This blog is about how we can make large space construction by the way of direct polymerisation composite materials in free space environment (Earth orbit, on Moon surface, on asteroids and in far space).
We are looking for partners
to make a stratospheric flight experiment
The aim: The development of
polymeric material that is curable in free space environment for use as
structural components in large space constructions.
Background: Future space
exploration will require large light-weight structures for habitats,
greenhouses, space bases, space factories and so on. A new approach enabling
large-size constructions in space relies on the use of the technology of the
polymerization of fiber-filled composites with a curable polymer matrix applied
in the free space environment. For example, a fabric impregnated with a
long-life matrix (prepreg) can be prepared in terrestrial conditions and, after
folding, can be shipped in a container to orbit and unfolded there by
inflating. Then the matrix polymerization reaction is initiated producing a
durable composite wall or frame. Using such an approach, there are no
restrictions on the frame size and form of the construction in space and the
number of deployment missions is kept at a minimum.
In free space the material is exposed to
high vacuum, dramatic temperature changes, plasma of free space due to cosmic
rays, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite
fluence, electric charging and microgravitation. The development of appropriate
polymer matrix composites requires an understanding of the chemical processes
of polymer matrix curing under the specific free space conditions to be
Previous studies: Our preliminary
studies of the polymerization process in high vacuum, space plasma and subject
to temperature variations indicate that for specific prepeg preparations the
polymerization process is likely to be successful in free space and that the
composite cured in a free space environment will have satisfactory mechanical
properties. However, the curing processes are sensitive to free space factors
such as high vacuum, flux of high energy particles and temperature variations
Particularly pertinent observations from
our previous work include:
·The evaporation of the active
components can stop the curing reaction and evaporation can cause bubble
formation in the curing polymer matrix and compromise the mechanical properties
of the cured matrix.
·Fluxes of high energy particles in
space irradiation can destroy macromolecules and create free radicals, which
can accelerate the curing kinetics and strengthen the composite.
·Temperature variations change
dramatically the curing kinetics and evaporation process.
(For details see A. Kondyurin, Curing
of composite materials for an inflatable construction on the Moon, chapter in
“Moon. Prospective Energy and Material Resources”, Springer-Verlag, Berlin,
2012; A. Kondyurin, M. Bilek, Ion Beam Treatment of Polymers. Application
aspects from medicine to space, Elsevier, Oxford, 2008; Kondyurin A., B. Lauke,
R. Vogel, Photopolymerisation of composite material in simulated free space
environment at low Earth orbital flight, European Polymer Journal 42 (2006)
2703–2714; Kondyurin A., B.Lauke, E.Richter: Polymerization Process of Epoxy
Matrix Composites under Simulated Free Space Conditions, High Performance
Polymers. 16, 2004, p. 163 – 175;Kondyurin
A.V., Building the shells of large space stations by the polymerisation of
epoxy composites in open space, Int. Polymer Sci. and Technol., v.25, N4, 1998,
Our preliminary studies show, that the
curing process can proceed and a durable composite material can be polymerized under
simulated free space conditions. However in a laboratory environment it is not
possible to simulate accurately the combinations of factors observed in space
in order to assess how the various influences couple. To develop the
appropriate polymer matrix composition for use in a particular free space
environment, the effects of the prevailing free space conditions acting
together must be taken into account. In 2010 we carried out the flight
experiment with uncured composite in stratosphere during NASA balloon mission
and showed, that the effect of cosmic rays on crosslinking of the uncured
composite is significant and well observed. More detailed investigations of the
curing process under real free space conditions, where all these free space
factors act simultaneously during the curing process are required.
Scientific goal of the stratospheric
The goal of the experiment is an
investigation of the effect of the stratospheric conditions on the
polymerization process in the polymer matrix of the composite material.
Stratospheric conditions are expected to have a unique impact on chemical
processes in polymer materials. The unique combination of low atmospheric
pressure, high energy cosmic rays, high intensity UV radiation including short
wavelength UV, diurnal temperature variations and other aspects associated with
solar irradiation has strong influence on chemical processes in polymeric
materials. Since such conditions can not be adequately simulated in the
laboratory, it is difficult to predict the impact on curing chemistry which is
particularly important in designing polymers which could be shaped and cured in
space for large scale structural applications.
The experiment involves expositing a cassette
containing polymer samples to the local environment during the stratospheric
balloon flights. The samples consist of uncured polymer matrix and carbon/glass
fibers. The polymer matrix is activated by stratospheric conditions
(temperature and sun irradiation) and the chemical polycondensation reaction is
initiated. Control samples, which have been cured or partially reacted prior to
the flight will be included in the cassette. After the flight, the samples will
be returned to the laboratory and analysed by spectral, chemical and mechanical
methods. The concentration of active components, the stage the reaction reached
in each composite, structure of the polymer, degradation of polymer
macromolecules, crosslinking, oxidation and mechanical properties will be
analysed. To help understand how the conditions couple, a parallel set of
samples will be exposed to similar vacuum levels, UV light and temperature
variations in laboratory experiments. These samples will be analysed in the
same way as those exposed in the space flights and the results compared.
The cassette holding samples to be exposed in
space has a mass of about 1 kg and dimensions with the cover installed of about
200x100x100 mm3. The total mass of the samples is about 100 g. The
samples will be placed into the cassette before the flight and sealed by a
cover. The cassette is to be placed and fixed on the external side (outside) of
the balloon’s cabin, preferably on the sun irradiated side. The control
cassettes with the same samples will remain on Earth in the laboratory.
During launching the cover of the cassette will
be opened and the samples will be exposed to the stratospheric environment
during the flight. Expected conditions are the following: a pressure of about
1-2 Torr, a temperature on the sunny side in the range of +80…900C
(during day light 12-14 hours) and -70…800C (night time), a solar
flux of 1300 W/m2. The required flight time is 1 day or more.
The temperature, pressure and UV light
intensity at the cassette will be recorded during the mission. For measurement,
the cassette will be equipped with a thermistor, manometer, radiometer and a UV
sensor. The data of temperature, pressure, radiation and UV light intensity
will be recorded and sent to laboratory after landing.
After landing, the cassette with samples and
the records of flight conditions are to be sent to the laboratory for analysis.
The chemically active polymer composition
corresponds to safety rules for stratospheric flights: non-toxic, non-flammable
Preferably, the experiment will be repeated
during some flights because, the flight conditions may be different in
individual flights. The deviation of flight conditions during different flights
(temperature, irradiation exposure, pressure) will be used for analysis of
kinetics of the chemical reactions. The cassette will be loaded with new
samples for each flight.
Managing of the cassette operation and
data recording during flight:
The cassette operation (opening and closing of
the cover) can be done on command from Earth or automatically triggered by a
pressure sensor to correlate with the altitude of the balloon flight.
The temperature, UV light intensity and
pressure sensors can be installed in the cassette or data can be used from
common sensors installed on the balloon. In the second case, the temperature,
UV light intensity and pressure data must be recorded during the whole flight.
The idea of the direct curing in space environment came to
me about 18 years ago. At that time, I was not sure, if it was done or it is
impossible. All these years have been spent to get clear answer: yes, it is
possible, but no, it is not done.
I met these two comments as reaction on my presentations and
publications. People, who are far from space business, say, “it is done, and
even ISS is done by this way!” People, who work in space industry, say, “this
is impossible, but I do not know why?” All of these comments are not true.
During these years, I was carrying out a number of
investigations, including experiments and theoretical calculations. Part of the
results have been published and presented on conferences in different
auditoriums and countries.
First time, a general way of direct curing was discussed in
Russian journal “Plastic mass” (1997, No.8) and republished in English in
“International Polymer Science and Technology”: Kondyurin A.V., Building the
shells of large space stations by the polymerisation of epoxy composites in
open space, Int. Polymer Sci. and Technol., v.25, N4, 1998, p. 78-80.
After that the further results have been published in a
number of journals:
Kondyurin A., G.Mesyats, Yu.Klyachkin, Creation of High-Size
Space Station by Polymerisation of Composite Materials in Free Space, J. of the
Japan Soc. of Microgravity Appl., v.15, Suppl.II, 1998, p.61-65.
Kondyurin A., Kostarev K., Bagara M.V., Polymerization
processes of epoxy plastic in free space conditions, Paper IAF-99-I.5.04, 50th
International Astronautical Congress 4-8- Oct., 1999, Amsterdam, The
Briskman V., A.Kondyurin, K.Kostarev, V.Leontyev,
M.Levkovich, A.Mashinsky, G.Nechitailo, T.Yudina, Polymerization in
microgravity as a new process in space technology, Paper № IAA-97-IAA.12.1.07,
48th International Astronautical Congress, October 6-10, 1997, Turin Italy
Kondyurin A., High-size space laboratory for biological
orbit experiments, Advanced space research, v.28, N4, 2001, pp.665-671
Kondyurin A., Kostarev K., Bagara M., Polymerization
processes of epoxy plastic in simulated free space conditions, Acta Astronautica, vol.48, N2-3, 2001, pp.109-113
Briskman V.A., Yudina T.M., Kostarev K.G., Kondyurin A.V.,
Leontyev V.B., Levkovich M.G., Mashinsky A.L., Nechitailo G.S., Polymerization
in microgravity as a new process in space technology, Acta Astronautica,
vol.48, N2-3, 2001, pp.169-180.
Kondyurin A., Lauke B., Polymerisation processes in
simulated free space conditions, Proceedings of the 9th International Symposium
on Materials in a Space Environment, Noordwijk, The Netherlands, 16-20 June,
2003, ESA SP-540, September 2003, pp.75-80
Kondyurin A., B. Lauke, I. Kondyurina and E. Orba, Creation
of biological module for self-regulating ecological system by the way of
polymerization of composite materials in free space, Advances in Space Research, 2004, v. 34/7, p. 1585-1591.
Kondyurin A., B.Lauke, E.Richter: Polymerization Process of
Epoxy Matrix Composites under Simulated Free Space Conditions, High Performance
Polymers. 16, 2004, p. 163 – 175.
Kondyurin A., B.Lauke: Curing of liquid epoxy resin in
plasma discharge, European Polymer Journal. 40/8, 2004, p. 1915 – 1923.
Kondyurin A., B. Lauke, R. Vogel, Photopolymerisation of
composite material in simulated free space environment at low Earth orbital
flight, European Polymer Journal 42 (2006) 2703–2714.
Kondyurina I., A. Kondyurin, B. Lauke, L. Figiel, R. Vogel,
U. Reuter, Polymerisation of composite materials in space environment for
development of a Moon base, Advances in space research, 37, 2006, p.109-115.
A. Kondyurin, B. Lauke, R. Vogel, G. Nechitailo, Kinetics of
photocuring of matrix of composite material under simulated conditions of free
space, Plasticheskie massi, 2007, v.11, pp.50-55.
A.V.Kondyurin, G.S.Nechitailo, Composite material for
Inflatable Structures Photocured under Space Flight Conditions, Cosmonautics and rockets, 3 (56), 182-190, 2009.
A.V.Kondyurin, L.A.Komar, A.L.Svistkov, Modelling of curing
of composite materials for the inflatable structure of a lunar space base,
Journal on Composite Mechanics and Design, 15 (4), 512-526, 2009.
A.V.Kondyurin, L.A.Komar, A.L.Svistkov, Modelling of curing
reaction kinetics in composite material based on epoxy matrix, Journal on
Composite Mechanics and Design, vol. 16, no. 4, pp. 597-611, 2010.
A. Kondyurin, Direct Curing of Polymer Construction Material
in Simulated Earth’s Moon Surface Environment, Journal of spacecraft and rockets, V. 48, No. 2, pp.378-384, 2011.
A.V.Kondyurin, L.A.Komar, L.A. Svistkov, Modeling of the
kinetics of the curing reaction of the epoxy binder-based composite material,
Nanomechanics science and technology: An international journal, vol.2, issue 2,
A. Kondyurin, L.A. Komar, A.L. Svistkov, Combinatory model
of curing process in epoxy composite, Composites, part B, 43, 616–620, 2012.
The recent experiment has been done on the curing in stratosphere.
First time, it was shown, that cosmic rays play role of additional hardener for
the polymer. Space makes polymer harder. This real flight experiment supported
previous laboratory investigations and made me sure, that it will work in real
If you are interested in and do not have subscription for
these journals, please, ask me, I will send you a copy.
The temperature in space is tricky. Usual imagination, what
we have on Earth, does not work there. Imagine: there are no walls, furniture,
ground, neighbours, friends and wind (air) surrounded your body. Temperature
depends on the irradiation from the Sun and on internal sources. All bodies
irradiate following Stefan–Boltzmann law.
If no irradiations from neighbours,
your temperature goes to absolute zero, well, not zero, because of space irradiations.
But anyway, it comes to very low temperature; the space flight measurements
give temperatures about -150 C. If you are irradiated by the Sun, your sun-side
will be heated up in dependence on reflectivity of your surface,
thermocapacity, thermoconductivity and geometry of your body. Very quickly you
start to feel, that one side of you is burning (can be +150 C and more), while
the other side is still frozen. You will want to turn. If you turn quickly
enough, your temperature will be more or less steady. So, the rotation of the
body is very important.
Now let’s remember, how the chemical reaction
depends on temperature. At first approximation, the rate of reaction follows Arrhenius
law: the rate increases with temperature. Usually, the curing system is
selected to be non-reacting at storage temperatures so, that uncured material
can be kept in container at transportation without the reaction. Therefore, the
temperature at curing should be higher than on Earth and at transportation.
There are some ways to get it. First of all, rotation of the
construction side by side to the Sun should be so, that each part of the
construction will be heated enough to be cured completely. It does not need
massive efforts, because no friction there, and if the construction is
accelerated it will rotate forever. You have to be smart enough to calculate
the rotation speed and direction. It can be calculated, measured, compared with
experiments on orbit. The regime of rotation can be optimised to get complete
curing in all sides and parts of the construction.
But what can you do on the Moon or on an asteroid? You
cannot rotate the Moon of asteroid as we want. If you are settled down on
equator of the Moon, you can expect heating enough with the turning of the
Moon. But if your construction has to be placed on polar, what is more likely
because of found water there, there is no way to get a heat enough. You have to
heat it with internal sources, for example, with internal electrical heaters.
And you have to be ready to spend a lot of energy during curing reaction. It is
not a huge amount of energy: ISS astronauts spend a comparable amount of energy
to support life there. The construction can be heated partially: sector by
sector, that can decrease an amount of power, you have to apply.
Another way is to use photocuring reaction. There are
compositions that can be cured under UV light. That’s nice way if you need to
cure quickly, on command after storing long time in the container. In such
case, the curing reaction is not so sensitive to the storage temperature, while
the rate of curing anyway depends on temperature. Such photocuring systems can
be suitable for repairmen set. But the photocured materials have usually lower
mechanical strength, lower radiation stability, shorter life-time and narrower
diapason of exploitation conditions, than thermocured materials. These two
kinds of materials (photocured and thermocured) are specialised for different
constructions. You can choose one of them for particular construction and
However, there is a serious problem with the temperature in
space: thermostresses. This problem needs attention. Usually, on Earth the
prepreg (uncured material) is placed into curing oven, heated slowly with
optimised rate of the temperature increase, cured at uniformly distributed
temperature, and cooled slowly. The heating/cooling process is optimised to
avoid the thermostresses in the construction. In space, when the construction
is irradiated from one side, the Sun irradiation creates a temperature
gradient. The curing reaction follows to the temperature gradient in the
construction. Therefore, the different parts of the construction will be cured
at different temperature and will keep memory of the temperature gradient. When
the cured construction changes an orientation, the temperature gradient changes
and it generates the stresses. As higher temperature gradient is at curing, as
higher stresses appear. The stresses deform your construction and decrease the
mechanical strength of the construction.
Because no one large curing oven with temperature
stabilisation is installed in Earth orbit, where you can put your construction
for precise curing, the temperature regime of the construction should be
precisely calculated and the flight regime should be optimised to get
completely cured material of the construction without significant stresses.
Free space plasma, deadly space
irradiations, burning Sun light. Who can live there? What material can survive there? For how long? – Hopeless questions. That’s enemy environment for all
All materials, including
polymers, degrade in space environment under high energy cosmic rays, Sun wind,
atomic oxygen of residual Earth atmosphere (if Low Earth Orbit). Since first
space flights, engineers worry about degradation of the materials used for
space ships, satellites, stations. A number of experiments have been done,
when different kinds of materials were exposed on Low Earth Orbits. Then the
materials were delivered on Earth, to laboratories for an investigation. The
structure changes in all polymer materials have been observed, described,
calculated and simulated in laboratory experiments.
First of all, this is an effect
of etching. The materials disappear with time: layer-by-layer. You can find a rate of etching in literature for different kinds of materials. There are
handbooks, database, standards and recommendations how to choose a right
material based on mission, orientation, lifetime and functionality of materials
in particular space construction.
At second, the materials become
brittle, cracked, and finally broken under space conditions. The molecular
structure changes significantly: polymers become crosslinked, depolymerised and
oxidised in dependence of kind of polymer. All these effects in polymers can be
observed in laboratory under plasma and high energy particles. The chemistry of
these processes is based on generation of free radicals, when a high energy
particle hits a macromolecule and forms free radicals. The free radicals are
very active and start to react with neighbour macromolecules. These chemical
reactions transform the initial macromolecules dramatically.
The same radiation effects are observed in macromolecules when uncured polymer with liquid matrix is exposed in UV light, g-irradiation,
X-ray beam, plasma and ion beam.
At first, the etching rate is higher. The uncured polymer degrades quicker than the hard polymer. We measured it. But the difference is only 2 times. Is it significant? Yes, for first two-three hours. But then the polymer becomes hard and stays 15-20 years. Therefore, the contribution of high etching rate, when the polymer was liquid, is neglectable in comparison of low etching rate at the rest of life.
At second, the radiation damaging of the macromolecules is the same. The generated free radicals in matrix can
cause two kinds of reactions: crosslinking and depolymerisation. If right
composition is selected, the crosslinking reactions proceed and the polymer
matrix becomes hard. The same effect as in curing reaction, but without any
hardener! Therefore, the free space environment can play a role of additional
initiator of the crosslinking reaction.
"The space makes polymer hard", as the
journalist wrote about our investigations. That’s true, in the case of uncured
composite the enemy space environment helps us to get durable material. Let’s
use this help smartly.
Well, let’s consider the problems of polymerisation in
space: first of all is vacuum.
Low pressure of free space environment is a problem for all
materials, constructions and human during a space flight. This is unusual in
comparison what we have on the “bottom” of our air “ocean”.
At first, the residual gases can inflate the shell of the
construction shortly after launch, when the container with folded shell is
lifted to space. The inflation pressure is very low, if outer pressure becomes
neglectable. This was a reason of some failed space flight missions when large
shell was inflated in Earth orbit, but the uncontrolled inflation broke the
shell. The inflating pressure is close to vapour pressure of cured (hard)
polymer materials, which always contain some dissolved gases, low molecular
fractions and residual solvents. The presence of residual gases is so
dangerous, that the polymer shell can inflate spontaneously after opening of
What will be, if a liquid resin with high vapour pressure will
be placed into the hermetic shell? Explosion. This is why most projects on
inflation space construction with uncured material inside are not realized. No
one of material experts in space agencies agrees to sign permission, that the
shell with liquid resin inside will be deployed under control.
Can we manage it? Yes, we can.
The prepreg with liquid resin should be placed on external
side of the inflating shell. In such case, the evaporation of liquid resin will
be into space. The inflation process of the shell remains dangerous due to
shell vapour pressure, but with special ventilation we can decrease the
pressure caused by evaporation of low molecular components from the shell
material. And the high vapour pressure of the uncured resin will be not important
for the inflation.
You can ask me:
- wait a minute, it means, that the uncured liquid resin
will be placed directly into space?
- But the resin components will evaporate and disappear with
time. Nothing will remain for curing!
- Yes, if a composition of the resin is wrong. Some people
from ESA tried it, failed and said: “curing in vacuum is impossible”. However,
if the composition is right, the evaporation of components is not a problem.
How can we select a right composition?
Look, if you put a glass of water in vacuum chamber and pump
it, after some time you will see, the water evaporated completely. If you put a
glass of ethylene diamine (the hardener for epoxy resin) into vacuum chamber
and pump it, the ethylene diamine will evaporate too. However, if you look at
the door of vacuum chamber, you can see a rubber O-ring. It is used for hermetisation
of the vacuum chamber door to prevent air coming. This O-rig does not disappear
after long pumping at extremely low pressure and temperature. You see, there
are soft substances that can survive in vacuum. Actually, all materials
evaporate in vacuum including metals, the question is: how fast? We must select
substances suitable for the curing (active) and survival in low pressure (slow
To estimate the dangerous of evaporation, we have to
consider a curing reaction of the polymer matrix together with evaporation. In
literature you can find plenty information about kind of curing reaction, some
of active compositions are certified by space agencies to be used in space for
construction materials. All of these materials consist of minimum two
components: resin and hardener. The reaction of polycondensation is mostly used
for curing of such kind of materials. It means, that the ratio of resin and
hardener is usually optimised to get durable composite after curing. If one
component is lost, the composition remains uncured and the material lost
Therefore, the right composition should provide low
evaporation rate for both active components: hardener and resin, and the rates
of evaporation should be similar for all active components.
The second problem is cavitation. When uncured liquid
composition contains a lot of low molecular fractions (it does not matter, if
they are active or not) and these fractions evaporate fast, the composition
becomes bubbled in vacuum. These low molecular fractions evaporate too fast and
the vapours are collected into bubbles. If the composition becomes harder with
time, the bubbles cannot move to the surface, stop and form foam. You can see
it, if you buy liquid polyurethane in nearest tool shop and make polyurethane
foam. Similar foam was observed in NASA space experiment during space flight
and they said: “curing in vacuum is impossible”.
Therefore, the right composition should not contain low
molecular fractions which can make bubbles and foam in vacuum.
If the composition does not break the curing reaction and
does not give a foam in vacuum, it can be cured in space. That’s just right
selection based on knowledge of the evaporation rates, composition components,
curing kinetics and some experience. We have found and tested some compositions
up to 10^-5 Pa pressure. They are not expensive and not rare. Some of them in
cured form are certified for space constructions can be used now.
If pressure becomes lower than the vapour pressure of the
components (10-100 Pa for liquid epoxy resins, for example) and the evaporation
has been started, a following decrease of the pressure does not play a role.
For example, if the pressure in Low Earth Orbit is 10^-5-10^-7 Pa (while the
pressure near spaceship depends on sun irradiation, how long is the ship in the
orbit, material of the ship walls and so on and it is usually higher than the
pressure far from the ship), the evaporation will have similar effect on the
curing material as in deep space, when the pressure can be 10^-11 or lower (if
no one has been there and did not put his gases, I mean evaporation).
Therefore, the compositions tested in Earth orbit can be used on Moon, on
asteroids, in Jupiter’s orbit and in another galaxy.
So, a curing of liquid composition in vacuum is not a
problem, while some official referee of my project in Europe said: “that’s
impossible!” and rejected the project.
Project:”Large-size antenna dish, shield and frame of space station by the
way of polymerization of composite material on Earth orbit in free space
The main goal of the project is the development
of the polymerization processes of polymer composite materials in free space
environment and the creation the technology for large-size constructions
on Earth orbit.
The size and mass of modern space
constructions (antenna, space satellite, space station or space base) sent to
the Earth orbit are limited by possibility of a launch vehicle. The large-size construction can be created by the use of the technology
of the polymerization of fibers-filled composites and a reactionable matrix
applied in free space or on the other space body when the space construction
will be working during a long period of time. For example, the fabric
impregnated with a long-life matrix (prepreg) is prepared in terrestrial
conditions and, after folding, can be shipped in a container to orbit and kept
folded on board the station. In due time the prepreg is carried out into free
space and unfolded by inflating. Then a reaction of matrix polymerization
initiates. After that, the artificial frame can be fitted out with the
apparatus or used for any applications.
In this case, there is no limitation for size
and form of the space construction, there is no necessity for some launch vehicles for
the creation of high-size space construction.
However, conditions of free space
have a destructive influence on polymer materials and especially for uncured
polymer matrix of composite. In the free space the material is treated by high
vacuum, sharp temperature changes, plasma of free space formed by space rays,
sun irradiation and atomic oxygen (on low Earth orbit), micrometeorite fluency,
electric charging and microgravitation. Our preliminary studies of
polymerization process in high vacuum, space plasma and temperature variations
showed that the polymerization process is available in free space under space
factors and the composite cured in simulated free space environment has
satisfied mechanical properties.
The present project includes:
- Investigation of the polymerization process and
structure of selected composite material in simulated space environment;
- Test of polymerization of selected composite
material during space flight;
- Development of large-size mirrors, antennas (some km
diameter) and frame of space construction (for example, cylinder of 100
length and 10 m diameter) on Earth orbit by way of curing of polymer composite materials in
We have 55 years space flight history today, but we are
still here, near Earth. Dreams on exploitation of other planets, asteroids,
stars are as far as 55 years ago. Prospective programs of all space agencies do
not include real plans for human mission far space. Only talks, talks, talks. Why?
Why are we anchored on Earth? Why do we only dream about other planets and make movies?
The Moon is the nearest celestial body to our Earth. Man
first visited the Moon in 1969. Why it was stopped? You say, it is too
No. The problem is that we can do nothing there: in space,
on Moon, on Mars. Look our “modern” spaceships. Could you live in “fish-box”
some years? Could you develop mining on asteroid if your “home” is 3x6x6 meters, where you
can take out your hermetic spacesuit?
No. We need large construction in space. In order for
long-term human missions to be possible, large pressurized construction is
Let’s look what we have and what do we plan now. The 6.65 m3
pressurized crew compartment volume realized in Apollo program. MIR space station had 350 m3 pressurised volume. Completed ISS after
more than 10 years of building has 109 m length and total volume of 837
What do we need for real long-term space mission? Hundreds
of cubic meters for one crewmember are required for living area, working area,
greenhouse with sufficient plants and animals for food, air and water recovery
and storage. We cannot go further without significant improvement of living
space in space.
It is real barrier for space programs, space missions, space
industry, space exploitation. No way further without breakage of this barrier.
The projects discussing such large metal constructions
delivered from Earth were proposed since the first flight on Moon. However,
this method is not realistic: such large construction cannot be launched from
Earth (too big mass and size). Large construction cannot be landed on the Moon
(too big inertia). Such large constructions should be extremely durable to
survive under huge accelerations at start and at landing (if landing on Moon or
Mars). Building of large construction in space requires a long presence of
workers (workers need pressurized cabins, life support system, water, food,
that needs large construction to deliver and to keep it), delivering of
separate blocks to one place with landing rockets (accuracy of landing in some
meters is too complicate, or it needs Moon’s/Mar’s tracks to collect all landed
blocks). Experience with building of ISS (International Space Station) showed,
that the module building is extremely expensive, need much more launches and
time and resources, than planned before, it takes years to finish. But the
volume of whole ISS is enough only for 1 crewmember for far space mission!
You can say: robots will build the construction. Yes. Sure.
I agree, in next 100 or more years. No one house has been built by robots
on Earth by now. No one man lives in such house. It is too complicate. But
space environment is much more complicate, than your smooth land with developed
communications, roads, suppliers.
Therefore, a large construction in space should be built
There is only one way to get sufficient volume of the
pressurized crew compartment: an inflatable construction. The soft shell of
inflatable construction can be prepared on Earth, folded and transported in
small container to space. Then the shell is inflated to a sufficiently bigger
volume than the container. The shell materials should be soft to unfold easy
and light to provide low mass.
Space agencies have an extensive experience in inflatable
constructions. The history of inflatable space structures started from the
"Echo", "Explorer", "Big Shot" and
"Dash" balloon satellites in the 1960s. Based on success of the
balloon satellite flights new projects utilizing inflatable structures for
antennas, reflectors, Lunar and Mars houses and bases, airlocks, modules based
on light polymer films were proposed from that time. Some of inflatable
structures based on new materials were successfully (and sometimes unsuccessfully)
tested in real space flight.
However, inflatable structures haven’t had a wide
application in space exploration because of high risk of damage of the soft
inflatable shell. Of course, the shell could be made of thick multilayers
(Spacehab project), but the shell becomes heavy and the advantages of
inflatable construction disappear.
The use of inflatable construction in space environment
needs a rigidization of the construction wall after inflating. Since the first inflatable
constructions flights, several methods of rigidization have been discussed:
rigidization due to chemical reaction of a soft polymer matrix by thermal
initiation of reaction, by UV-light initiation and by inflation of gas
reaction; mechanical rigidization due to a stressed aluminum layer in the
deployed shell; foam inflation; passive cooling below Tg of material;
evaporation of liquid from gel. In some cases a combination of hard and
rigidizable structures was developed. All of these methods were tested in Earth
laboratory experiments. Only one real mechanism of rigidization was
successfully tested in real space conditions - Aluminum stressed layers.
However, this method is not suitable for large space construction.
The best way of rigidization is a chemical reaction in
polymer matrix impregnated by fiber filler, which gives a durable composite
material. These materials were tested under superior conditions including real
space flight experiments. These materials are used for a wide number of space
constructions now on Low Earth Orbits (LEO) and Geostationary Earth Orbits (GEO).
These materials have long life-time (up to 20 years) under free space
conditions and certified in all space agencies. Therefore, the chemical
reaction rigidization process is the best method to be used!
For the creation of the construction frame, the fabric
impregnated with a long-life matrix (prepreg) is prepared in terrestrial
conditions, which, after folding, can be shipped in a space ship to the Earth
orbit, Moon, Mars or other planet. The curing process should be slow to keep
the prepreg soft. In space the prepreg is carried out and unfolded by, for
example, inflating an internal bag. Next the chemical reaction of matrix
curing should be initiated. The reaction can be initiated with high temperature
or UV light irradiation. The required temperature for the chemical reaction can
be achieved with Sun light irradiation or with internal heaters inserted in the
prepreg. If the curing reaction requires UV light for the initiation, the sun
light or UV lamps can be used to illuminate the prepreg. After complete curing
the construction can be pressurised, fitted out with the apparatus and life
However, the curing technology of the composite material in
space is not yet developed. The curing process in terrestrial environment is
different than it will be in space. The prepreg cannot be placed in thermobox
for precise temperature cycle, as it is used on Earth. The prepreg cannot be
kept at Earth atmospheric pressure to prevent evaporation of active components.
The composite material cannot be tested after curing to be sure in strength and
exploitation characteristics of the material as it is usually done for
construction materials on Earth. The curing technology in space will use
different principles of composition, curing, testing as on Earth. It should be
well developed and proved.
The main factors of space environment are high vacuum, space
plasma (different kinds of irradiation, cosmic rays, Sun wind, atomic oxygen
flux on Low Earth Orbit), sharp variation of temperature, microgravity (in
orbit flight). All these factors influence on the curing process.
We have investigated the curing process in different
compositions: under high vacuum, plasma and ion beams, in wide temperature
variations. We found curable compositions for space environment. We found, that space plasma will help us to cure the construction wall. We tested mechanicals strength of the materials, that were cured under simulated free space conditions. It works!
Conclusion: a curing in space is possible.
What is now? We need to test our composition in real space
flight and then we can build large construction in space. A building of 10 m diameter and 80 m length after one launch is enough for your space factory?