An Orbital Gas Station

Our last entry looked at the various spacecraft designs needed for the widely varying missions that our space endeavors call for.

However, the final piece missing from our jigsaw puzzle reveals itself: what happens when you need a pit-stop? The answer, just like in all of astronautics, is to bring it with you.

We will be discussing the various ways to quickly and easily replenish consumables used by our spaceships. Time and ease of operations are more important than any other factor (except safety, of course), so some things may be done in a different, less efficient manner.

Our gas station needs to have the following specifications:

OUV Resupply Module (ORM)

• Dimensions of a standard Habitation Module
• Hypergolic propellant refill
• Battery recharge

CM Resupply Module (CRM)

• Dimensions of a standard Habitation Module
• Atmospheric gases refill
• Battery recharge

Propellant Pressurization Module (PPM)

• Dimensions of a standard Habitation Module
• Cryogenic propellant refill

With these modules lifted into orbit and plugged into a Solar Power Station, we can replenish consumables in orbit, while simultaneously taking one step closer to declaring ourselves a true space-faring civilization.

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All vehicles run on some kind of propellant; alas, all vehicles therefore need to have their propellant restocked, otherwise the vehicle is useless. The analogy can be extended to a pistol: it is useless as a projectile-firing device if you can't replenish the projectiles.

Orbital Vehicle Resupply

Consumable resupply modules will be using standard habitat modules as its base. There will be two (2) different types of resupply Modules. Each module will have the following characteristics in common:

• Dimensions of 4.7 m by 11.0 m (15.4 ft by 36.1 ft)
• Weight of no more than 14,742 kg (32,500 lbs)
• Refurbished for reuse on earth, then brought up on a Skylon

The modules use a Solar Power Station for electrical power. This creates an Orbital Resupply Station (ORS). There will be two (2) types of ORS: the OUV ORS and the CM ORS.

OUV ORS

The OUV ORS replenishes the OUV, as the name implies. Each has the following specifications:

• LHe resupply (1 kW)
• UDMH resupply (1 kW)
• MON25 resupply (1 kW)
• Battery Recharger (4 kW)
• Total power requirement: 7 kW
• Total number of recharges: Four (4)

Three OUVs can dock at the OUV ORS, thus three OUVs can be replenished at the same time. That means that a total of twelve (12) OUVs can be recharged.

CM ORS

The CM ORS replenishes the CM, also as the name implies. Each module has the following specifications:

• LHe resupply (1 kW)
• LN2 resupply (1 kW)
• LO2 resupply (1 kW)
• H2O resupply (1 kW)
• Battery Recharger (4 kW)
• Total power requirement: 8 kW
• Total number of recharges: Six (6)

Liquid Nitrogen (LN2) and Liquid Oxygen (LO2) are used for the CM atmosphere, and the water is used for drinking, toilet, etc. Two CMs can dock at the CM ORS, thus two CMs can be replenished at the same time. That means that a total of twelve (12) CMs can be recharged.

The OUVs and CMs can now go about its various jobs, safe in the knowledge that a service station is just down the street, so to speak.

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Orbital Propellant Resupply

The OUV ORM and the CM ORM described above gives us the experience needed to perform cryogenic tank refilling operations, since LHe, LN2, and LO2 are all at cryogenic temperatures.

It is now time to go on to bigger and better things.

A Propellant Pressurization Module (PPM) supplies the pressurization needed to compel propellant from the refueling tank into the vehicle tank. The battery supplies the electrical power needed to operate the PPM.

Each refueling tank weighs 265 kg (584 lbs), and has a standard Docking port on one end. A Skylon Propellant Replenishment System is attached to the other end, similar to the system used to refill the Skylon spacecraft on the Spaceport Fuel Apron. This should help to vastly simplify refueling operations.

An OUV attaches to the docking port of the PPM and maneuvers it to a refueling tank, where it attaches to that as well. The entire contraption is then docked with the GTV, where the PPM supplies the necessary pressurization needed to refill the GTV tanks.

Each of the PPMs will have the following specifications:

• Dimensions of 4.7 m by 11.0 m (15.4 ft by 36.1 ft)
• Weight of no more than 14,742 kg (32,500 lbs)
• Refurbished for reuse on earth, then brought up on a Skylon
• LH2 resupply
• LO2 resupply
• Total number of recharges: Three (3)

This means that the number of LH2 recharges is less than three (3) and the number of LO2 recharges is nine (9).

The GTV now have the freedom to stretch its boundaries and to go to places previous unreachable even by NASA.

Our city in space is now fully functional, complete with suburbs and now a gas station!

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In Closing

Because the folks at Reaction Engines, Ltd worked out an automated process for replenishing their Skylons with cryogenic fuel, we can use the same technology to refill our spacecraft. This is in keeping with our philosophy of reuse and commonality. This should help to lower design and production costs as well.

As the capability of orbital refueling becomes routine, we will truly begin to reach for the stars.

But we'll reach for the moon first. Of course, that's a story for another day.

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