, 2023 in Main |

It was a packed attendance at the June meeting of Keighley Astronomical society on Thursday 22nd. The members were drawn to a presentation by the popular guest speaker Mr Peter Rea FRAS from Cleethorpes and district Astronomical society. The subject of his return visit us was ‘How it began’ – The origins of Lunar exploration 1958 to 1976.

Mr Rea commenced with an image painted in the 1940’s by the artist Chesley Bonestel, who was influential in popularising the idea of future exploration of the Moon and beyond. He explained that the early depictions of the lunar surface were of tall jagged peaks and rough rocks. Based on the knowledge at the time that there was no water or atmosphere on the Moon to erode and weather down and smooth such features. When Man arrived at the Moon scientists were surprised to fine that the surface of the Moon was smooth and worn. It had another weathering feature; micro meteorite particles.

Both the Soviet Union and the United States of America had involved themselves in a Cold War race to be the first nation to land human manned missions to the Moon. Both nations had to prepare the ground for those landings and therefore a much greater understanding of the lunar surface was required. They needed to test the surface of the Moon to establish if it was safe to land successfully on the lunar surface, and where to land on the Moon. This work could not been done with Earth based telescopes and the detail obtained was not good enough. Exploratory missions to the Moon where therefore required.

The next chapter in Mr Rea’s presentation was an interesting graph. Which showed the number of missions to the Moon each nation undertook between 1958 and 1976.

Luna Competing United States programmes
Type First attempt Attempts First success Successes Rate First attempt Attempts First success Successes Rate
Impactor 23 Sep 1958 6 Luna 2Sep 13, 1959 1 16.7% Ranger 123 Aug 1961 9 Ranger 731 July 1964 3 33.3%
Flyby Luna 36 Oct 1959 3 Luna 3 1 33.3% Pioneer 36 Dec 1958 2 Pioneer 46 Mar 1959 1 50.0%
Soft lander 4 Jan 1963 13 Luna 93 Feb 1966 2 15.4% Surveyor 12 Jun 1966 7 Surveyor 1 5 71.4%
Orbiter 1 Mar 1966 8 Luna 103 Apr 1966 6 75.0% Pioneer 017 Aug 1958 12 Lunar Orbiter 118 Aug 1966 5 41.7%
Rover 19 Feb 1969 3 Luna 1717 Nov 1970 2 66.7% Apollo 1531 July 1971 3 Apollo 15 3 100.0%
Sample return 14 Jun 1969 11 Luna 1624 Sep, 1970 3 27.3% Apollo 1124 Jul 1969 7 Apollo 11 6 85.7%

Total 44 15 34.1% Total 40 24 60.0%

There was a clear and sharpe increase in American Missions from 1965 until the First manned landing in July 1969. The number of Soviet moon missions continued well after 1969, because by 1966 is was becoming clear the United States had gained a lead over the Soviet Union and that America was in course to land men on the Moon first. The graph clearly showed how the Soviet Union tried to match the American manned moon landings with their own unmanned missions. In 1969 alone (the year of the landing of Apollo 11) there were nine Soviet missions to the Moon. The Soviet goal was to obtain and return samples of the Moon’s regolith by robotic means before the Americans would be doing with the Manned Apollo missions. However the Soviets were unsuccessful in the goal and Apollo 11 brought the first samples to Earth from the Moon.

Mr Rea then moved on to the naming of the individual missions to the Moon. The assistant director for the American Lunar and planetary exploration programme was Edgar Cortright.

He joined the newly formed NASA agency (successor to the NACA) as a founding member in 1958 and worked at NASA Headquarters in Washington D.C. where he was Chief of Advanced Technology (1958–1959); Assistant Director for Lunar and Planetary Programs, Office of Space Flight Programs, (1960–61); Deputy Director for Space Science and Applications (1961–1963); Deputy Associate Administrator for Space Science and Applications (1963–1968); and Deputy Associate Administrator, Office of Manned Space Flight, (1968). Edgar Cortright created the naming system for the individual mission names that we remember today.

Names such as :-

Pioneer

Ranger

Surveyor

Prospector

The different type mission programmes consisted of :-

‘Flybys’ – A flyby is the simplest lunar spacecraft, requiring neither a propulsion device for slowing, nor a guidance system sensitive enough to hit the Moon. Its function is to transmit photographs back to Earth. These were the ‘Pioneer ‘ missions.

‘Impactors’ – Impactor spacecraft are designed to hit the near side of the Moon. These were the ‘Ranger’ missions.

‘Soft Landers’ – Soft landers require rocket propulsion to slow their speed sufficiently to prevent the craft’s destruction. They can continue to transmit pictures from the surface, and possibly dig into the lunar soil or return other information about the lunar environment. These were the ‘Surveyor’ missions.

‘Lunar orbiters’ – Orbiter spacecraft require less thrust and propellant than landers, but still require enough to achieve lunar orbit insertion. These mission were simply called ‘Lunar Orbiter.

The Soviet Luna Programme

All the Soviet missions were called ‘Luna’ right up to number 24 in 1976.

‘Impactors’ – Luna 1 (January 1959) missed its intended impact with the Moon and became the first spacecraft to escape the Earth-Moon system. Luna 2 (September 1959) mission successfully hit the Moon’s surface, becoming the first man-made object to reach the Moon. This was Luna’s only impact success out of six tries from September 1958 to September 1959.

‘Flybys’ – .Luna 3 (October 1959) rounded the Moon later that year, and returned the first photographs of its far side, which can never be seen from Earth. This was Luna’s only successful flyby, out of three tries from October 1959 to April 1960.

‘Soft Landers’ – Luna program landers had the generic designation of Ye-6 (or E-6 depending on transliteration from Russian). Two successful soft landings were achieved out of thirteen attempts from January 1963 to December 1966.
Luna 9 (E-6 No.13) became the first probe to achieve a soft landing on another planetary body in February 1966. It transmitted five black and white stereoscopic circular panoramas, which were the first close-up shots of the lunar surface. Only two out of the 13 soft landers dispatched were successful.

‘Lunar orbiters’ – Luna 10 (March 1966) became the first artificial satellite of the Moon. Luna flew six successful orbiters out of eight attempts from March 1966 to May 1974.

‘Robotic Rovers’ – This was something the Americans never achieved on the Moon. More sophisticated soft lander craft can deploy wheeled vehicles to explore a wider area of the lunar surface than the immediate landing site. The first attempted Lunokhod failed in February 1969. Luna 17 (November 1970) and Luna 21 (January 1973) carried ‘Lunokhod’ vehicles, which were the first robotic wheeled vehicles to explore the Moon’s terrain. Lunokhod 1 travelled 10.5 kilometres (6.5 miles) in 322 days and returned more than 20,000 television images and 206 high-resolution panoramas. Lunokhod 2 operated for about four months, covered 42 kilometres (26 miles) of terrain,[A third Lunokhod was built and intended for launch in 1977, but never flew due to lack of launchers and funding.

Mr Rea then displayed photos taken by. Lunokhod 1 taken in September 1971.

‘Sample return’ – More complex soft lander craft can robotically scoop up a small amount of lunar material, lift off from the surface, and return the material to Earth. Luna 16 (September 1970), Luna 20 (February 1972) and Luna 24 (August 1976), returned samples of lunar soil to Earth. A total of 301 g (10.6 oz) of soil sample was returned from the three missions.

Luna 15 (July 1969) flew at the same time as the Apollo 11 mission. Neil Armstrong and Buzz Aldrin had already performed the first crewed lunar landing when Luna 15 began its descent, and the spacecraft crashed into a mountain minutes later.

The American Lunar Programme

‘Flybys’ – ‘Pioneer’ – The Pioneer programs were two series of United States lunar and planetary space probes exploration. The first program, which ran from 1958 to 1960, unsuccessfully attempted to send spacecraft to orbit the Moon, successfully sent one spacecraft to fly by the Moon, and successfully sent one spacecraft to investigate interplanetary space between the orbits of Earth and Venus. None of the first nine missions were successful.

The second program, which ran from 1965 to 1992, sent four spacecraft to measure interplanetary space weather, two to explore Jupiter and Saturn, and two to explore Venus.

The two outer planet probes, Pioneer 10 and Pioneer 11, became the first two of five artificial objects to achieve the escape velocity that will allow them to leave the Solar System, and carried a golden plaque each depicting a man and a woman and information about the origin and the creators of the probes, in case any extra-terrestrials find them someday.

‘Impactors’ – Ranger – The Ranger programmes objective was to obtain the first close-up images of the surface of the Moon. The Ranger spacecraft were designed to take images of the lunar surface, transmitting those images to Earth until the spacecraft were destroyed upon impact. A series of mishaps, however, led to the failure of the first six flights. At one point, the program was called “shoot and hope”. Congress launched an investigation into “problems of management” at NASA Headquarters and the Jet propulsion laboratory after two reorganisations of the agencies.

Ranger 7 successfully returned images in July 1964, followed by two more successful missions.
Ranger was originally designed, beginning in 1959, in three distinct phases, called “blocks”. Each block had different mission objectives and progressively more advanced system design.
In February 1965, Ranger 8 swept an oblique course over the south of Oceanus Procellarum and Mare Nubium, to crash in Mare Tranquillitatis about 70 kilometers (43 miles) distant from where Apollo 11 would land 4½ years later. It garnered more than 7,000 images, covering a wider area and reinforcing the conclusions from Ranger 7.

About a month later, Ranger 9 came down in the 90-kilometer (56-mile) diameter crater Alphonsus. Its 5,800 images, nested concentrically and taking advantage of very low-level sunlight, provided strong confirmation of the crater-on-crater, gently rolling contours of the lunar surface.

Mr Rea explained that the great revelation that came from the images produced by the Ranger missions was it was not just large craters on the lunar surface but that the surface was nothing but craters from the very small to the extremely large.

‘Soft Landers’ – Surveyor – This programme ran from June 1966 through January 1968, sent seven robotic spacecraft to the surface of the Moon. Its primary goal was to demonstrate the feasibility of soft landings on the Moon. The Surveyor craft were the first American spacecraft to achieve soft landing on an extra-terrestrial body. The missions called for the craft to travel directly to the Moon on an impact trajectory, a journey that lasted 63 to 65 hours, and ended with a deceleration of just over three minutes to a soft landing.

The program was implemented by NASA’s Jet propulsion laboratory (JPL) to prepare for the Apollo programme, and started in 1960. JPL selected Hughes Aircraft in 1961 to develop the spacecraft system. The total cost of the Surveyor program was officially $469 million.

Five of the Surveyor craft successfully soft-landed on the Moon, including the first one. The other two failed: Surveyor 2 crashed at high velocity after a failed mid-course correction, and Surveyor 4 lost contact (possibly exploding) 2.5 minutes before its scheduled touch-down.

All seven spacecraft are still on the Moon; none of the missions included returning them to Earth. Some parts of Surveyor 3 were returned to Earth by the crew of Apollo 12, which landed near it in 1969. The camera from this craft is on display at the National Air and Space museum in Washington, DC.

Mr Rea explained the significance of these images on the Moon surface highlighted that craters and other obstacles were easier to be seen and identified when the sun was low and there were shadows formed. All later Apollo landings were undertaken during the lunar Sunrise with the lander approaching the landing site with the Sun behind it.

Mr Rea explained the significance of these images on the Moon surface highlighted that craters and other obstacles were easier to be seen and identified when the sun was low and there were shadows formed. All later Apollo landings were undertaken during the lunar Sunrise with the lander approaching the landing site with the Sun behind it.

The Lunar Orbiter program was a series of five missions launched from 1966 through 1967. Intended to help select the Apollo landing sites by mapping the Moon’s surface, they provided the first photographs from lunar orbit and photographed both the Moon and Earth.
All five missions were successful, and 99 percent of the lunar surface was mapped from photographs taken with a resolution of 60 meters (200 ft) or better. The first three missions were dedicated to imaging 20 potential crewed lunar landing sites, selected based on Earth-based observations.

These were flown at low-inclination orbits. The fourth and fifth missions were devoted to broader scientific objectives and were flown in high-altitude polar orbits. Lunar Orbiter 4 photographed the entire nearside and nine percent of the far side, and Lunar Orbiter 5 completed the far side coverage and acquired medium (20 m or 66 ft) and high (2 m or 6 ft 7 in) resolution images of 36 preselected areas.

Mr Rea explained that the images taken by the Luner orbiters used old fashioned photographic film which was them scanned by the equipment on the obiters and sent to the Earth. He explained that you can always identify a lunar orbiter photograph as it always has a horizontal banding caused in the process of sending the images back to NASA.

Over all during this time period from 1958 to 1976 the Soviet Union had a success rate of 35% for its Moon missions and the United States had a success rate of 43%.

Mr Rea ended his presentations by saying that all the American missions outlined in his presentations had to support the Apollo Moon landing missions. With them the First Men on the Moon in July 1969 would never have taken place.