August, 2005: NASA officially publicises a space exploration program based on this and gives a detailed scheme of man's return to the moon.
On 16th July, 1969, Apollo 11, with 3 astronauts aboard, took off and began man's first exploration of the Moon. After a fly of about 380,000km, Apollo 11 got into the orbit of the Moon on 21st July. Astronauts Neil Armstrong and Buzz Aldrin took the lunar module and landed on the Mare Tranquillitatis.
Neil Armstrong got out of the module first. After a look around, he climbed off the staircase step by step. He touched the Moon surface first with his left foot and, finding that it sank but a little, gathered up his courage and put his right foot on the lunar surface, too. Man accomplished the deed of planting his footprints on an outer-terrestrial planet.
After the success of Apollo 11, NASA launched a series of Apollo spacecrafts from November, 1969 to December, 1972. All of them fulfilled their tasks except for Apollo 13, which was forced to suspend the mission because of an explosion of an oxygen tank in the service module. The US made a decision to carry out no more Moon-landing expedition in the future several decades after the Apollo program.
Thirty years after the Apollo program, American President George W. Bush proposed in early 2004 the Vision for Space Exploration. That is to say, man is going to be on the Moon again to build a lunar base in 2008 and make preparations for landing on the Mars from 2020 on. In August, 2005, NASA has officially publicised a space exploration program based on this Vision and given a detailed scheme of man's return to the Moon.
Conveyance - new generation manned spacecraft CEV
The means of conveyance is the first question to be dealt with. Though the Apollo spacecrafts were products back to the 1960's, the ones men are going to use bear striking similarities to it. As the Saturn V rocket has been out of production for over 30 years, NASA has to find new large rockets to send man back to the Moon.
There were longtime disputes over which kind of propulsion system should be adopted among the NASA engineers. The first choice is a space shuttle propulsion system and the other the rocket propulsion system for satellite launching. The former was chosen, because it cost less and had strong driving force.
The whole electropult will be composed of five shuttle main engines and a large propulsive rocket. The rocket is as high as 40 storeys and has a carrying capacity up to 125 tons, almost comparable to that of Saturn V. The expense for every launch is US$54million, almost as much as that for a liftup of space shuttle.
At the same time, in order to find substitutes for the space shuttle to be out of service in 2010, the NASA engineers are working on a new generation manned aerocraft CEV(Crew Exploration Vehicle), whose task is to send the astronauts into the deep space outside of the near-earth orbits. The exterior protective coating can be used for ten times and is replaceable. The first edition of CEV can hold three persons and make several flights between Earth and the international space station. It can also carry freight in addition. The maturer edition of CEV will be able to carry six persons to the Mars.
In July, 2005 NASA has authorised two contracts each worthy US$28 million, the contractors including Lockheed Martin and Boeing. The two contracts are signed for sponsoring the assessment of the CEV program before July, 2006. In order to shorten the interval between the retirement of the space shuttles and the virgin flight of the CEV, NASA will move up to early 2006 to choose a company to be in charge of the development of the CEV system.
The CEV looks very much like the Apollo spacecrafts in apperance but has an interior space twice as much as that of the Apollos. It consists of a command module and a service module, the former of which isthe control centre as well as where the astronaunts live and work. During the flight betweem the Moon and Earth, the 12-ton command module will be provided with the propulsive force by the service module which is combined to it.
The first manned flight of the CEV is due in 2011 when it will be carried by a pencil-shaped rocket to the international space station. The mission will cost US$280 million.
Beside a CEV, the astronauts will need a lander to get onto the Moon. The main function of a lander is to help the CEV in the journeys between the Moon orbit and its surface. Also constructed similar to the Apollo, it's composed of an ascent stage and a descent stage. The descent stage is a 4-foot stand equiped with a rocket engine. When leaving the Moon, the ascent stage will separate with the descent stage and carry the astronaut back to the Moon orbit. The lander of the CEV can carry four astronauts, while that of the Apollo could only carry two. The Moon landing program is scheduled to be in full swing in 2010 and all the spacecrafts needed for the landing is estimated to be completed in 2018.
Manner of Landing--Lunar Orbital Assemblage
The specifics of the landing remain to be agreed on after the problem of conveyance is solved. The biggest technical problem the aeronautical engineers encountered in the 1960's when making plans of the first Moon flight was how to land on the Moon surface. There were many alternatives suggested by the engineers for the most optimal plan.
The first one was a direct landing: to launch a Saturn VIII rocket, which was to travel and land on the surface of the Moon and fly back to Earth. However, the size of the rockets of that time deemed it impossible to carry fuel enough for the entire flight. Another scheme is called "orbital assemblage in Earth orbit", namely, to launch several small rockets and send the needed equipments into space in batches. These small rockets were to meet in the Earth orbit and assemble into a large spacecraft. This conception was given up in 1962 for there were too many unknowable factors in assembling a spacecraft in space.
The engineers who designed the Apollos finally adopted the third proposal --"orbital assemblage in Lunar orbit". The astronauts and all necessary equipments would be sent into space by a Saturn V. After leaving the Earth orbit, the third stage of the rocket would fly towards the Moon. Once in the lunar orbit, the command module and the sevice module of Apollo would separate with the lander. Two astronauts were going to get on the lunar surface in the lander, while the third stayed in the command module. When the lander returned to the Moon orbit, it would combine itself with the command module and carry the astronauts back to Earth.
Forty years later, the engineers of NASA are faced with the same choice. The new landing steps are more or less the same with that of Apollo, but because there will be more astronauts and scientific equipments this time, some points of the "Orbital Assemblage in Earth Orbit" scheme are added to the new one.
In the new Moon flight, a rocket with powerful propulsion will send the lander and the cargo module into space and is followed by another smaller rocket sending the CEV into space. After the three are all in the Earth orbit, they will combine into one.
The subsequent process is the same with the Apollo landing on the whole. Four astronauts will land on the Moon surface in a lander. After one week, the lander will leave the surface to meet the CEV which has been waiting in the lunar orbit and return to Earth. Before entering the aerosphere, the previously linked command module will discard the service module and after flying through the atmosphere, it will come down on the land with a parachute. Before the landing, however, the command module will fly over the Pacific Ocean and can land on the water in case of emergency.
Objective of Landing--a Lunar Base on the Rim of the Crater
Scientists believe that the value of a lunar return lies more in the exploration of farther planets with the Moon as a sringboard than gaining the knowladge of the origin of the Moon and its relation with Earth. A lunar base, therefore, will be the ultimate goal of the Moon landing.
NASA proposes that the US carry out at least two Moon landing missions every year since 2018. The first astronauts will make use of every resources available on the Moon and in the end establish a lunar base. The base will be like the scientific research stations at the south pole and comprise a living area, a power station, and a communication system. With a permanent base, the astronauts will be able to carry out longtime experiments covering fields of astrobiology, geography, astronomy, and physics. Other researches will be conducted to test the physical reaction of humans in the outer space environment of low gravity and strong solar radiation.
The scientists have located the ideal spot for the lunar base--the Shackleton crater at the lunar south pole, the rim of which is illuminated for about 80% of the lunar day. There are yet another two regions 10 kilometers away from the crater, where the sun shines for 98% of the time of a whole day. The scientists are planning to place the solar energy equipments in sunny areas and connect the base with them through microwave or cables, thus providing the area at the rim of the crater with solar energy virtually all the time. The North Pole on the Moon is smoother than the South Pole, but there might be a perpetual shaded area of up to 13,000 square kilometers.
The scientists also suppose there is a rich strorage of high hydrogen, which is one of the main fuels used in space exploration, in the areas aound the Shackleton crater. There may also be permafrost in some perpetual shaded areas inside the crater, which will not only satisfy the need of drinking water of the Moon dwellers but also be used to produce fuels for the spacecrafts. With these resources on Moon, the astronauts can set up systems of electricity, communication, and navigation as well as the dwellings for the forerunners of the human exploration of the Moon. Other places that may be selected for the base include the lunar North Pole, three sites on the farside of the Moon, and the Mare Tranquillitatis where the Apollo landed in 1969.
There must be an experiment module in the base for the test of lunar substances, the health of base dwellers, and food, a living module, an unpressurised storage module, a small chemical plant for processing lunar substances, a connective module with an observation room and an airlock chamber which allows the astronauts to go to and from the Moon surface, and two lunar roving vehicles, which the astronauts drive looking for fuels and water on the barren Moon surface. Long standing memebers on the Moon should include the commander, a mechanic, a mechanician, a doctor, a geologist, a chemist, and a biologist. The base members take shifts every two months, each time three or four members.
With products of the chemical plant and architectural materials, the astronauts are able to extend the base to one from which the mankind flies to the Mars and increase the productivity of the laboratory to 100,000 tons a year. But of course these are probably to be seen in the next century.
Perspective Plan--Landing on the Mars with Robots
On 12nd August, 2005, NASA successfully sent off a new model of Mars orbital reconnaissance aerocraft. It entered the orbit in March, 2006 and will readjust about 190 miles above the Mars surface circling around it. If the mission is accomplished, the rover will become another great help for human's exploration of this red planet. With the instruments such as precision cameras, the orbiter will take pictures of the minutest landscape details of the Martian surface, which will help the scientist locate the ideal spot for human landing.
There are not few rovers in the Martian orbit and on its surface. In the orbit are the Mars Global Surveyor and the Mars Odyssey of the United States and the European Mars Express. More remarkable are the rovers Spirit and Opportunity which are "rangering" on the Martian surface. Though the implementation of man's landing on the Mars will be after 2020, the rough conception has taken form.
The Martian landing is obviously much more difficult, compared to the Lunar landing. The Moon is but several days journey away from Earth, while a single manned flight to the Mars will take half a year. In terms of the scale, a Moon exploration needs only two rocket, while a manned Martian exploration needs four or five big rockets to send the manned aerocraft and other scientific instruments into space. Meanwhile, the same type of powerful propulsive engine the Saturn V rocket used may be put into use again. A Martian base must be completed before the exploration spacecraft with six astronauts aboard lifts up. The engineers on Earth will help build a control centre, the systems of electricity and communications on the Mars through long distance control system and at the same prepare a manned homeward spacecraft.
After the landing, the astronauts will spend 500 days surveying the Martian surface and doing research. The one object paid with the most attention is to look for the possible microbial life on the planet. The astronauts will try to find out oxygen and water, the two essential elements for life in the surface circumstance and try to obtain lox and liquid methane, the latter of which provides the main power supply in the launching stage of the rover. The scientists have suggested that the astronauts be able to collect fuels for the return flight, for there's a little methane in the Martian atmosphere.
In order to fully prepare the humans for landing on the Mars, NASA will launch the Phoenix Mars lander in 2007. NASA has also planned the liftoff of the third generation Martian rover named the Mars Science Laboratory in December, 2009, which is to reach its destination in October the next year. With a weight up to 600kg and the size of a jeep, the Mars Science Laboratory can be called "large" compared with the Martian exploration rovers Spirit and Opportunity. It will carry two laboratories, each including an instrument module as heavy as 30kg. The moving capacity of the new rover will also be greatly improved to be able to drive on a slope of 60 degrees; its power supply will also upgraded from solar energy batteries to nuclear energy and thus greatly increase the journey length and the service life and mobility. The designed service life is at least two years.
Scientist partisipating in the Martian exploration explain that NASA hopes to know as much as possible about the red planet before humans set foot on the Mars. In accordance with more specific tasks, Maritian robots will each have their particular features. NASA is developing a telecontrolled flying wing which is to be the "Martian glider" carrying out low flights near the Martian surface. The the model in test has a 2.4-metre wingspan and is powered by solar energy. The wingspan of the Martian flying wings will be extended to 20 metres and the wings will be retractable. The scientists expect the flying wings will adapt to the Martian environment and be able to fly and land in the tough Martian weather, thus helping the engineers develop the safe landing system of manned spacecrafts.
When on the Mars surface, the Mars flying wing may, for its ability to generate solar energy, be also used as a power station for other explorative devices that land on the surface. Another kind of Martian robots resemble snakes a lot , in apperance and in manner, moving zigzag on the Martian deserts. Another model named "Tumbleweed" specifically adapted to the Martian deserts is also developed by the Jet Propulsion Laboratory of NASA. The size of a volleyball, it can move around adroitly in the deserts.
The more powerful Martian robots will be programmed to build Martian bases suitable for human living apart from detect the Martian upper environment and collect statistics. On the future Martian surface, there will be a kind of robot shaped like a bucket shovel truck on a construction site but more agile and able to work completely intellectulised. Able to dig on soil or sand, this type of robot can replace humans to explore those tough places or help repair or build Martian bases.
When the first human astronauts get on the Mars, they are very likely to have the company of robots, which will make the landing on the Mars safer. At present, the scientists and engineers at the Ames Laboratory of NASA are planning on the simulation of the geology and landscape on the Moon and the Mars in an indoor laboratory and doing research in how robots can help man in such environments build bases, test equipments, and use digging tools. They are experimenting on the robonautB, a kind of robots with some human traits. They expect the space robots will be able to receive commands from human astronauts, display reactions alike humans, give advices or ask for them when necessary, and have the ability to act on their own.
Challenges--Health Hazard From the Outer Space Environment and Budget Impediment
Of course, an exploration program, however grand it is, is faced with technological and practical challenges. The first question is how to make sure of the health of the astronauts in the unknown outer space environment.
The scientists have always been worried about the damage done by the harmful solar radiation to the astronauts. Research reveals that an astronaut who stays long in the low Earth orbit suffers a risk of fatal cancer 3% higher than a common person, and scientists know yet little about the harm that might be caused by the outer space radiation. A large-scale solar storm in August, 1972 is the strongest solar radiation event ever recorded. The engineers are hoping to develop a CEV protective coating which can defend against a radiation four times stronger than that. NASA predicts a cancer risk 2.9% lower with a CEV coated with aluminium.
Within the known technological and hazardous range, NASA predicts a relatively low risk of the lunar exploration on the whole. Statistics show the probability of failure of the adventure to be lower than 6.3%, the probability of the astronauts in life danger to be 1.3%, while the evaluation of the 1962's Apollo lunar mission showed a probability of the astronauts in danger as 22%.
Beside technological risks, the Moon landing plan is faced with many realistic problems in accordance with political changes. The dispute over the astronomical cost of the scientific programs have long been under way. The expenses are estimated to have amounted to about US$217 billion by 2025, only US$7 billion less than the fiscal budget for the Space Exploration Department of NASA for the next 20 years. In other words, NASA will spend almost all its financial resources on the Moon landing program.
Michael Griffin, NASA chief administrator, made great efforts to reconcentrate the attention of NASA on the Lunar return in an attempt to confine the cost to the budget. Griffin spoke at the Congress 28th. June, "I hope you'll see a logical, simple, and direct scheme." A person in the NASA management said, "It's no possible possible for us to deal with the Lunar return programm as with some trivialities. and Griffin is very clear about this. To achieve our goal, we must be more innovative fiscally and technologically.
The most costly stage will be the final five years of the space shuttle's service life, because NASA has to undertake both the expenses of the shuttle in service and the development of new aerocrafts. But the high officials at NASA believe the financial source is guaranteed as long as the budget is not exceeded.
The fiscal budget of NASA in 2006 will be US$17 billion. If the yearly average budget of NASA in the future 20 years is US$20 billion, the Moon exploration program will take up 54% of the US$400 billion budget. The Moon exploration program has won support from the White House and the Congree, but before the blueprint finally comes true, there are still practical ordeals to overcome--the program must gain approval of three presidents and five congresses. Nevertheless, the apologists of the program are positively confident about this, as stated by a senator, "I believe people will be again ambitious of space exploration under the leadership of a foresighted president. The Congress will also give its full support, because the Congress stands for the wishes of the America."
The Exploarations of the United Stated of the Moon and the Mars
From 1961 to 1967
The United States launched nine Rangers, seven Explorers, and five Lunar Obiters for the reconnaissance of the Moon.
In the Year 1965
The space probe Mariner 4 of the United States flies by the Mars and returns the first pictures of the Martian surface.
20th July, 1969
The American astronaut Neil Armstrong landed on the Moon successfully in the spacecraft of Apollo 11 and left the first human footprint there. The excited Armstrong said, "That's one small step for man, but one giant leap for mankind."
17th April, 1970
The spacecraft Apollo 13 which was assigned the task of the third Moon landing was hindered by an explosion of an oxygen tank, but luckily, the three astronauts have returned successfully, which earned for this mission the name of "a successful failure".
In the Year 1975
The United States launched Viking 1 and Viking 2 orbiters, which reached the Mars in 1976.
6th January, 1998
NASA sent off the Lunar Prospector, which discovered ice at the North and South Poles on the Moon. The ice is estimated to be 10 billion tons at most.
In the Year 2001
In 2001, the United States launched the Odyssey, which arrived in the Mars, its major task being looking for water or ice on the planet and exploring the environment.
June, 2003
The United States launched two Mars exploration rovers, Spirit and Opportunity, which landed successfully in January, 2004 and which are still doing their reconnaissance work on the Martian surface after 15 months of service which is far extended from their scheduled mission life.
12th August, 2005
The United States successfully sent off the Mars reconnaissance orbiter, which is due to enter the Martian orbit in March, 2006 and readjust to 190 miles above the Martian surface to circle around the Mars. Its major task is to look for the possible water on Mars and make preparations for man's landing on the Mars.