reading materials

1. The Limitations of Space Travel
Why Can’t We Find ET?
It is becoming more and more widely accepted among scientists that we shouldn’t be asking if there is
life on other planets but rather where is the life outside Earth.
Life as we know it requires a certain set of conditions to
develop but with at least 100 billion galaxies in the universe, the
odds are strongly against Earth being the only planet where
those can be found. And, of course,
there is no guarantee that life on other
planets would resemble life here and
require the same conditions we do
(Kluger, 2016.) So, if there is life in a galaxy far, far away, why haven’t we met
them yet?
1. They’re far, far away
“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I
mean, you may think it's a long way down the road to the chemist's, but that's just
peanuts to space.”
- The Hitchhiker’s Guide to the Galaxy (Adams, 1979)
The distance between Earth and any other point in our solar system depends on where each is in its orbit
around the Sun. Mars, to which NASA is hoping to send manned missions in the 2030s (Wilson, 2016),
is approximately 56 million km from Earth at its closest point, 401 million km at its furthest (NASA,
n.d.). With current technology, a one-way trip to the red planet takes around 8 months (Loff, 2012) and
this is to a planet that, galactically speaking, is right next-door. The New Horizons mission to Pluto left
Earth on 19 January 2006 and didn’t reach its destination until 14 July 2015 (Talbert, 2015). And this is
still just within our own solar system, in which no planet appears to have the necessary conditions to
sustain life.
The closest rocky planet outside our solar simple is known simply as HD 219134b and lies 21 light years
away (Barnett, 2015). A light year is “the distance traversed by light in one year, about 5.88 trillion mi.
(9.46 trillion km)” (Dictionary.com, 2016). HD 219134b, unfortunately, lies too close to its sun to be
habitable. A planet very similar to Earth was discovered by the Kepler spacecraft in 2015 but it lies

2. 1,400 light years away (Barnett, 2015). Presently, our manned space shuttles (with people on them)
travel at about 28,000 km/hr. (Bray, 2015); at this speed it would take approximately 385,682 years to
reach.
2. We don’t have the technology
Humans have walked on the moon but so far do not have the necessary equipment to even visit Mars,
the next closest celestial body. This is because space shuttles and people have a lot of requirements to
stay functional on a long-term space flight, as you need to take
everything with you. The International Space Station can be
resupplied fairly frequently because it is only orbiting the Earth.
Once you enter deep space, you’re on your own.
To begin with, space shuttles consume an enormous amount of
power. The shuttle is powered by fuel cells in which hydrogen and
oxygen combine to form electrons, water, and heat. The electrons are
the source of electricity. This combination is called a chemical
reaction and the hydrogen and oxygen are called reactants. Some of
the hydrogen can be recycled but all of the oxygen is used in the reaction. That means that to produce
more electricity, you need more oxygen (NASA, 2002) and the shuttle can only carry so much.
Oxygen is, of course, also very important because it is what humans breathe. We also need food and
water and with longer flights, more of these necessities will have to be brought along. This means more
storage space, more weight, and more electricity to keep the whole thing running.
3. Stress on the human body and mind
Space is very different from Earth and those differences are very hard on the human body. The effects of
lower levels of gravity are especially tough, leading to loss of bone and muscle tissue. Reduced bone
density makes returned astronauts more prone to bone breaks. Vertebral discs (the bones that make up
your spine) that have become misaligned because of low gravity can lead to serious injuries once gravity
is reintroduced. Muscle mass is also lost with studies showing that on flights under 14 days, up to 1/3 of
muscle mass is lost. On longer flights, it is predicted that 20-40% of muscle mass could be lost. With
lost muscle comes lost strength, which makes it more difficult for astronauts to complete important tasks
while in space.
The International Space Station

3. Another very serious concern is exposure to radiation because the protection
of the Earth’s atmosphere is gone. As on this planet, too much radiation can
cause radiation poisoning and cancer. Time spent away from loved ones and
the stress of a high-pressure job with no escape can also cause negative
psychological effects. These issues are made worse if an astronaut is not
getting enough sleep or if they are having problems with other mission
members (Roberts, 2013). And, again, with longer flights these problems
will increase. With current technology, the human body could not withstand
a trip to another inhabitable planet.
Looking to the future
Science fiction fans shouldn’t give up just yet though. New advances are being made all the time.
Scientists are experimenting with the idea of a solar sail, which would propel the rocket forward during
the entire journey. Since there is nothing to stop a ship in space (no air resistance), this will allow it to
accelerate the entire time, thus building up an incredible speed.
Force fields to block radiation, space adapted plants for growing
food, and water and oxygen recycling systems are also being
looked at. To deal with the lack of gravity, a rotating, circular
ship could create a sense of gravity for those onboard. For
extreme distances, science fiction is inspiring some possible
solutions. The warp drive that makes intergalactic travel possible
on Star Trek is a notion physicists have been toying with for
decades and theoretical physicist Miguel Alcubierre published a paper in 1994 that said it was
theoretically possible. Another science fiction staple is suspended animation, which allows people to
sleep through the hundreds or thousands of years required to reach their destination. In 2006, scientists
at Massachusetts General Hospital were able to induce a reversible suspended animation in mice with
hydrogen sulfide (Science Channel, n.d.).
Neil Armstrong
A rotating ship to simulate gravity

4. Reading Comprehension Questions
1. Is the distance from Earth to another planet or moon always the same? Why or why not?
2. How long did it take New Horizons to reach Pluto?
3. What is a light year?
4. Why is it possible to take supplies to the International Space Station but not to a shuttle on a long
flight?
5. What two elements are combined in the space shuttle’s fuel cells?
6. What are the products of the fuel cell reaction?
7. Name three negative impacts of space travel on the human body.
8. What did scientists use to put mice in suspended animation?
9. You have been asked by your local government to create a comprehensive report on whether we
should attempt to fly people to potentially inhabitable planets as a means of “seeding” human life
outside our own solar system. Your report needs to break down the positives and negatives of
such a trip as well as explaining whether or not there is an actual need to “seed” ourselves (don’t
just say we should or shouldn’t, state your reasons). Lastly, you must state your expert opinion
on whether this should be carried out.

5. Reading Comprehension Answers
1. Is the distance from Earth to another planet or moon always the same? Why or why not?
No, the distance from Earth to any other point in the solar system depends on where each is in its
orbit around the Sun.
2. How long did it take New Horizons to reach Pluto?
Nine years, five months, and twenty-five days (9 ½ years)
3. What is a light year?
The distance light travels in an average solar year
4. Why is it possible to take supplies to the International Space Station but not to a shuttle on a long
flight?
The ISS is orbiting the Earth and so is fairly easy to reach. To resupply a shuttle in deep space,
you would have to catch up to it and the shuttle with the supplies would itself require supplies.
5. What two elements are combined in the space shuttle’s fuel cells?
Hydrogen and oxygen
6. What are the products of the fuel cell reaction?
Electrons, water, and heat
7. Name three negative impacts of space travel on the human body.
Loss of bone density, loss of muscle mass, exposure to radiation (also: misaligned spine and
psychological impacts
8. What did scientists use to put mice in suspended animation?
Hydrogen sulfide
9. You have been asked by your local government to create a comprehensive report on whether we
should attempt to fly people to potentially inhabitable planets as a means of “seeding” human life
outside our own solar system. Your report needs to break down the positives and negatives of
such a trip as well as explaining whether or not there is an actual need to “seed” ourselves (don’t
just say we should or shouldn’t, state your reasons). Lastly, you must state your expert opinion
on whether this should be carried out.

6. References
1. Adams, D. (1979). The hitchhiker’s guide to the galaxy. New York: Harmony Books.
2. Barnett, A. (2015, July 30). Nearest rocky planet outside our solar system found. CNN.
Retrieved 23 March 2016 from: http://www.cnn.com/2015/07/30/ us/exoplanet-discovered/.
3. Bray, N. (ed.) (2015, July 30). Space shuttle and international space station. Retrieved 23
March 2016 from: http://www.nasa.gov/centers/kennedy/
about/information/shuttle_faq.html#14.
4. Dictionary.com. (2016). Light year. Retrieved 23 March 2016 from:
http://www.dictionary.com/browse/light--year?s=t.
5. Kluger, J. (2016, February 22/29). The perfectly sane case for life in space. Time.
6. Loff, S. (ed.) (2012, October 10). Mars planning frequently asked questions. Retrieved 22
March 2016 from: http://www.nasa.gov/offices/ marsplanning/ faqs/.
7. National Aeronautics and Space Administration. (2002, April 7). Fuel cell power plants.
Retrieved 23 March 2016 from: http://spaceflight.nasa.gov/shuttle/
reference/shutref/orbiter/eps/pwrplants.html.
8. National Aeronautics and Space Administration. (n.d.) Mars: FAQ. Retrieved 22 March 2016
from: http://solarsystem.nasa.gov/planets/mars/faq.
9. Roberts, J. (ed.) (2013, August 21). How astronauts are affected by space exploration. Retrieved
24 March 2016 from: http://www.nasa.gov/externalflash/HRP_Feature/.
10. Science Channel. (n.d.). 10 technological innovations needed for deep space exploration.
Retrieved 23 March 2016 from: http://www.sciencechannel.com/topics/aliens-space/10-
technology- innovations-needed-for-deep-space-exploration/.
11. Talbert, T. (ed.) (2015, August 24). New Horizons: The first mission to the Pluto System and
the Kuiper Belt. Retrieved 23 March 2016 from:
https://www.nasa.gov/mission_pages/newhorizons/overview/index.html.
12. Wilson, J. (ed.). (2016, February 9). Journey to Mars overview. Retrieved 22 March 2016
from: http://www.nasa.gov/content/journey-to-mars- overview.