v0.2 - 25-04-2020
Moon landings during the space race
Earth's moon is a body that has no atmosphere. Therefore a parachute landing is by definition, impossible. These landings are quite complex as one needs a high amount of control over the rocket engines to perform a safe landing. This can be seen by the motor used on the Apollo Lunar Lander which could be throttled to between 10 and 60% of full thrust.
Luna Programme
Operator: Soviet space program
Target: Moon
Landing date: 1959-1976
Status: Retired
The Luna programme was a multi-billion two-decade-long programme that consisted of more than 40 launches, however, only 24 have official Luna numbers as the others failed to leave Earth's orbit. The programme achieved several "firsts", namely the first lunar impactor, the first lunar flyby, the first spacecraft to take a picture of the far side of the moon, the first soft landing, the first lunar orbiter, and lastly first circumlunar probe to return to earth. The programme was divided into 3 generations of spacecraft.
Luna 1-3
The first generation of spacecraft was Luna 1 through 3. Luna 1, intended as an impactor, missed the moon and was the first spacecraft to do a lunar flyby. Luna 1 released one kg of sodium gas in space making it visible and allowing it to be tracked by astronomers from the Earth. There was no propulsion on board and it was powered using mercury oxide batteries. It also discovered the existence of solar winds and the lack of a magnetic field on the moon. Luna 2 was similar to Luna 1 and was successful in impacting the moon. Luna 3 was a flyby mission that clicked 29 photos of the far side of the moon. Unfortunately, only 17 of those images could be transmitted back to Earth.
Luna 4-14
The second generation of spacecraft was Luna 4 through 14. Luna 4-8 were landers that failed at soft landing. Luna 8 completed the development of a star tracker and failed because a puncture in the airbag led to a landing failure. Luna 9 was the first successful lander on the moon. It also debunked the fear that the surface of the moon was too soft, and the lander would sink in.
Luna 10 was the first spacecraft to successfully orbit a planetary body other than Earth. The “Internationale” was broadcast from Luna 10 during its first orbit and played in front of the Twenty-third Congress of the Communist Party of the Soviet Union. Luna 11 was an orbiter who amongst other things tested the efficiency of lubricants for gear transmission in vacuum for future rover missions. Luna 13 was a lander which was very similar to Luna 9. It took panorama pictures that took 100 minutes to transfer each. Luna 14 was an orbiter to test communication systems in lunar orbit and earth and engineering test of gear transmission systems in a vacuum.
Luna 5-24
The third generations of spacecraft were Luna 15 through 24. Luna 15 was a sample return mission that took place at the same time as Apollo 11. It is suspected to be a last-ditch attempt at getting lunar samples back to Earth before the US. Unfortunately, the landing wasn't successful. Luna 16 was the first successful Soviet sample return mission. The lander had a drill and robotic arm to load the samples into the rocket. The spacecraft was able to drill to a depth of 35 cm before encountering hard rock. 101 grams of sample were returned to earth. There was no control system on the return rocket and there was only one burn to set it on the trajectory of Earth.
Luna 17 was the first successful rover mission by the Soviet Union. Rover Lunokhod 1 used solar cells for power, travelled more than 10 km and lasted 11 days. It sent over 20000 pictures and 200 panoramas. Luna 19 was the first third-generation lunar orbiter. Luna 20 was a sample return mission that sent back 30g of moon regolith. Luna 21 was the second successful rover mission that landed Lunokhod 2. It had a top speed of 2 km/hr and used polonium-210 as a heat source. It operated for 4 months and travelled 37 km. The Lunokhod retroreflector is still used for lasers ranging from Earth.
Luna 22 was an orbiter mission similar to Luna 19. It tested lubricants on different frictional surfaces and studied different coatings with varying reflective properties. Luna 23 was a sample return mission that landed successfully but the sample return apparatus didn’t work, so no samples were obtained. Luna 24 was a successful sample return mission. It landed only a few hundred meters from Luna 23 and sent 170.1 g of samples.
Luna 1
Picture of dark side of Moon taken by Luna 3
Luna 16
Lunokhod 1
Surveyor Programme
Operator: NASA
Target: Moon
Landing date: 1966-1981
Status: Retired
The Surveyor program was a NASA initiative that ran from June 1966 through January 19681. The program’s primary goal was to demonstrate the feasibility of soft landings on the Moon. This was a crucial step in preparing for the Apollo missions, which would eventually bring humans to the lunar surface.
Each Surveyor spacecraft travelled directly to the Moon on an impact trajectory, a journey that lasted 63 to 65 hours. The final part of the journey involved a deceleration of just over three minutes to achieve a soft landing. This was a significant achievement, as the Surveyor craft was the first American spacecraft to achieve soft landing on an extraterrestrial body.
Out of the seven robotic spacecraft sent to the Moon, five successfully soft-landed. These included Surveyor, the first U.S. spacecraft to make a true soft landing on the Moon. The other two, Surveyor 2 and Surveyor 4, unfortunately failed.
One of the significant achievements of the Surveyor program was the development of closed-loop terminal descent guidance and control systems. These systems were crucial for ensuring the spacecraft could navigate its way to the Moon and perform a soft landing. The systems had to be incredibly precise, as even minor errors could result in mission failure.
The Surveyor spacecraft were equipped with throttleable engines, another major engineering feat. These engines could adjust their thrust levels in response to commands from the guidance and control systems. This capability was vital for the deceleration phase of the lunar landing.
The Surveyor program also saw the development of radar systems required for determining the lander’s altitude and velocity. These radar systems provided real-time data to the guidance and control systems, enabling them to make necessary adjustments during the descent to the lunar surface.
Surveyor lander with Apollo 12 astronauts Pete Conrad and Alan Bean
Zond Programme
Operator: Soviet space program
Target: Moon
Landing date: 1964-1970
Status: Retired
Zond program was two distinct series of spacecraft with the goal of exploration of nearby planets and robotic circumlunar loop flights and recovery.
Zond 1-3
Zond 1-3 used the 3MV planetary probe. Zond 1 and 2 were sent on Venus and Mars flyby respectively. However, both missions lost communication before they reached near the planets. Zond 3 was sent on a lunar flyby mission and was the second spacecraft to click a picture of the far side of the moon. It continued to a trajectory of Mars and eventually lost communication.
Zond 4-8
Zond 4-8 were the soviet test flights during the moon race. They used the Soyuz L1 spacecraft. These spacecraft travelled in a free-return trajectory around the moon without going into lunar orbit. They were designed to potentially carry two astronauts.
Zond 4 was a test mission launched away from the moon and was supposed to make a skip re-entry. However, the separation mechanism of the re-entry module and service module failed which resulted in the trigger of the self-destruct mechanism at an altitude of 10-15 km/s.
Zond 5 improved on its predecessor and was the first spacecraft to travel around the moon and land safely on Early. Zond 5 had a payload of few animals such as tortoises, flies, worms, etc who returned alive. Additionally, it also carried a full-sized human mannequin with radiation detectors. Due to a failure of attitude sensors, the spacecraft performed a water landing in the Indian Ocean as opposed to a planned land landing.
Zond 6-8 were uncrewed test missions aimed at improving the reliability and circled the moon and landed on earth. Zond 6 aimed at land landing but suffered from cabin depressurisation. This depressurisation led to electronics malfunction and the spacecraft prematurely jettisoned the parachutes and fired the soft-landing thrusters 5.3 kms above the surface. While the capsule crashed, it was still recovered in a one piece. Zond 6 was a precursor to crewed missions, but a range of technical problems prevented that from happening.
Zond 7 was the first in the series to perform a successful land landing and Zond 8 performed a successful sea landing. Unfortunately, these were not followed by crewed missions. Zond missions also carried scientific payloads and gathered data on cosmic rays, solar winds, radio emissions and micrometeoroids.
Ranger Programme
Operator: NASA
Target: Moon
Landing date: 1961-1965
Status: Retired
The Ranger program often referred as the “Shoot and Hope” program in its early years were a series of spacecraft launched to advance American space technology and map the surface of the moon. The program was divided into three key blocks. The spacecrafts within the three blocks were nearly identical to each other. The first 6 mission of the Ranger program failed and missions 7,8 and 9 succeeded. The Ranger spacecrafts were launched on the Atlas rockets and used the Agena second stage to propel them towards the moon. All the missions in the Ranger program were designed to be impactors due to launcher limitations.
Ranger Block 1
Ranger 1 & 2 were meant to test the operations and reliability of the different subsystems. They both failed in low earth orbit after stabilisation issues.
Ranger Block 2
The second block of Ranger spacecraft had a lot more scientific instruments than the first block such as Gamma Ray Spectrometer, TV Camera, Radio Altimeter, etc. It also had a Lunar Impacting Capsule which was meant to survive a 100 mile/hr impact and make measurements for 30 days. The capsule has a seismometer to measure moonquakes. The instrument was housed around two layers of liquids, liquid Freon and water respectively. Additionally, the liquids were housed inside a Balsa wood shell. The iconic stripe paint pattern was chosen to minimise thermal variance in the instrument environment.
Ranger 3 missed the moon by 38,800 km and is still orbiting the Sun. Ranger 4 had a perfect launch, but spacecraft communications got disabled. The capsule impacted the lunar far side. Ranger 5 missed the moon by 725 km
Ranger 5
Ranger Block 3
After the failure of the first two blocks, there was intense pressure to get things working. Therefore, redundancy was added in most key systems such as Power, Communications and TV Cameras. There were 6 cameras with different lenses on board block 3 spacecraft. The cameras fired one after the other to prevent excessive heat and could capture one image every 10 seconds. The communication equipment was designed to send pictures up to 0.2 second before impact.
Ranger 6 impacted the moon, but cameras failed. Ranger 7 was the first successful mission of the program and sent close-up pictures of the lunar surface in July 1, 1964. Ranger 7 had a successful impact and sent over 4000 pictures. Ranger 8 also had a successful impact and sent over 7000 pictures. Ranger 8 had a successful impact and sent over 5800 pictures
