Hello! My name is Nicol Caplin and I'm a Research Fellow in Astrobiology at ESA
I'm going to answer some of your questions about this exciting field of space science.
When astrobiologists talk about the limits of life we're referring to
the known boundaries of life on Earth, so life as we know it can survive.
These physical and chemical conditions include temperature, radiation,
water availability and toxicity of metals in the environment to name a few.
We all know that different living organisms have different requirements for these things.
For example, you and I need around 8 glasses of water a day,
but that's going to be quite different for, say a fruit fly or a cactus.
Did you know that there are some life forms that can
actually survive periods of time without water?
You might think of a camel with its water storing hump on its back,
but if you think smaller, much smaller, there are some microorganisms that can survive
complete desiccation and this means that they can be totally dried out and go into a dormant
or sleeping state. They can wake up again once they're hydrated with water.
Microbial life dominate all sorts of extreme environments.
The current world champion for upper temperatures for life on our planet is a
strain of archaea found in a hydrothermal vent. It's known as strain 121.
Any idea why it was called that? Maybe you already guessed, it is able to
survive and even reproduce at 121 degrees Celsius and it's this sort of
life, which we call extremophile life, that astrobiologists are interested in
to support theories of Panspermia, where
microorganisms might have needed to survive long trips around our galaxy on
comets or asteroids to go and bring life to planetary bodies perhaps including
our very own home planet. In the same way that life is transferred around
different habitats on planet Earth you might like to consider that space can
also act as one big system and life is a part of it and in some ways that's already true.
Have you ever seen a shooting star?
Meteor showers are common and can be observed from many parts of the world.
We already know that there has been and still is an exchange of materials
between Earth and Mars because we have evidence from Martian meteorites that landed here.
Space is such an active place, so it's quite possible
that some life-forms hitched a ride from one
planet to another; the difficulty is that such arrived would be impossible for you
or me because of the extreme conditions. That's why astrobiologists are studying
many types of microscopic extremophiles to test out their limits and to see if
maybe life was imported here from somewhere else in space.
If we're planning on exploring other planets or icy moons that we think may
contain or once contained life then how do we make sure that we don't
contaminate it? It is a very important thing to consider.
The Committee on Space Research, COSPAR, has formulated planetary protection policy to define
different destinations in space and allocate them with appropriate levels of protection.
For example, the Sun is in a category which says it's not of interest
for life detection missions so we don't have to put in special measures to make
sure that we're not going to contaminate it, but it's a different story for Mars
or other planets we think might harbour life.
ESA has adopted this policy and
acts on behalf of its Member States to ensure that the requirements are met for
all missions the agency is flying to or contributing to by employing the use of
clean rooms for our spacecraft and following strict sterilization protocols
we can minimize the risk of contaminating other places and explore
space in a considered way.