Aziphirael, IAMS, Menion, Dr Jekyll, Naterepasky and Schafer.
Orbital Manoeuvring Vehicle Proposal
Codename: Orson (ORbital Repositioning Satellite Operations Node)
The main aim of this document is to try and collate together as much information and ideas
about building an OMV – Orbital Manoeuvring Vehicle. In essence this will be a proto design
document, looking into various options and as time progresses lay out concrete concepts and
The OMV is a vehicle should be designed with the following objectives:
Boosting satellites from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO)
Recovery of satellites from a variety of orbits.
Boosting satellites that may have entered the wrong orbit due to a launch failure.
Repair, Maintenance and refuelling of satellites.
Possible use to recover external tanks of the shuttle.
If using the modular system maybe using the OMV to test new technologies.
As far as possible the OMV should be built using of the shelf technologies and parts.
However a possible concept is to create a modular system so that parts of the OMV can be
“swapped” out and replaced by new systems that could be used to test new technologies. This can
be technology devised by another company of which we then take a fee, or in house technologies. If
the modular system is used then the following sections will deal with each module in turn.
A module should have defined inputs and outputs. In this way they can be swapped out and
in with minimal ease. The other advantage is that these specifications can then be given to other
companies should they wish to contract us out for experimental services like testing new propulsion
The modular system can be designed with two tiers. The first tier is a structural module. The
basic craft airframe which can be extended. The best analogy for this are the ISS Modules. They are
the basic airframes of the space station. The second tier is the actually functional modules, be it
propulsion, power etc… Again the analogy of the ISS can be used. These modules would be the
experimental and system racks within the ISS. With the OMV for example we could start of with a
basic airframe module which can take one of each functional module. Then if it was decided to
expand so that we want for example two propulsion modules we would add a new airframe module
and then the new propulsion module. This would be useful as well if we decide to sell test services
on the OMV. This way should the experimental module go wrong we still have the originals to go
One of the main things is that the OMV should be able to build itself. It could be possible
to send up new modules and parts and the OMV will be able to with help from the ground build
The airframe of the OMV should be light and strong. Able to withstand micro-meteorite
bombardment. Because at present the OMV is not manned then no consideration need to be given
to create something that is airtight. Standard satellite construction may be possible to be used. The
shuttle external tanks for example are now build using a new Aluminium Lithium alloy that is 30%
stronger but much lighter then the original tanks.
One could base Orson along the lines of the ISS: use a truss structure as a kind of skeleton
and add modular components to it by plugging them into a "spinal cord" power and information
distribution system (it would be a parallel circuit with several main trunks to increase reliability and
serviceability). These modular components would include everything from the engines to the
computer system. This would make Orson very flexible, upgradeable and repairable: simply "swap"
The modules would be boxes/cylinders/spheres etc. with walls comprised of 2 shells of
carbon composite with insulation filling the space between the walls. In, addition the objects would
be wrapped in ceramic-Kevlar cloth for added protection. For added strength a light Titanium alloy
or Aluminium Lithium skeleton can be constructed on which the walls will be mounted. Memory
alloys could be used to "repair" components in which they were embedded i.e. in the
communication antennas etc.
Several connections will be needed to connect the truss with the modules. At least two
power connections types. One would be quite high power for things like the thrusters and main
engines. One would be low power (110 – 240v) to power computers, guidance and other
components on board. Then a network so that the computers in each module and electronics are
able to talk to each other across the network. An off the shelf LAN using Ethernet may be possible
with a network speed of 10 – 100 megabits. The other type of connections would be for the cooling
and/or heating lines which would keep the more sensitive equipment within the correct conditions.
Electric based propulsion is a good first start for the system. For example Arcjet propulsion
could be used since they exist within the market. The following is taken from the website at
THRUSTERS POWER SPECIFIC
Resistojets 100s of watts 300 to 400
Arcjets 100s of watts 300 to 400
Hydrazine kilowatts 500 to 600
Hydrogen 10s of kilowatts 900 to 1,200
Ammonia kilowatts to 10s600 to 800
Gridded Ion Engines watts to 1002,000 to 10,000
Stationary Plasma100s of watts to1,000 to 2,500
Thrusters (SPT) 10's of
Thruster with Anode100s of watts to1,000 to 4,000
Layer (TAL) 10's of
Pulsed kilowatts 1,000 to 4,000
Steady-State 100s of3,000 to 7,000
Pulsed Plasma Thruster 10s to 100s of1,000 to 1,500
Pulsed Inductive Thruster 10s of kilowatts 3,000 to 5,000
Electron Cyclotronkilowatts to 10s2,000 to 4,000
Thruster of kilowatts
Electric propulsion methods are more efficient then chemical propulsion, although they still
use up fuel. Whilst they have high specific impulse they have low thrust. MPD has the highest thrust
available to Electric propulsion. The advantage however is that high specific impulse means that less
fuel is needed to accelerate the vehicle then conventional rockets. This means that the fuel storage
can be smaller or that the fuel will last longer.
Other methodologies do exist but these more experimental. An example is tethered propulsion.
However this proposal could be tested later on as a module which can be swapped in and tested on
The two main thrusters that could be used are MPD and Gridded Ion Engines. Arcjets and
Resistojets are readily available and can be bought commercial. However these are quite small and
designed more for satellite station keeping then the main engines of a craft. The MPD could be
viable in the pulsed version. This also has the disadvantage of being much easier on the cathode
which erodes over time due to the high temperatures of the plasma being ejected. However it does
allow a higher current and power to be discharged through the engine. But this form of the MPD
thrusters does need more materials and a more complicated power conditioning system.
Another important consideration is the fact that the engine should be relatively simple in
terms of parts. This would save weight, lower the cost of the build time and also reduces failures.
They would also be easy to repair.
The type of propellant is also important. A propellant that is storable in space without
complex storage equipment would be useful. Examples are Hydrazine and Ammonia. Hydrogen
could be used but is difficult to store and requires complex cooling. Xenon gas could be used but is
rare and expensive. The pulsed plasma thrusters for example can use solid fuels such as polymers.
MPD Thrusters are more efficient in the megawatt area whilst the Ion Engine can run at the
lower power levels. MPD can work in the pulsed mode but requires different forms. The concept
Ion Engine could be 50cm diameter xenon powered Ion Bombardment Engine.
There are perhaps several main areas that could provide power to the craft. These are:
Batteries and Fuel Cells.
One of the main problems with Solar Panels is that supposedly they are susceptible to radiation
especially in the Van Allen belts which exist between LEO and GEO. However they can be shielded
and the sunlight beamed onto them using mirrors and lens. In reference to Solar Panels, it is
possible to repair the damage cause by the Van Allen belts via heating them up to over 400K. Also if
the Van Allen belt were traversed quickly then the radiation damage may not be too great.
Nuclear power has various problems which are environmental and political at the same time.
Plus the nuclear safe orbit is 700km or greater to allow for a 300 year minimum before the nuclear
reactor re-enters the atmosphere. Fuel Cells and Batteries may not be able to give the power
requirements needed for the propulsion system (In the Kilowatts to Megawatts range). The higher
the power output the better the propulsion system is.
A possibility is to create some kind of dynamic conversion system which converts the heat of
the sunlight into electricity using some kind of turbine system. Have lenses that concentrate the
electricity into the generation system.
The current concept is to use a combination of Solar Panels and a Thermal generating system.
Current power output is approximately 300kw – 600kw. The solar panels can be shield from the Van
Allen belts to some extant. For example using the Stored Concentrator Arrays as on Deep Space 1
missions. Since these have lenses over the solar cells this would stop some of the radiation.
Furthermore it may be possible to create some kind of heating system which can heat the arrays up
to over 400K thus healing the damage. This heating can be derived from the cooling system.
The Power Module will also need to condition the power received from the sources. This
involves stepping up the power increasing the voltages from the power sources, usually low-voltage
DC from solar panels to high kilovolt levels. Commonly called the Power Processing Unit (PPU)
which is a subset of the power management and distribution (PMAD) system.
Current estimates for the size of solar panels to provide the required power is 200 squared
metres. However this estimate could be reduced with the possibility of solar concentrators lenses
and other advanced technologies. Estimated weight of the solar panels is 3.4 tons using Solar
Concentrator Panels at 17kg/Kw. However other panels types may be able to lower weight.
For operations within the shadow of the Earth batteries will store electrical power from the
Solar Panels. These batteries should at least give enough energy to power the electronic and
subsidiary systems. Whilst not necessarily the main thrusters.
Guidance and control is the brains of the OMV. It should be autonomous in the sense that
it would be able to act on its own. The software is able to deal with various problems that will arise.
Guidance and control are able to control the main engines and also the various manoeuvring
thrusters that are needed so that the OMV can pilot through space. A proposal is to use small arcjets
thrusters or normal rockets thrusters – A possibility here is to use micro thrusters which are small
and have high ratio when it comes to thrust to weight values. Off the shelf satellite guidance and
control equipment could be used although again it may need modifications. Plus software would
have to be written. The system as a whole will be a bit more complex since the OMV will be
traversing various orbits with different loads which may act in different way.
The module that allows the OMV to communicate with ground control. This equipment
might be able to purchased from companies that supply parts and equipment to build satellites.
The payload module contains the various pieces of equipment that allows the OMV to carry
out its task. Be it to repair or refuel satellites. To carry satellites from LEO to GEO and so forth. It
could contain robotic arms and docking ability to dock with satellites and send them up into GEO.
The robotics arms allow the OMV to grapple different types of objects and hold them safely whilst
the OMV propels itself to its proper orbit.
The cooling and heating system takes away waste heat from the space craft. Protecting
sensitive components. This waste heat can be used to heat up the solar panels to regenerate them
from Van Belt radiation as well as helping with other elements of the craft that may need heat. The
system would be plugged into the truss umbilical and control the cooling and heating functions of
This is similar to the payload module except that its main task is to help build the OMV. It
can carry out basic repairs and other forms of maintenance on the OMV if it needs to for example
replace parts etc…
In some ways the best analogy would the Robot arm on the ISS. It would need to be able to
traverse the OMV to reach places and to conduct its business.
The solar panels can be modular in themselves. One of the issues is the concept of folding
them to minimise damage. This can be achieved by using memory alloys which are able to
“remember” the shape that are created in. A simple hinge could be created via these alloys. The solar
panels can plug themselves into a module which serves as the umbilical connection to the rest of the
craft, power and cooling is served by the module.
A ground control system would be needed. Such infrastructure could be build and would
become assets that can be used for the SPS/SES. Alternatively it may be possible to buy time using
some of the current control systems that are available throughout the world. One of the problems
that will face the system is the fact that it can only work when it has line of sight to the craft.
Therefore other ground stations may needed around the world to maintain contact. However a
possible work around is to have the OMV as autonomous as possible so that it is still able to
function on its own. Or to have mini satellites deployed so that they can relay the signals from the
ground station. The costs and problems of each method will have to be looked into.
The OMV will need resupply and updates to it. The modular system would allow for the
ability to swap in new modules. The main consumables would be fuel, with possible updates to the
technology of the OMV plus maintenance – spare parts and modules. One area that may need
replacement is the main engine. This could be launched on a relative cheaper rocket such as Pegasus
or Minotaur. Although a RLV would make it much cheaper, for example the X34 which based on
Alternatively a RLV would have to be developed. Although it may be possible to “hitch” a
ride with a rocket that has already got some payload. But may still have some space available. This
may be cheaper and more efficient to do.
The maximum weight cap is in the region of 20 tons. This is the upper limit for such launch
vehicles as the Delta IV and Proton Rockets. Less weight would allow other launch vehicles to be
considered such as the Zenit and Ariane. Mazimum size of the payload to be carried would be also
capped at a maximum of 20 tons.
Items that require fabrication:
One of the main problems that can be foreseen is the fact that the engines will probably
need to be fabricated. Ion Engines do exist although mainly as prototypes. MPD engines exists as
test models and prototypes in several institutions. Their general design however is much easier to
implement the Ion Engines. A further spin off of this is the fact that it may be possible to sell these
engines within the satellite and space probe market if they have been proven in the real world.
Airframe will also need to be fabricate and possibly some areas of electronics for control and
guidance. Off the shelf electronics could be used but it probably recommended to test these to
destruction to make sure that they are up to the rigours of space.
Another question that has to be answered is what kind of legal problems will there be.
Bureaucracy will also mean costs. Such issues include whether such a craft will need a license, some
kind of flight certificate. Handling of toxic substances if for example hydrazine was used as the fuel.
Also what kind of issues are needed to be resolved if a ground station has to be build from scratch.
Whilst the issues may not be insurmountable they will have to check and if there is a problem solve
it. These problems may become more of an issue if a man rating is needed to fly people into space.
3.Detailed Design Concepts:
Below are some of the figures that have been considered within the design of the vessels.
Such considerations include size and power of engines. The electrical power considerations and
optimal mission times.
Sketches of possible designs
4.Future Modules and Technologies:
This section attempts to try and bring together ideas and possibilities, technologies that
could be tested on the OMV at a later date or within its next incarnation. The OMV could even be a
testbed for other companies and institutions technologies.
Different Electric Propulsion:
Test different types of electric propulsion technologies. For example MPD Thrusters. If
these technologies can be proven in space then it will open up the market for these technologies
allowing for commercial spin-offs. For example selling thrusters to the satellite and probe marker.
Using tethers as either a method of propulsion or power generation. Such a system could
allow for different orbital changes and speeds. Minimising fuel consumption. Once again there could
be useful commercial possibilities with the concept of tethers and may be able to reduce costs of
changing orbits and speeds.
5. Estimates for Costs: