The last humans to visit the moon left the lunar surface in apollo 17 at 5:55pm
eastern standard time on December 14th 1972, since then no humans
have been any further than on low Earth orbit missions and to the variety of space
stations that have existed since then. The question is now, where shall we go
next
do we make Mars the next great step forward or do we go back to the moon.
This time it's not down to the space race or national pride but it's in
expanding man's horizons to living elsewhere in the solar system other than
on the earth and maybe even making a profit while doing so. Even before the
Apollo missions had finished Werner von Braun the designer of the Saturn V
moon rocket wanted NASA to mount manned missions to Mars and the Soviets were
also drawing up their own plans to send men to Mars too. But by the early 1970's
the huge cost of the space race, the warming in relations between the
U.S. and the Soviet Union and the change of direction by NASA from the moon to
manned space stations and the Space Shuttle, effectively ended manned space
exploration beyond low Earth orbit and Mars which was always a much more
difficult challenge was off the agenda.
However the exploration of the solar system didn't stop, from the 1970s
onwards robotic probes and satellites have been sent all the planets in fact
they have been 40 Mars missions to date these included orbiters Landers and
Rovers but only 18 of them have actually been successful. Man has had a long-held
fascination with Mars going back to the Romans and although Mars is not the
closest planet to the earth that is actually Venus, it is the most earth-like.
In 1877 Giovanni schiaparelli reported that he saw long thin lines on the
Martian surface,
he called these canali
which means channels in Italian. Not long after the noted astronomer Percival
Lowell picked up on these and through his own observations came to believe
that Mars must have been not unlike the earth in the past and these "canals" were
the work of intelligent beings trying to irrigate the surface. By the turn of the
20th century the canals of Mars had become one of the most intense
obsessions in a history of science and although it was later proven to be
completely incorrect, it captured the public's imagination through numerous
newspaper and magazine articles of the time
this led to classic sci-fi books like "A princess of mars" by Edgar Rice Burroughs
and the "War of worlds" by HG wells. This fascination with the possibility that
Mars could have once been like the earth and that life may still exist is one of
the main driving factors behind sending manned missions there.
NASA has said that its aim is to land humans on Mars during the 2030's but many
question their ability to do this
considering the agency's budget and proposed use of expensive Apollo style
expendable rockets.
Meanwhile, Elon Musk says that his SpaceX will start sending unmanned cargo
flights to Mars starting in 2018 and then every 26 months thereafter. These
will be for future colonists to use which he says could be following as soon
as 2024 to arrive in 2025 Compared to the earth living on
Mars would not be an easy task,
there are a lot of technical issues to overcome let alone the human condition
and how that would affect the Mars colonists psychologically. So let's have
a look at some of the hurdles that any manned mission to Mars would have to
overcome.
Firstly there is the problem of just getting to Mars. Earth and Mars are on
different elliptical orbits at different speeds at their closest points
this can vary between 36 and
60 million miles and occurs roughly every two years between those times the
distance can increase up to 250 million miles.
This allows for only a narrow launch window and if launched at their closest
approaches and with current rocket technology the journey to Mars is around
a 150 days one way and this brings us onto one of the major
issues of a very long space journey, radiation. it's maybe just as well that
we didn't say any men to Mars in the 1970's and 80's after
the Apollo missions because they would have almost certainly died on route due
to the interplanetary radiation. Probes and robots which have been sent to Mars
over the years have revealed just how deadly interplanetary space and the
surface of Mars really is. Armed with this new information and the advancement
of Technology in the years since Apollo, we have been able to create new
radiation absorption technologies for the spacecraft and crew to protect them
from solar radiation. There are also ways to deflect charged particles from the
Sun like high energy protons and solar alpha particles by creating
electromagnetic fields around the spacecraft in the same way as the
Earth's magnetic field protects us. But once you're out into deep space and
beyond the protection of the Earth's magnetosphere there is another equally
dangerous form of radiation called galactic cosmic rays, these are
high-energy charged particles which are believed to originate from places like
the supermassive black hole at the center of our galaxy, supernova, quasars
and gamma-ray bursts which could be up to millions of light-years away. These
particles were first observed by the Apollo Crews as flashes of light which
they saw even with their eyes closed as the particles went through the walls of
the spacecraft and hit their retinas or optic
nerves. Galactic cosmic rays arrive in our solar system from every angle and
can easily pass through spacecraft and human tissues. These pose two problems,
firstly when they strike some of the spacecraft materials they can give off
powerful x-rays and creates lower secondary ionizing radiation like
neutrons and secondly like neutrons they can rip apart the molecules that make up
human tissue and DNA this can lead to cancer later but more worrying for the
crew is a new research has shown that they can damage brain cells at the
molecular level causing symptoms similar to Alzheimer's. This may take months to
manifest itself but the long journey to Mars would easily be enough time to
create permanent brain damage if the crew were not protected sufficiently.
When you arrive on Mars the problems don't stop there Mars itself has no
global magnetic field like the earth to deflect these energetic particles and
the thin atmosphere provides little in the way of protection to so any habitats
will still need to shield the occupants from radiation on the surface and will
probably need to be underground.
Although Mars has a 24.6 our day that matches the 12-hour day night cycle of
Earth it has only 37% percent of the Earth's gravity and is still not
known what long-term exposure to this low-gravity environment will do to the
human body. The atmosphere of Mars is 96% carbon dioxide with
only 0.13 percent of oxygen compared to be Earth's 20% percent
oxygen levels. Its atmospheric pressure is also just 0.6% of
that on the earth which technically be called a vacuum. You would have to wear a
pressure suit with an air supply to walk around on the Martian surface. A failure
of the suit system would mean death within minutes if you could not get back
to a safe habitat.
Add to this the average temperature is around
minus 55 degrees Celsius, although in the Martian summer the temperature the
equator can reach 20 degrees Celsius in the winter at the poles is as low as
minus 125 degrees Celsius. There are also huge dust storms can spring up at any
time and last for months
these can cover vast areas of the planet surface blocking out most of the
sunlight which would render solar panels, the staple power generation for most
spacecraft useless. You would have to bring your own nuclear powered
generators if you wanted a reliable source of electrical power for your stay
and before you could split water ice into hydrogen and oxygen for rocket fuel.
Then we have the problems that humans have been living under extreme
conditions. The nearest we have to Mars on earth is Antarctica which has a
slightly warmer average temperature of minus 49 degrees Celsius, a breathable
atmosphere, plenty of fresh water and no radiation. But many of the scientists
that work all year round in Antarctica suffer from a mental health disorder
called "winter over syndrome" which is characterized by symptoms such as
depression, irritability, aggressive behavior, insomnia and memory problems.
With the long journey to and from Mars and a prolonged or permanent stay
these conditions could be a lot worse. Performing mission-critical tasks or
just the manual job of building a colony under these conditions would be
extremely testing even for the best.
So whilst there is the urge to follow in Apollo's footsteps with an audacious
Mars mission, many countries are looking to the moon again but this time to build
manned basis develop technologies and use the moon as our launch pad to a rest
of the solar system.
Another reason to revisit the moon is the cost is significantly lower
especially if there is the potential of a huge profit to be made by mining it
rare and valuable resources. Mars on the other hand will be a massive financial
black hole. In comparison to Mars the moon is a much easier place to get men
to we've already done it with Apollo but the longest we stayed on the lunar
surface was for just over three days with Apollo 17. This new age of lunar
exploration will be a much more permanent affair now you would think
that as the previous leaders in lunar exploration NASA and the USA would be at
the front of the queue heading back to the moon but that may not be how it's
going to happen this time around.
NASA had plans to go back to the moon with the constellation program but those
were scrapped in 2010 by the Obama administration in favor of a flexible
path approach to space starting with landing a manned mission on a near-earth
asteroid first and then a manned Mars mission. The next lunar expeditions will
be a much more international affair with both Russia and China having said that
they will build permanently manned lunar bases and the European Space Agency has
said that he's interested in developing its "moon village" concept with other
international partners at around 237,000 miles
and with a journey time of around about three days establishing a lunar colony
would be a lot easier undertaking as supply Rockets can be sent on a regular
basis as well
shuttling people to and from Earth. There is still the radiation issue from
high-energy protons as you fly through Van Allen belts
but these are not difficult to shield against and this has already been
done with the Apollo missions. Once on the moon
there is no atmosphere or protective magnetic field so radiation is still
going to be a problem.
Most of the plans put forward for lunar bases are underground structures which
would give the inhabitants more protection from the solar and cosmic
radiation. As there is no atmosphere there is also no weather or any other
obstructions like the Martian dust storms to block the sunlight required to
use solar panels.
However the moon takes 29.5 Earth days for it to complete one rotation relative
to the Sun, if you had lunar bases on the moon's equator where the Apollo missions
landed it will be light for almost 15 days and in dark for the next 15. Just as
the area where the Apollo missions landed at the equator was flat, the poles
of the Moon are quite mountainous with deep craters and unlike the earth the
moon tilts over at only 1.54 degrees, so that the lunar polar regions
stay in almost permanent sunlight on the high points of the North Pole and the
floor of the deep craters of the South Pole where the Sun never shines is the
coldest place in the solar system where the temperature is around minus 243
degrees celsius and where water ice is believed to exist in large amounts. But
it's not just the water that could be used to make rocket fuel that the lunar
prospectors are interested in there are other resources like helium 3 which is
the main fuel candidate for future nuclear fusion reactors this is
extremely rare on earth that is believed to exist in large quantities on the
surface of the Moon. This helium-3 would be worth hundreds of billions of dollars
as a new fuel source.
The Chinese have said that it will be one of their primary goals once they are
on the moon to mine for helium-3. So with all this new interest in the moon from
Russia, China, India and the Europeans it seems strange that the US would just let
everybody else take the initiative. But as they say a week is a long time in
politics, so the six years since Obama said that the moon was off the table is
almost an eternity. Recent Congress hearings have been very critical of
NASA's Mars initiative attacking it for its clarity and cost which is likely to
be in the hundreds of billions of dollars and with narrowing budget is
hard to see how it will come to fruition. In a draft of the new appropriations
bill for NASA, Congress would look to remove the funding for the asteroid
mission and put the focus back on the moon which can be done with current
technology and working with the private space sector. So with a new president
arriving soon and many wanting to see America great again, NASA may well be on
a new flexible path back to the moon much sooner than would have been thought
possible a few years back and Mars may end up being the first celestial body to
be visited by a private space company.
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