To learn lunar landing techniques, astronauts practiced in the Lunar Landing Research Vehicle (LLRV), a flying vehicle that simulated the Lunar Module on earth. A 200-foot-tall, 400-foot-long gantry structure was constructed at NASA Langley Research Center; the LLRV was suspended in this structure from a crane, and "piloted" by moving the crane. (The facility is now known as the Impact Dynamics Research Facility, and is used for aircraft crash tests.)
Early configurations of the LEM included a forward docking port, initially it was believed the LEM crew would be active in the docking with the CSM. Early designs included large curved windows. Configuration freeze did not start until April 1963 when the ascent and descent engine design was decided. In addition to Rocketdyne a parallel program for the descent engine was ordered from Space Technology Laboratories in July 1963, and by January 1965 the Rocketdyne contract was cancelled. As the program continued there were numerous redesigns to save weight (including "Operation Scrape"), improve safety, and fix problems. For example initially the module was to be powered by fuel cells, built by Pratt and Whitney but in March 1965 they were paid off in favor of an all battery design.
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A Lunar Module in the National Air and Space Museum |
The initial design iteration had the LEM with three landing legs. It was felt that three legs, though the lightest configuration, was the least stable if one of the legs were damaged during landing. The next landing gear design iteration had five legs and was the most stable configuration for landing on an unknown terrain. That configuration was too heavy and the compromise was four landing legs.
The first LM flight was on January 22, 1968 when the unmanned LM-1 was launched on a Saturn IB for testing of propulsion systems in orbit. The next LM flight was aboard Apollo 9 using LM-3 on March 3, 1969 as a manned flight (McDivitt, Scott and Schweickart) to test a number of systems in Earth orbit including LM and CSM crew transit, LM propulsion (推进力), separation and docking. Apollo 10, launched on May 18, 1969, was another series of tests, this time in lunar orbit with the LM separating and descending to within 10 km of the surface. From the successful tests the LM successfully descended and ascended from the lunar surface with Apollo 11.
In April 1970, the lunar module Aquarius played an unexpected role in saving the lives of the three astronauts of the Apollo 13 mission (Commander James A. Lovell Jr., CSM pilot John L. Swigert Jr., and LM pilot Fred W. Haise Jr.), after an electrical short circuit caused an oxygen tank in that mission's service module to explode. Aquarius served as a refuge for the astronauts during their return to Earth, while its batteries were used to recharge the vital re-entry batteries of the command module that brought the astronauts through the Earth's atmosphere and to a safe splashdown on April 17, 1970. The LM's descent engine, designed to slow the vehicle during its descent to the moon, was used to accelerate the Apollo 13 spacecraft around the moon and back to Earth. After the accident, the LM's systems, designed to support two astronauts for 45 hours, actually supported three astronauts for 90 hours.
考考你
用今日所学将下面的句子译成英语。
1. 我们决定坚持以前的计划。
2. 爸爸正在计算税款,孩子们却在烦扰他。
3. Trudy 错失了晋升的机会。
From the earth to the moon《从地球到月球》精讲之三
1. 离开之前你得把房间收拾好。
Square away the room before you leave.
2. 你在给谁打电话?
Who's on the line?
3. 我非常明白你话的意思。
I catch your words five by five.
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