Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Exemplar for Internal Assessment Resource
Earth and Space Science Level 3
Resource title: Could aliens really exist?
This exemplar supports assessment against:
Achievement Standard 91415
Investigate an aspect of astronomy
Student and grade boundary specific exemplar
The material has been gathered from student material specific to an A or B assessment
resource.
Date version published by
Ministry of Education
December 2012
To support internal assessment from 2013
Introductory comments:
An aspect of astronomy may include:
• an event
• a discovery
• phenomena
• principles
• knowledge gained from space probes or telescopes.
Images have removed because of copyright and paragraphs not directly related to the task have also
been removed.
© Crown 2012
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: Low Excellence
1.
For Excellence the student needs to investigate comprehensively an aspect of astronomy. This
involves explaining the key links between the astronomy aspect and the key science.
The student has produced a report showing integrated links between explanation of the
astronomical aspects and explanations of the key science. Good understanding is lacking in
places which is why it is only a Low Excellence.
A wide range of reliable information was selected and processed related to the astronomical
aspect and the relevant science and sighted by the teacher.
Examples:
“For many years it was believed that life…exist under the surface where no sunlight would
reach.”
This paragraph shows integration between explanations of astronomical aspects and key
science.
“When searching for life in our solar system the most likely places where we are going to find it
are on Jupiter’s moon Europa…would protect organisms from radiation, as Europa has a very
weak atmosphere.”
This shows an explanation of an astronomical aspect, but there are no key science ideas such
as the extremophiles that could be found on Europa. These key science concepts are missing
from the final report hence a low Excellence.
The above paragraphs show integration between explanations of astronomical aspects and
science (key science ideas required for a secure Excellence).
For a more secure Excellence, full evidence of the justification for life in the solar system linked
to the key science is required.
© Crown 2012
Student 1: Low Excellence
Could Aliens really exist?
For many years scientists have been trying to find life in outer space, especially in our solar
system. On Earth there is a large range of both physical and chemical conditions which has
allowed complex life to evolve. As well as harbouring life such as humans, plants and
animals Earth also has a range of extremophiles which exist in the most extreme conditions
on Earth. If there is life surviving in the extreme conditions on Earth then it may be possible
for simple life to also exist on a range of other planets and moons which meet the
requirements to harbour simple life. Jupiter’s moon Europa, Saturn’s moon Titan and the
planet Mars are the most likely places for life to exist in our solar system.
Although complex life might not exist anywhere other than Earth in our solar system, it
could be possible that simple life such as bacteria and Archaea (which are a very primitive
form of bacteria) are living on other planets and moons in our solar system. The
requirements for simple life are much more basic than those for complex life. The three
essential requirements are liquid water, a carbon source, and an energy source. Liquid
water is one of the most important factors for life as it acts as a medium for nutrients to
diffuse into cells, and for wastes to exit the cell. Water is also a solvent (a liquid, solid or
gas, which dissolves another liquid, solid or gas), which many chemical substances can
dissolve into. This is essential for life as it allows important metabolic reactions to take
place. These reactions are essential as they allow organisms to survive, maintain their
structures, grow and reproduce.
A Carbon source is another requirement which is important for the most basic forms of life.
Carbon is important to life as it can chemically bond with up to four other atoms to create a
range of organic molecules such as lipids, carbohydrates, proteins, and nucleic acids.
Because carbon is the building block for all forms of life on Earth, it is likely that any life in
our Solar System would also be carbon-based.
Another requirement for life is that there must be an energy source. Energy is an essential
for all life as it fuels chemical reactions which must be carried out in order for any life to be
able to exist. For many years it was believed that life was dependant on solar energy from
the Sun, which made the presence of life on other planets and moons seem less likely,
however on Earth microbes have been discovered who gain energy from minerals such as
sulphates and nitrates. Therefore organisms could exist on other planets or moons such as
Europa where life would have to exist under the surface where no sunlight would reach.
When we search for life on other planets the organisms which are living in extreme
environments on Earth gives us an idea on what environments we might find life in and
what form they may be in. Earth has a range of extreme environments ranging from being
extremely hot, extremely cold, very acidic, very alkaline, salty, and there are even places
with intense radiation. These environments are the ones likely to be common-place on other
planets and moons so by being able to find life in these conditions in the form of
extremophiles (microbes which can survive in extreme environments) it means that it is
definitely possible for this type of life to be able to exist elsewhere in our solar system.
Biologists have discovered a wide range of extremophiles on Earth, mostly bacteria and
Archaea, such as Thermophiles, Psychrophiles, Halophiles, Acidophiles, Alkaliphiles ,
Xerophiles, radiation resistant microbes and many others surviving under extreme
conditions.
When searching for life in our solar system the most likely places where we are going to find
it are on Jupiter’s moon Europa, Saturn’s moon Titan and on Mars.
Europa is slightly smaller than our moon, and it is thought to have a rocky mantle, iron core,
and a liquid ocean of salty water which covers the whole surface of Europa, and is
completely frozen over. The temperature on Europa is roughly -220 degrees Celsius at the
poles, and around -160 degrees Celsius on the rest of the moon. These temperatures are
due to the tidal forces, caused by Jupiter’s gravity, which makes the sea below the surface
rise and fall. The friction caused from the motion of the tides has resulted in Europa being
warmer than it would be without the tidal heating. This motion is also likely to have caused
the cracks which can be seen in images of Europa. Life being under the surface of Europa
would protect organisms from radiation, as Europa has a very weak atmosphere.
Titan which is a moon of Saturn’s is another place in our solar system where it may be
possible for simple life to exist. Titan resembles Earth in many ways as a space probe has
shown it to have mountains, dunes, lakes and possibly volcanoes. As well as this the
weather on Titan appears to have erased most of its meteorite craters, which is what the
weather on Earth has done as well. Another similarity between Titan and Earth is that they
both have an atmosphere consisting of mainly nitrogen, Earth is 78% whilst Titan’s is 90%.
Titan’s thick atmosphere would protect organisms living on the moon from the harmful
ultraviolent radiation rays of the Sun. On Titan there is very little oxygen in the atmosphere,
meaning that any life living there would not be breathing oxygen or using it as part of their
feeding process.
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: High Merit
2.
For Merit the student needs to investigate in depth an aspect of astronomy. This involves
explaining the key science relevant to the astronomical aspect.
The student has produced a report with the astronomical aspects and the key science
explained, but with only minimal integrated links as required for Excellence. A wide range of
reliable information has been selected and processed related to the astronomical aspect and
the relevant science and sighted by the teacher.
Examples:
“The most important of these is liquid water and all searches for life on other planets and moons
are focused on this…This makes it one of a kind. Water is the solvent that acts as a place for
the chemical reactions of life to take place.”
The key idea is well explained and at a Merit level.
“There are also microorganisms that live deep in the earth’s crust under conditions of extreme
heat, crushing pressure and very little food. They are found in the pores between the particles of
sediments…Extremophiles such as this could possibly survive in the nutrient deficient Mars and
Europa.”
Links to conditions are not at Excellence level and this stops the grade being higher.
“After Earth, Mars is the planet with the most favorable climate in our solar system for life…The
conditions underground will be extremely harsh but scientist still believe there could be life there
as life can be found in extremely harsh conditions on earth…Mars unless it was in an enclosed
environment, and not for a long period of time.”
Again the links to conditions are not at Excellence level because key links are not given.
To reach Excellence full evidence of the justification of the astronomical aspects linked to the
key science is required.
© Crown 2012
Student 2: High Merit
Could Aliens Really Exist?
There are three planets and moons that are possible candidates for life. These are Mars,
Titan (Saturn’s biggest moon) and Europa (a moon of Jupiter) and they have conditions in
which life could exist. There is also a range of extreme physical and chemical conditions in
which life exists on earth. These life forms are called extremophiles. This is the kind of life
that is being looked for on other planets and moons.
The first thing that needs to be considered when talking about life on other planets and
moons is the conditions that life requires. The four conditions needed for life are the
presence of liquid water, a carbon source, a source of energy and suitable environmental
conditions.
The most important of these is liquid water and all searches for life on other planets and
moons are focused on this. Water is an extremely versatile substance. It can be used for
dissolving nutrients for ingestion or waste for excretion. Water also has the widest range of
temperatures in which it can stay liquid in form out of any other chemical. This makes it one
of a kind. Water is the solvent that acts as a place for the chemical reactions of life to take
place.
There are a range of extreme conditions on Earth in which life surprisingly exists. Scientists
are now rethinking what conditions on other planets and moons life could exist.
Microorganisms have been found in conditions of high temperatures, low temperatures,
radiation, high pressure, without oxygen and without water. Such organisms are called
extremophiles and are generally bacteria or Archea. An example is the bacteria that can live
in hot pools at 1200C in hot pools around Rotorua.
There are also microorganisms that live deep in the earth’s crust under conditions of
extreme heat, crushing pressure and very little food. They are found in the pores between
the particles of sediments. These creatures feed on and get oxygen from chemicals such as
sulfates and nitrates. There are also two extremophiles that exist in the bottom of Ace lake
in Antarctica that live in extreme cold. The two organisms, called Methanogenium frigidum
and Methanococcoides burtonii, produce methane and are known as methanogens. This
made scientists think that extremophiles similar to this may exist in the possible water under
the frozen sea of Europa. Oligotrophs are another type of extremophile that survives on a
extremely low level of nutrients. “Oligotrophic environments include deep oceanic sediments,
caves, glacial and polar ice, deep subsurface soil, aquifers, ocean waters, and leached soils”.
Extremophiles such as this could possibly survive in the nutrient deficient Mars and Europa.
The three most likely candidates for life on other planets are Mars, Europa and Titan. Mars is
the planet most similar to Earth. Mars has volcanoes, valleys, deserts, and polar icecaps
similar to those on Earth. It also has seasons like Earth as its axis is on a tilt. The fact that
Mars has similarities with earth have led scientists to search it for life. But if there is life on
Mars it is most likely underground because there is ultraviolet radiation on the surface of
Mars. After Earth, Mars is the planet with the most favorable climate in our solar system for
life. By looking at the geological features on the Mars surface, it can be seen that water
once existed on Mars. It may still exist under the surface but the atmosphere is now too thin
and it is too cold for liquid water to exist on the surface now. The area on Mars where
scientists are hoping to find life is underground. “Deep subsurface water deposits near the
planet's liquid core might form a present-day habitat for life”. But the life that they may find
there will only be very simple like the micro organisms found on Earth. The conditions
underground will be extremely harsh but scientist still believe there could be life there as life
can be found in extremely harsh conditions on earth. There are parts of Mars with far less
harsh conditions than these found on earth. This make scientists think that life may exist on
Mars. Even though there may be life on Mars, human life could never exist on Mars unless it
was in an enclosed environment, and not for a long period of time.
The next candidate for life in space is Titan. Titan is on of Saturns moons. It isn’t a great
candidate as there is no liquid water on the surface but it has lake filled with “...liquid
hydrocarbons, or molecules made of hydrogen and carbon, such as methane and ethane”.
The fact that Titan has liquid on its surface makes it a candidate for life. But life as we know
it could not exist on Titan because of the extreme cold and the lack of carbon dioxide in the
atmosphere. If there was life on Titan it would most likely be silicon based as Titan has the
conditions for these life forms to survive. These conditions are lack of liquid water, lack of
oxygen and low temperatures. What makes silicon based life forms different from the life
forms we know is that they uses silicon to build their cells and not carbon like Earth life
forms do.
The last candidate for life is Europa. Europa is the next most likely candidate for life after
Mars. It is one of Jupiter’s moons. Europa is covered in a frozen ocean of ice. It is thought
that there could be life in water under the ice. There may be strong tidal heat in Europa’s
core keeping it warm enough to have liquid water under the layer of ice. There is no
evidence that there may be life on Europa but the possible presence of water under the
frozen sea means that scientists want to send probes there.
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: Low Merit
3.
For Merit the student needs to investigate in depth an aspect of astronomy. This involves
explaining the key science relevant to the astronomical aspect.
The student has produced a report with the astronomical aspects and key science explained but
without a lot of detail. A wide range of reliable information has been selected and processed
related to the astronomical aspect and the relevant science and sighted by the teacher.
Examples:
“For liquid water to be present on Mars…so the prospect of complex life on Mars today is
unlikely.”
The student has provided an explanation of conditions on Mars and the 2 moons possibly
suitable for life.
0
“Bacteria have been found living in hot geothermal pools at temperatures of 120 Celsius…This
means that even if the sun does not reach a distant planet, there is still the possibility of
primitive life forms living there.”
Key science ideas have been explained but are lacking in detail. This is why this response is a
Low Merit grade.
To achieve more securely at Merit the science needs to be more fully explained.
© Crown 2012
Student 3: Low Merit
Planets where life could be found:
Mars
There is a large amount of evidence to suggest that there was once water on Mars. Satellite
images or Mars show that there is a network of river-like channels scattered across the
surface of Mars which may have once contained running water, either on the surface or just
underground.
For liquid water to be present on Mars today the atmosphere would have to be thicker and
the temperature hotter. Today the average temperature on mars is -63°C, liquid water only
exists above 0°C. The most likely place for water to exist is underground or at the poles.
The only obvious source of energy on Mars is the sun. If there were life on Mars it would
likely take the form of plants or organisms that rely on solar radiation to provide energy. The
soil on Mars has been tested to see if it contains any of the elements required for metabolic
action. Unfortunately nothing has been found, so the prospect of complex life on Mars today
is unlikely.
Titan
Very close observations of Titan have found traces of water vapour. This water vapour has
possibly been transferred to Titan from the distant icy rings of Saturn. Titan is very similar
to an ancient Earth, giving us reason to believe that there is a great possibility of life on
Titan. However, the highest surface temperature recorded on Titan is -100°C, which means
there is no possibility of liquid water on the surface, one of the fundamental factors in
sustaining life. Titan’s surface is hidden under a layer of methane clouds, but there have
been sightings of both light and dark areas on Titan’s surface which could be due to frozen
continents or hydrocarbon lakes. It appears that Titan’s surface is mostly covered with ice,
silicate rocks and minor lakes.
The features of Titan are very close to that of a young Earth. Titan contains the elements
that organisms require to metabolise. There is oxygen in the form of carbon monoxide and
carbon dioxide. A thick layer of methane clouds covers the surface, with organic compounds
raining onto the surface. It is possible that life could exist there.
Europa
Europa is one of Jupiter’s moons and is completely ice covered. Several kilometres below the
ice may be oceans of liquid water. This water forms because the gravity of Jupiter pulls the
crust of Europa causing heat which melts the ice. Primitive life could exist in that ocean.
Also, hydrothermal vents may exist on the ocean floor and organisms could live around
them, feeding off the chemicals that are released there such as hydrogen sulphide.
Observations have also shown that Europa’s atmosphere is made up mainly of oxygen which
has been formed from cosmic rays hitting the ice and breaking it down to oxygen and
hydrogen.
Extremophiles
An extremophile is an organism that is able to survive and thrive in extreme conditions that
complex organisms could not. They are many bacteria or Archaea, a primitive form of
bacteria.
Bacteria have been found living in hot geothermal pools at temperatures of 1200 Celsius.
They also have been found deep underground, in highly alkaline or salty lakes, or in
conditions of high radiation. Many extremophiles don’t need sunlight. This is an interesting
discovery as it means that it is possible for life to survive without the use of the sun as an
energy source. This means that even if the sun does not reach a distant planet, there is still
the possibility of primitive life forms living there.
Archaea
Archaea are a group of single celled organisms that can live in pretty much any conditions,
such as volcanic hot springs, soils, oceans and marshlands. They have been found in
extreme conditions such as very salty lakes (halophiles), very hot water such as over 80 0C
(thermophiles) and high acidity such as below pH 2 (acidophiles).
Archaea may be the types of organisms that could be found on other planets or moons
because of their ability to live in extreme environments. Some extremophile habitats are
similar to those on Mars, and micro-organisms could travel there on meteorites.
The Possibility of Extra-Terrestrial Life
There may be life on other planets or moons but it will be primitive life. The most likely life
forms to exist are extremophiles and Archaea. These organisms are micro-prganisms that
can withstand extreme environments, like thermal vents of Europa’s underground oceans.
They are extremely primitive life forms.
Mars, Titan and Europa all have conditions that enable primitive forms of life to survive
there. Europa’s underground oceans are fantastic places for extremophiles to thrive, they
provide liquid water, energy may be able to be obtained from thermal vents and the
environment is appropriate for several species of extremophiles to live in. The same can be
said for the surface of Titan, which provides water, in the form of ice, and energy in the form
of organic compounds. Extremophiles can adapt to most environments, so they would find
no problem living on the surface of a barren planet.
There is life in every corner of the Earth, even in places scientists never believed possible.
Therefore, it is completely possible for life to exist outside of the Earth.
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: High Achieved
4.
In order to Achieve the student needs to investigate an aspect of astronomy. This involves
selecting and processing a wide range of reliable information related to the astronomical aspect
and the relevant science and explaining the astronomical aspect.
The student has produced a report with the astronomical aspects explained, but with the key
science only briefly mentioned. A wide range of reliable information has been selected and
processed related to the astronomical aspect and the relevant science and sighted by the
teacher.
Examples:
“Carbon is a building block of organic molecules, liquid water is needed to dissolve important
substances and energy can be gained from the Sun or certain chemicals.”
Key science has been described but not explained. Explanation is required for Merit.
“Europa, is one of Jupiter’s moons…Europa is very cold on the surface but deep down where
water melts the temperature may be warm enough for life to survive.”
Astronomical aspects have been explained and therefore this response is at a High Achieved
level.
To reach Merit the science needs to be fully explained.
© Crown 2012
Student 4: High Achieved
Could Aliens Really Exist?
For life of any form, simple or complex, there are a number of key factors that have to
be in place for it to be sustained. For simple life e.g. bacteria or Archaea, there needs to
be carbon source, liquid water and an energy source. Carbon is a building block of
organic molecules, liquid water is needed to dissolve important substances and energy
can be gained from the Sun or certain chemicals. There are extreme environments on
Earth where no complex life could live but where single celled organisms live. These
organisms are called extremophiles and these could be present in other parts of the solar
system where there are possibly even more extreme environments. Extremophiles have
been found in places such as the deep ocean and high alkaline or acidic environments.
These environments could be very similar to some out in space so if they can survive in
the conditions on earth it is likely there will be other life form on planets or moons.
Extremophiles are grouped depending on the type of extreme environment they survive
in e.g. Halophiles for salinity, Alkaliphiles and Acidophiles for high and low pH,
Thermophiles for high temperature, and Barophiles for pressure.
Mars (a planet), Titan, Europa and Enceladus (moons), have all been considered as
places with possible extremophiles.
Mars; is the fourth planet from the sun, it is 1.52 astronomical units (AU) from the Sun.
Mars has a thin atmosphere but very strong winds which cause huge dust storms; these
can last from days up to weeks. Mars has a temperature range of about -133C to +27C,
and there is evidence that there was possibly liquid water on the planet in the past with
the suggestion it may still exist underground. Mars has a very thin atmosphere which
causes any water to freeze. Mars also has a tilt which causes seasons and may mean
that water melts at the poles in summer.
Titan is the largest moon of Saturn and is composed of water ice and rock. It is also the
only moon in our solar system that has a thick atmosphere and surface liquid such as
lakes. The atmosphere and lakes both have lots of methane and ethane. Unfortunately
Titan is also very cold so there may not be much liquid water.
Europa, is one of Jupiter’s moons. It has a thick ice layer of ice about 11 kilometres
deep with probably a liquid ocean underneath. The gravity of Jupiter as Europa orbits
causes movement and friction of the crust resulting in heat which melts the ice at the
bottom of the thick ice layer. It is unlikely that dissolved oxygen would be present in the
water but many species of extremophiles don’t need oxygen to live. Europa is very cold
on the surface but deep down where water melts the temperature may be warm enough
for life to survive.
Enceladas is the sixth largest of the moons of Saturn and also has an icy surface. It
seems as if Enceladus has water on or near the surface. The gravity of Saturn as
Enceladas orbits causes movement and friction of the crust resulting in heat which melts
ice just under the surface. This is resulting in plumes of water vapour, ice and organic
compounds erupting on the surface of this moon. The presence of liquid water near or on
the surface fulfils one of the conditions for life to be present.
If there was to be a discovery of any type of life on those planets and moons though,
they would be simple life. Unlike Earth they are not in the “habitable zone” but as long
as there is liquid water, a carbon source and an energy source there is a chance of life.
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: Low Achieved
5.
In order to Achieve the student needs to investigate an aspect of astronomy. This involves
selecting and processing a wide range of reliable information related to the astronomical aspect
and the relevant science and explaining the astronomical aspect.
The student has produced a report with the astronomical aspects explained but with not a lot of
detail.
A wide range of reliable information has been selected and processed related to the
astronomical aspect and the relevant science and sighted by the teacher.
In order to Achieve the student needs to investigate an aspect of astronomy. This involves
selecting and processing a wide range of reliable information related to the astronomical aspect
and the relevant science and explaining the astronomical aspect.
Examples:
“It could be possible that there is life on Mars because there is evidence, shown by signs of
erosion that water once flowed on Mars. There is also water in the polar caps on the poles and
there may be water underground. Mars is located 1.5 AU away from the sun, so the sun could
possibly be an energy source.”
Astronomical aspects have been explained but are lacking in detail.
To Achieve more securely the science needs to be described and explained.
© Crown 2012
Student 5: Low Achieved
Are there aliens out there?
Introduction
Is there life on other planets or moons? Although other planets and moons don’t have
requirements for complex life, such as plate tectonics, sufficient water, nutrient cycles,
and within the Goldilocks zone, there may be simple life elsewhere in the solar system.
The most likely planet and moons to find simple life on are Mars, Titan and Europa.
Simple life means single celled micro-organisms such as bacteria or Archaea.
Simple Life
Simple life requires very few things in order to survive. The three things they need to
survive are a carbon source, water and an energy source. Carbon forms large molecules
with other atoms such as hydrogen and oxygen. Carbon is found throughout the solar
system. Water is needed for essential chemical substances to dissolve in. An energy
source is needed to keep water liquid and to drive reactions. Energy can come from the
Sun or from other chemicals.
Mars is the fourth planet from the sun and is the most likely planet to have life, apart
from Earth. It could be possible that there is life on Mars because there is evidence,
shown by signs of erosion that water once flowed on Mars. There is also water in the
polar caps on the poles and there may be water underground. Mars is located 1.5 AU
away from the sun, so the sun could possibly be an energy source.
Titan is Saturn’s largest moon and is the moon most likely to host life. Titan has many
organic compounds such as methane and other hydrocarbons which can act as carbon
sources. Titan also experiences wind and rain like we do on Earth except that the Titan
atmosphere is mixture of methane and ethane. Because of this Titan has similar surface
features to Earth e.g. rivers, seas.
Europa is one of Jupiter’s moons and is also likely to host life. It has water, energy and a
carbon source. Carbon molecules are found in the water. Europa would not get energy
from the sun because sunlight could not melt the thick layer of ice on the surface. The
effect of Jupiter’s gravity moves the crust up and down under the ice and warms up the
ice melting it. Therefore Europa could have oceans of water under the thick layer of ice.
Extremophiles
The discovery of extremophiles started in the 1960’s and has challenged scientist ideas
about extra-terrestrial life. Extremophiles show how life can exist in the most
inhospitable places on Earth. They have been found in conditions of high acidity or
alkalinity, very high or very low temperatures, high salinity and extreme dryness. They
are also found deep underground and in deep sea trenches under extreme pressure and
they are able to extract energy from chemical compounds such as hydrogen sulfide.
If life can be found in these sorts of environments on earth then there is no evidence to
say why it wouldn’t be found in similar environments on places like Mars.
Exemplar for internal assessment resource Earth and Space Science 3.6A for Achievement Standard
91415
Grade Boundary: High Not Achieved
6.
In order to Achieve the student needs to investigate an aspect of astronomy. This involves
selecting and processing a wide range of reliable information related to the astronomical aspect
and the relevant science and explaining the astronomical aspect.
The student has produced a report with the astronomical aspect mostly explained, but it is
lacking adequate explanations on key points.
Examples:
“But Mars is just outside the Goldilocks zone and it may have water at the poles or
underground…Mars where there may be water.”
There is a lack of explanation of astronomical aspects which is required for achievement of the
standard.
“But life in extreme environments is found in very simple life such single celled organisms.
Simple life only needs a carbon source, liquid water and an energy source.”
No attempt has been made to explain why these are important.
To Achieve the science needs to be described and explained.
© Crown 2012
Student 6: High Not Achieved
Are there aliens out there?
Introduction
It seems that planet Earth is the only planet or Moon in the Solar System with life
on it. Space probes have flown past other planets but there is no sign of life
anywhere. Also, Earth is the only planet in the “Goldilocks” zone, which is the
right distance from the Sun to have the right temperature on the surface for
liquid water. However, Earth has got some places that are very inhospitable and
surprisingly living things have been found there so maybe there is life elsewhere.
Possible planets and Moons?
Mars is the only planet that may have life. Mercury is too near the Sun and Venus
has thick toxic clouds and is very hot. Jupiter, Saturn, Uranus and Neptune are all
made of gas. But Mars is just outside the Goldilocks zone and it may have water
at the poles or underground. Space probes have found signs of water in the form
of dried up rivers. Seeing that some extremophiles can live deep underground
maybe they can live underground on Mars where there may be water.
Two moons may also have life - Europa and Titan. Europa orbits around Jupiter
and has thick ice all over its surface but there may be liquid water underneath.
Jupiter makes Europa warm which melts the ice.
Titan orbits around Saturn and has thick clouds and lakes of organic substances.
Titan is Saturn’s largest moon and is the moon most likely to host life.
There is no oxygen in the atmospheres of Mars, Europa or Titan so any
extremophiles would have to live without oxygen.
Simple Life
What does life need? It needs all the MRS GREN things, movement, sensitivity,
respiration, growth, excretion and nutrition. But life in extreme environments is
found in very simple life such single celled organisms. Simple life only needs a
carbon source, liquid water and an energy source.
Extremophiles
Extremophiles are the sort of life that may be found on Mars, Europa and Titan.
These are single celled organisms that can be found in many different
environments that are very acid, very cold or very hot, very salty, very dry, deep
underground and under extreme pressure. Extremophiles can even live without
oxygen.
Simple life doesn’t need much so life might be found on other planets and moons
when we finally get there to have a look.