It's the same for all the missions. They had to balance the risks against the science return. The EVA is one of the riskiest parts of the mission. So if your main objective is to get as many as possible humans to the Moon and back, minimize the EVA.
If your main objective is the science, then you might then spend a lot more time on the Moon for each mission, and send fewer people there, to minimize the number who risk their lives and get as much science return as you can. Lower cost, much more science, slightly more risk for each mission, but the total number of people who risk their lives is less because you have fewer missions in total.
They could have spent weeks on the Moon. Early plans even had a single astronaut land on the Moon and spend months or a year there continuously resupplied from Earth.
For the mission controllers whose main objective was to return the humans safely, then ideally you'd have no EVA at all. Or they just get out of the lander, symbolically touch foot on the Moon and immediately return.
Makes sense that Apollo 11 as the first mission should have a very short EVA as the first mission, there was so much else of danger in what they did, don't want to add to them, given that they did have a mission architecture that permitted them to come back quickly.
But after that it was a bit of a balancing act between the scientific objectives ideally to spend as much time on the Moon as possible - scientifically the most interesting part of the trip - and the objective to get the crew back safely with the minimum of risk.
It's the same also on the ISS. Though there have been no fatal accidents or even injuries, the EVA is the most dangerous part of missions there too. The reason there have been no accidents is because they are professionals who take a lot of care to prevent them, and even so there has been one rather close call. Spacesuit Leak That Nearly Drowned Astronaut Could Have Been Avoided
After all you are surrounded by vacuum, you are in a kind of mini spaceship, but compressed into a tiny package, with many components that can go wrong, you have to prevent overheating, provide oxygen. The astronauts on the Moon also had issues with co-ordination, falling over quite often while doing simple tasks in the unfamiliar gravity such as trying to take a core sample. And a damaged spacesuit could mean no oxygen, and not able to get back in time. You also have hazards of micrometeorites as well with only a thin spacesuit to protect you and the equipment that keeps you alive.
And on the Moon you also have the additional hazard of solar storms which could be especially dangerous if one of them struck while you are at your furthest point from the lunar module during an EVA (the LM would have provided some shelter that would help a bit). They went to the Moon close to solar max, and did get one solar storm but it happened between two missions with nobody on the Moon at the time.
I think you can still argue this endlessly whether they should have spent longer on the Moon for each mission. And also whether they should have continued and done many more missions.
As it turned out, the objective became to send one mission after another to the Moon, with the main objective almost, to send as many people there as possible, then get them back again safely, with the science objectives very much secondary to that aim to send lots of missions to the Moon and have many astronauts land there.
And then they stopped after the first really interesting scientific mission.
Certainly many scientists were disappointed when the program stopped, especially Carl Sagan - he wasn't particularly in favour of sending humans there - but having gone to all the expense of building the Apollo architecture, each individual mission didn't cost much at all in comparison. He compared it to buying a very expensive car, locking it in your garage, taking it out for a few drives, and then that's the end of it. And then when a friend asks you why you don't drive your wonderful new car any more you answer that it's because you spent so much on your car, so you can no longer afford the petrol to drive it.
He thought we should have kept going doing more missions.
In "The Cosmic Connection" he wrote:
Apollo 17 was the first mission to send a scientist to the Moon, a geologist. None of the previous missions had scientists, only astronauts with some geological field training. So, out of all those missions, in total we have only a single three day mission with one geologist to the Moon ever, so only one real scientific expedition there - rest of them assisted from Earth but through rather low resolution live video.
But it did mean that they didn't need to risk any more lives in these lunar missions when the thing closed down. And they did send many astronauts to the Moon and not one of them died during the missions.
If your main objective is the science, then you might then spend a lot more time on the Moon for each mission, and send fewer people there, to minimize the number who risk their lives and get as much science return as you can. Lower cost, much more science, slightly more risk for each mission, but the total number of people who risk their lives is less because you have fewer missions in total.
They could have spent weeks on the Moon. Early plans even had a single astronaut land on the Moon and spend months or a year there continuously resupplied from Earth.
For the mission controllers whose main objective was to return the humans safely, then ideally you'd have no EVA at all. Or they just get out of the lander, symbolically touch foot on the Moon and immediately return.
Makes sense that Apollo 11 as the first mission should have a very short EVA as the first mission, there was so much else of danger in what they did, don't want to add to them, given that they did have a mission architecture that permitted them to come back quickly.
But after that it was a bit of a balancing act between the scientific objectives ideally to spend as much time on the Moon as possible - scientifically the most interesting part of the trip - and the objective to get the crew back safely with the minimum of risk.
It's the same also on the ISS. Though there have been no fatal accidents or even injuries, the EVA is the most dangerous part of missions there too. The reason there have been no accidents is because they are professionals who take a lot of care to prevent them, and even so there has been one rather close call. Spacesuit Leak That Nearly Drowned Astronaut Could Have Been Avoided
After all you are surrounded by vacuum, you are in a kind of mini spaceship, but compressed into a tiny package, with many components that can go wrong, you have to prevent overheating, provide oxygen. The astronauts on the Moon also had issues with co-ordination, falling over quite often while doing simple tasks in the unfamiliar gravity such as trying to take a core sample. And a damaged spacesuit could mean no oxygen, and not able to get back in time. You also have hazards of micrometeorites as well with only a thin spacesuit to protect you and the equipment that keeps you alive.
And on the Moon you also have the additional hazard of solar storms which could be especially dangerous if one of them struck while you are at your furthest point from the lunar module during an EVA (the LM would have provided some shelter that would help a bit). They went to the Moon close to solar max, and did get one solar storm but it happened between two missions with nobody on the Moon at the time.
I think you can still argue this endlessly whether they should have spent longer on the Moon for each mission. And also whether they should have continued and done many more missions.
As it turned out, the objective became to send one mission after another to the Moon, with the main objective almost, to send as many people there as possible, then get them back again safely, with the science objectives very much secondary to that aim to send lots of missions to the Moon and have many astronauts land there.
And then they stopped after the first really interesting scientific mission.
Certainly many scientists were disappointed when the program stopped, especially Carl Sagan - he wasn't particularly in favour of sending humans there - but having gone to all the expense of building the Apollo architecture, each individual mission didn't cost much at all in comparison. He compared it to buying a very expensive car, locking it in your garage, taking it out for a few drives, and then that's the end of it. And then when a friend asks you why you don't drive your wonderful new car any more you answer that it's because you spent so much on your car, so you can no longer afford the petrol to drive it.
He thought we should have kept going doing more missions.
In "The Cosmic Connection" he wrote:
"Apollo 17 marked the end of the Apollo lunar missions. It seems clear that in the United States, that there will be a hiatus of a decade or more before further lunar exploration and lunar bases are organized. Apollo's primary orientation was never scientific. It was conceived at a time of political embarrassment for the United States. Several historians have suggested that a principal motivation of President Kennedy in organizing the Apollo program was to deflect public attention from the stinging defeat suffered at the Bay of Pigs invasion. Several tens of billions of dollars have been expended on the Apollo program. If the objective had been scientific exploration of the Moon, it could have been carried out much more effectively, for much less money, by unmanned vehicles. The early Apollo missions went to lunar sites of little scientific interest, because the safety of the astronauts was the prime, almost the only, concern. Only toward the very end of the Apollo series did scientific considerations play a significant role.
"The Apollo program ended just as the first scientist landed on the Moon. Harrison "Jack" Schmitt, a geologist, trained at Harvard, was one of the two-man crew of the Apollo 17 landing module. He was the first scientist to study the Moon from the surface of the Moon. It is ironic that just as the Apollo program became able to achieve this major advance in the scientific exploration of the Moon, it was canceled. Fittingly enough, the first scientist to land on the Moon was the last man to land on the Moon – at least in the foreseeable future. There are no plans for follow-on manned missions to the Moon either by the United States or, so far as we know, by the Soviet Union.
"The argument for cancellation of Apollo was economic. Yet the incremental cost of a given mission was in the many tens of millions of dollars, something like one thousandth the total cost of the Apollo program. It is very much as if, against the advice of my wife, I purchase a Rolls-Royce automobile. She argues that a Volkswagen could get me round just as well, but I feel that a Rolls-Royce would take my mind off the troubles of my job. I then spend so much money on the Rolls-Royce that, after driving it a little bit, I find I can drive it no more because I cannot afford the price of a tank of gas – which is about one thousandth the cost of a Rolls-Royce.
"I was one of the scientists opposed to an early Apollo mission. But once the Apollo technology was in hand, I was very much for its continuing usage. I believe the wrong decision was made twice – once in opting for early manned missions to the Moon, and later in abandoning such missions. After Apollo 17, the United States is left with no program, manned or unmanned, for exploration of the Moon. The Soviet Union has developed, in its Luna series of unmanned spacecraft, a proven and versatile capability for roving exploration of the lunar surface and automatic sample return to Earth.
"..."
Apollo 17 was the first mission to send a scientist to the Moon, a geologist. None of the previous missions had scientists, only astronauts with some geological field training. So, out of all those missions, in total we have only a single three day mission with one geologist to the Moon ever, so only one real scientific expedition there - rest of them assisted from Earth but through rather low resolution live video.
But it did mean that they didn't need to risk any more lives in these lunar missions when the thing closed down. And they did send many astronauts to the Moon and not one of them died during the missions.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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