Please be advised that this website has been archived and will no longer be updated. The 20 chapter technical paper and the business plan is only in its first draft and is therefore rendered obsolete. There have been many changes to the design and direction of the paper.

For a detailed treatment of our space concepts as High School S.T.E.M. projects, please visit: http://www.stemfortheclassroom.com

The Management

Space Trucking

With a Hat Tip to the band Deep Purple.

We left the last diary and our home away from home up and running and ready to be occupied. Personnel should be coming and going between the Spaceport in New Mexico and our City In The Sky, the Low Earth Orbit Station (LEOS) and its suburbs, the Low Earth Orbit Science Stations (LEOSSs).

However, the space stations are lacking one vital ingredient that we will fill in today. Just like an aircraft carrier, a busy city needs busy vehicles to make the whole ballet work.

Also, just like aircraft carriers, several different types of vehicles will be used for all the different types of missions needed. Paradoxically, our vehicles will also have one thing in common: they are all trucks in space.

You know the drill.

Crew Module (CM)
  • Dimensions of one-half a habitation module (as described in the previous post)
  • Weight range of no more than one-half of a habitation module
Orbital Utility Vehicle (OUV)
  • Dimensions of about one fourth a habitation module
  • Uses a hypergolic fueled Reaction Control System (RCS)
  • Carries either a CM or up to one (1) Skylon payload
Orbital Transfer Vehicle (OTV)
  • Dimensions of a standard third stage rocket
  • Uses an RL10B-2 Rocket Engine with an extendable nozzle
  • Carries either a CM or up to one (1) Skylon payload
GEO Transfer Vehicle (GTV)
  • Dimensions that is larger than a 3rd stage rocket
  • Uses on RL10B-2 Rocket with an extendable nozzle
  • Pop up RCS Quads
These powerful tools will be used to shape the destiny of our space program.

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No one vehicle can do every job in space. This has been true for a very long time. Not to stretch the aircraft carrier analogy too far, but just like an S-3 is better suited at hunting submarines than an F-14, some of our space vehicles will need to be specialized in the same way.

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Crew Module (CM)
The crew module is exactly what the name implies; a place for the crew to eat, sleep, work, etc. in the hostile environment of space. The CM will have the following specifications:
  • Dimensions of 4.0 m (13.12 ft) in diameter by 4.4 m (14.44 ft) in length
  • Weight range of 7,265 kg (16,106 lbs) to 7,533 kg (16,607 lbs)
  • Uses batteries for electrical power (50-day duration between battery recharges)
  • Crew size range of 5 to 24 people
CM component description:
  • Structure: 2219 T87 Shell, 2219 Y87 micrometeoroid shield, insulation, fluids, heat exchanger, accumulator, airlock, docking port, etc.
  • Crew Systems: Food, medical, clothing, hygiene, crew weight, EVA suits, PLSS, etc.
  • EC/LSS: Cabin pressurization, O2/N2, H2O, waste management, etc.
  • Electrical Power: Batteries, regulators, junction boxes, wires, cables, power distribution, etc.
  • Communications: TV, audio, antenna, etc.
  • Instrumentation and Control: Displays, controls, wiring, lighting, instruments, etc.
  • Misc. Equipment: Maintenance equipment, etc.
  • Contingency: Emergency reserve of O2/N2, H2O, food, etc.
The CM will consist of two (2) levels. The top level (left, in the image below) is command and control; the bottom level (right, in the image below) is for the airlock, berthing, lav, recreation, etc.

 

The crew always consists of one (1) pilot and two (2) PRM operators. That leaves between 3 and 21 people for various missions. Included is a minimum of three (3) EVA personnel, if operating in a pure O2 environment.





There is a standard Skylon docking port on top of the CM.

 

The two (2) standard habitat module EC/LSS systems are used here. The systems are positioned adjacent instead of opposite of each other.

 

Food storage, food preparation, showers, etc, are all located in the bottom portion of the CM. The bottom is also used for EVA prep.

 

The CM weight can be calculated using the following constraints:

Minimum Crew:
  • Crew Size: 5
  • Structure: 2,265 kg (4,774 lbs)
  • Crew Systems: 2,166 kg (2,728 lbs)
  • EC/LSS: 1,888 kg (4,163 lbs)
  • Electrical Power: 94 kg (208 lbs)
  • Communications: 237 kg (523 lbs)
  • Instrumentation: 136 kg (301 lbs)
  • Control: 44 kg (96 lbs)
  • Misc. Equipment: 58 kg (128 lbs)
  • Contingency: 644 kg (1,419 lbs)
Total Weight: 7,533 kg (16,607 lbs)

Mission Duration: 50 days

Maximum Crew:
  • Crew Size: 24
  • Structure: 2,265 kg (4,994 lbs)
  • Crew Systems: 2,891 kg (6,374 lbs)
  • EC/LSS: 920 kg (2,027 lbs)
  • Electrical Power: 94 kg (208 lbs)
  • Communications: 237 kg (523 lbs)
  • Instrumentation: 136 kg (301 lbs)
  • Control: 44 kg (96 lbs)
  • Misc. Equipment: 272 kg (600 lbs)
  • Contingency: 619 kg (1,365 lbs)
Total Weight: 7,265 kg (16,016 lbs)

Mission Duration: 2 days

The CM will have a Skylon attach point installed at the bottom to attach it to various vehicles.

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Orbital Utility Vehicle and Accessories
This vehicle is the workhorse around the space stations. It uses hypergolic fuels for the Reaction Control System (RCS), which is used to maneuver in space.

The OUV will have the following specifications:
  • Dimensions of 4.0 m (13.12 ft) diameter by 2.2 m (7.22 ft) in length
  • Empty weight of 1,000 kg (2,205 lbs)
  • Gross Weight of no more than 5,000 kg (11,023 lbs)
  • Uses UDMH fuel for the RCS (weight to be specified at a later date)
  • Uses Nitrogen Tetroxide plus 25% Nitric Oxide (MON25) oxidizer for the RCS (weight to be specified at a later date)
  • Uses Gaseous Helium (GHe) [stored as Liquid Helium (LHe)] for propellant tank pressurization (weight to be specified at a later date)
  • Uses batteries for electrical power (50-day duration between battery recharges)
  • Carries either a CM or up to 14,742 kg (32,500 lbs) of cargo
The OUV will also come with various accessories.

 

The OUV is carried aboard the Skylon intact and fully fueled. It usually will carry a CM along, as well as an airlock.

The RCS quads will be retracted and stowed during the Skylon ride into space so that the OUV can fit in the Skylon payload bay. They will be extracted when the OUV arrives at its destination in space. The quads can be retracted again if the OUV ever needs to be returned to earth.

The Portable Remote Manipulator (PRM) has 2 sets of articulating robotic arms, each with three (3) arms the length of 3.7 m (12.14 ft) and weigh no more than 2,000 kg (4,409 lbs). Standard docking ports are attached at either end.

The Orbital Work Tray (OWT) is a habitat module that is cut in half lengthwise and exposed to space (looks like half a cylinder). Standard docking ports are attached at either end. The tray is used to store tools, parts, MMUs, etc., that is used for maintenance/repair of satellites, spacecraft, etc. OWT weight should be no more than 3,000 kg (6,614 lbs).

The OUV will carry several different types of payloads.

 

The OUV can be flown remotely by the pilot in the LEOS. It can be outfitted with a PRM and operated remotely (again, in the LEOS) to dock and undock modules to itself.

The OUV can also have a CM attached to carry personnel, and a CM/PRM/OWT combination to do maintenance/repair.

The OUV is flown remotely by the pilot aboard the CM (this is the flight procedure that the Skylon employs). The same is true with the PRM operators; they operate the PRM remotely using instrumentation located inside the CM.

OUV Missions:
  • Space Tug. An OUV with an PRM can be used to move habitat/logistics modules around, assist other spacecraft, etc.
  • Life Boat. An OUV with a CM is attached and left to a space station. The CM can hold 24 people for 2 days, so three (3) OUV's docked to the LEOS at various locations could theoretically be used to abandon the space station.
  • Transportation. An OUV with a CM can be used to ferry scientists and other personnel back and forth between the LEOS and the LEOSS's. It can also be used as a way to inspect the space station without conducting an EVA.
  • Satellite Placement/Maintenance/Repair. An OUV with a CM/PRM/OWT can reach close by satellites that are in need of repair and/or maintenance.
There are certainly other missions that that can be used by this versatile vehicle. These missions will be developed when the our plan is implemented.

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Orbital Transfer Vehicle
This vehicle has a cryogenically fueled engine that will be used to change its orbit. It can place satellites in orbits with altitudes as high as an equatorial Semi Synchronous Earth Orbit [SSEO, or 20,200 km (12,552 miles)].

Unfortunately, while it does have enough delta V to reach a 33 degree Geosynchronous Earth Orbit [GEO, or 35,787 km (22,237 miles)], it does not have enough to reach an equatorial (0 degree) GEO. This will be accomplished by another vehicle to be described in a later diary. Stay tuned!

The OTV will have the following specifications:
  • Dimensions of 4.27 m (14.01 ft) in diameter and 10.80 m (35.42 ft) in length
  • Empty weight of 2,525 kg (5,611 lbs)
  • Uses an RL10B-2 Rocket Engine with an extendable nozzle
  • Uses 2,635 kg (5,810 lbs) of LH2 fuel
  • Uses 15,417 kg (33,989 lbs) of LO2 oxidizer
  • Uses Gaseous Hydrogen (GH2) and Gaseous Oxygen (GO2) for propellant tank pressurization
  • Uses a Fuel Cell for electrical power
  • Carries either a CM or up to 14,742 kg (32,500 lbs) of cargo
The OTV is simply an LH2 tank, LO2 tank, and RL10B-2 rocket engine all put together. It is carried aboard the Skylon intact, then fueled in orbit (to be described in a later diary).

The RCS quads operate the same way that the OUV quads do; they are stowed for the flight into space, then emerge when in space; only these quads use cryogenic fuel instead of hypergolic fuel.

The rocket engine nozzle will be retracted so that it can fit in the Skylon payload bay. The nozzle is extended when it reaches its destination in space. The nozzle can be retracted again if it ever needs to be returned back to earth.

 

The OTV is flown in the same manner as the OUV; which is to say, remotely.

 

The OTV can also have a CM attached to carry personnel, and a CM/PRM/OWT combination to do maintenance/repair, just like the OUV. The OTV is flown remotely by the pilot aboard the CM, and the PRM operators use the PRM remotely from inside the CM.

 

Various missions can now be designed around this vehicle.

OTV Missions:
  • Skylon Cargo Fetch. An OTV with an PRM can be used to move cargo back and forth between the Skylon to the LEOS. The Skylon can only reach 195 km altitude with a full load of 14,742 kg. The LEOS is at 385 km. A standard Hohmann Transfer requires that delta V1 = 0.055 kps and delta V2 = 0.055 kps, for a total round-trip delta V budget of 0.220 kps.
  • High Orbital Altitude Satellite Placement. An OTV can place a 2,007 kg (4,425 lbs) GPS satellite into equatorial SSEO. A standard Hohmann Transfer requires that delta V1 = 2.016 kps and delta V2 = 1.406 kps, for a total round-trip delta V budget of 6.845 kps (note: a delta V of 0.430 kps was added to the delta V2 burn for the 33 degree plane change requirement).
  • Space Station Re-Boost. The LEOS is calculated to suffer an orbital decay rate of 4 km/month; in five months, it will have dropped down to 265 km. A fully fueled OTV can be attached to the LEOS (or LEOSS) and be used to re-boosted it back up to 385 km. A standard Hohmann Transfer requires that delta V1 = 0.006 kps and delta V2 = 0.006 kps, for a total delta V budget of 0.012 kps.
  • Satellite Placement/Maintenance/Repair. An OTV with a CM/PRM/OWT can reach higher orbiting satellites that are in need of repair and/or maintenance. The delta V budget requirements will, as a result, vary according to mission requirements.
There are certainly other missions that that can be used by this versatile vehicle. These missions will be developed when the our plan is implemented.

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GEO Transfer Vehicle (GTV)
The GTV is a larger version of the OTV. It will be used to haul satellite payloads to SSEO or GEO.

The LH2 Tank and the LO2 Tank/RL10 Engine are brought up by the Skylon separately, then assembled in earth orbit.  Once assembled, the payload is attached, and the rocket is fueled.

The GTV will have the following specifications:
  • Dimensions of 4.7 m by 12.93 m (15.4 ft by 42.4 ft) less engine
  • Empty weight of 4,513 kg (9,950 lbs)
  • Uses 7,401 kg (16,367 lbs) of LH2 fuel
  • Uses 43,431 kg (95,749 lbs) of LO2 oxidizer
  • Uses Gaseous H2 (GH2) and Gaseous O2 (GO2) for tank pressurization
  • Uses GH2 and GO2 for RCS
  • Uses GH2 and GO2 for the Fuel Cell used for electrical power
GH2 and GO2 are used for tank pressurization, RCS, and electrical power because it is easier to operate this way. The following is a summary of what a normal spacecraft uses for its propellant, pressurization, RCS, and electrical systems, compared to how we do it:

  

Since the OTV can lift payloads of up to 2,007 kg to SSEO, the GTV will be used to lift larger payloads to higher altitudes. GTV missions:
  • Maximum payload to an equatorial SSEO: 18,214 kg (40,155 lbs). A standard Hohmann Transfer and 33 degree plane-change requires that delta V1 = 2.016 kps, and delta V2 = 1.836 kps, for a total round-trip delta V budget of 6.845 kps.
  • Maximum payload to an equatorial GEO: 11,209 kg (24,712 lbs). A standard Hohmann Transfer and 33 degree plane-change requires that delta V1 = 2.402 kps, and delta V2 = 1.888 kps, for a total round-trip delta V budget of 7.720 kps.
With the use of this vehicle, we can take over the entire satellite launching business. An estimated launch rate of about one hundred (100) LEO satellites per year, and ten (10) GEO satellites per year is predicted over the next ten (10) years.

Perspective, Please
Every single piece of space hardware described in this diary can fit inside the confines of the Skylon payload bay. The Skylon will take it to 195 km, and an OTV can do the rest at getting it to 385 km.

Below is an image of the sizes of the various vehicles discussed today relative to a completed LEOS.


 

Our space vehicles are now complete. All that is needed is missions to fly and astronauts to fly them.

Oh, and propellant, of course.

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