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With a Hat Tip to Frank Sinatra.

By now we have a firm foot hold in Low Earth Orbit (LEO), and we have all the spacecraft needed for full and smooth operations. Just as important, we also have all the underlying support structure needed to refuel and recharge our ships. Space is now a busy bee hive of scientific and other activity.

So it's now time to turn our gaze even higher; to stretch our wings, and to fly to other worlds.

Of course, in order to get to other worlds, we must have other-worldly vehicles.

These vehicles should have the following specifications:

Lunar Transfer Vehicle (LTV)
  • Three (3) GTVs connected together
  • Fuel tanks interconnected

OTV Lander
  • Lunar Lander kit attached to standard OTV
  • Kit includes landing legs, structure, landing radar, etc.
With these space vehicles, along with all the underlying support structures that are (by now) already in place, we will be able to do things that other space companies can only think about dreaming of: landing on the Moon.

Low Earth Orbit (LEO) operations is fine if a limited space program is desired. Going to the Moon, however, is an entirely different and a much more difficult proposition.

Landing on the Moon is a skill that only NASA was able to successfully accomplish (so far). We will be duplicating their efforts with one very important addition: we will be reusing our spacecraft!

Continued below the fold...

The LTV will get us to the Moon. The OTV Lander will complete the journey.


Lunar Transfer Vehicle (LTV)
The LTV is basically the shuttle between the Moon and the Earth. It can transport either cargo or passengers, just like her sister ship the Skylon.

It is nothing more than three (3) Geosynchronous Earth Orbit Transfer Vehicles (GTV) tied together. The fuel tanks are also interconnected, so that if an engine-out situation were to ever occur, the remaining engines can burn longer.

To review, each GTV has the following specifications:

  • Dimensions of 4.27 m (14.01 ft) in diameter and 16.05 m (52.66 ft) in length
  • Empty weight of 4,513 kg (9,950 lbs)
  • Uses an RL10B-2 Rocket Engine with an extendable nozzle
  • Carries 7,423 kg (16,366 lbs) of LH2 fuel
  • Carries 43,431 kg (95,749 lbs) of LO2 oxidizer
  • Uses Fuel Cells for Electric Power
  • 0.75% Delta V Reserve
Once the three GTVs are bolted together, the LTV will carry 22,272 kg (49,102 lbs) of LH2, and 130,293 kg (287,248 lbs) of LO2, for a total of 153,181 kg (337,706 lbs) of propellant, which includes 615 kg (1,357 lbs) of propellant reserve.

The LTV will carry either a CM round trip or 14,742 kg (32,500 lbs) of cargo one way.

LTV missions will originate from the Moon, since we will be manufacturing rocket fuel from there (this topic will be discussed in a future diary). In addition, the LTV will be operating in a Lunar POLAR Orbit (LPO) environment as well as the 33 degree-inclined LEO regime.

The following 14-Burn flight profile has been discussed:

LPO to 33 Degree LEO:
Burn 01: 0.558 kps: Departure Orbit Insertion (DOI)
Burn 02: 0.219 kps: 57 Degree Orbital Plane Change (OPC)
Burn 03: 0.417 kps: Trans Earth Injection (TEI)
Burn 04: 0.005 kps: Midcourse Correction #1 (MCC1)
Burn 05: 0.005 kps: Midcourse Correction #2 (MCC2)
Burn 06: 0.005 kps: Midcourse Correction #3 (MCC3)
Burn 07: 3.186 kps: Earth Orbit Insertion (EOI)

33 Degree LEO to LPO:
Burn 08: 3.161 kps: Trans Lunar Injection (TLI)
Burn 09: 0.005 kps: Midcourse Correction #4 (MCC4)
Burn 10: 0.005 kps: Midcourse Correction #5 (MCC5)
Burn 11: 0.005 kps: Midcourse Correction #6 (MCC6)
Burn 12: 0.283 kps: Lunar Orbit Insertion (LOI)
Burn 13: 0.219 kps: 57 Degree Orbital Plane Change (OPC)
Burn 14: 0.558 kps: Lunar Orbit Circularization (LOC)

8.634 kps: Delta V Budget
0.065 kps: 0.75% Delta V Reserve
8.699 kps: Total Delta V Budget

The DOI and LOI burns place the LTV into an elliptical orbit, so that the OPC burn can occur at apoapsis, which is the point that the vehicle is traveling the slowest.

Transit Time
It will take less than 10 days to transport cargo one-way or a CM round-trip between the Moon and Earth.

0.5 Days: DOI to OPC
0.5 Days: OPC to TEI
3.0 Days: TEI to EOI
4.0 Days: Travel Time From Moon to Earth

4.5 Days: TLI to LOI
0.5 Days: LOI to OPC
0.5 Days: OPC to LOC
5.5 Days: Travel Time From Earth to Moon

Total round trip transit time is 9.5 days. This leaves 18 days until the Earth lines back up again for the trip back to Earth, since it takes 27.5 days for the Moon to make one circuit around the Earth. Thus, we have 18 days to refuel the spacecraft.

Flights can leave the Earth for the Moon at any time. Polar orbit alignment only occurs at the Moon, so there are no launch windows from Earth.

The LTV will be able to carry the following payloads:

Payload To Earth: 0 kg
Payload To Moon: 14,742 kg (Standard Skylon Payload)
Propellant: 152,566 kg

Payload To Earth: 29,484 kg (2X Standard Skylon Payload)
Payload To Moon: 0 kg
Propellant: 131,711 kg

Payload To Earth: 7,310 kg (Crew Module)
Payload To Moon: 7,310 kg (Crew Module)
Propellant: 129,796 kg

The LTV will fly to Earth empty and pick up a load at the LEOS. The LTV then returns back to the Moon carrying its cargo.

Since it takes time to chase down and rendezvous with the LEOS, the CM will be set for a ten (10) day duration. The CM will be be exchanged for a recharged CM while at the LEOS. When the LTV returns to the Moon, the CM is placed in Quiescent Mode for the 18 day refueling period. The CM is then reactivated when the Earth-bound crew arrives.

Once lunar orbital refueling becomes routine (the subject of a future diary), then the LTV can be put on routine schedule.

OTV Lander
To reach the Moon, and not land on it, would almost seem a waste. While there are certainly many scientific things that can be accomplished in lunar orbit, imagine what we can do on the lunar surface!

In keeping with our theme of reuse and commonality, an Orbital Transfer Vehicle (OTV) will be outfitted with a lunar lander kit that will transform the OTV into a upright lunar lander.

Once the kit is bolted on and the radar turned on, it is ready for lunar operations.

The OTV lander can carry a standard Skylon payload. The payload is carried aboard the OTV lander in the same way that payload is loaded into the Skylon.

The CM is installed a little differently. Since it should sit upright, there is a second spike coming out of the bottom of the CM. This is inserted into the holder on the OTV Lander, in the same way normal payload is loaded.

Once on the lunar surface, the astronauts use the airlock to climb out onto the porch. From there, they make the long and (admittedly) arduous decent down to the lunar surface, and into history.

Since fuel will be made on the lunar surface, most, but not all, flight profiles will use the Moon as the point of departure.

The following flight profiles have been discussed:

Lunar Surface to LPO:
Burn 01: 1.853 kps: Ascent Phase Initiation (API)
Burn 02: 0.017 kps: Terminal Phase Initiation (TPI)

LPO to Lunar Surface
Burn 03: 0.063 kps: Descent Phase Initiation (DPI)
Burn 04: 2.065 kps: Powered Descent Initiation (PDI)

3.998 kps: Delta V Budget
0.030 kps: 0.75% Delta V Reserve
4.028 kps: Total Delta V Budget

The OTV Lander will be able to carry the following payloads:
Takeoff then Land
Payload To LPO: 0 kg
Payload To Lunar Surface: 14,742 kg (Standard Skylon Payload)
Propellant: 17,838 kg

Payload To LPO: 7,310 kg (CM)
Payload To Lunar Surface: 7,310 kg (CM)
Propellant: 14,841 kg

Land then Takeoff
Payload To Lunar Surface: 0 kg
Payload To LPO: 14,742 kg (Standard Skylon Payload)
Propellant: 16,530 kg

Payload To Lunar Surface: 7,310 kg (CM)
Payload To LPO: 7,310 kg (CM)
Propellant: 14,841 kg

Missions originating from LPO will have basically the same Delta Vs, and so will have basically the same payload parameters.

Because the OTV Lander winds up in LPO, it can theoretically land at any point on the lunar surface. This is one of the may advantages of operating from polar orbit as opposed to an equatorial orbit.

The Portrait
We can see what each vehicle looks like compared to the LEOS. The OTV Lander will be bolted together at the LEOS, then transfered to LPO for lunar operations.

We now have an even busier bee hive of activity.

In Closing
Our journey is almost complete. We have the means to get to LEO, and we now have the means to go a place where only NASA dared to tread.

Because we have reused space hardware, we can fly to the Moon a little more economically than NASA ever dreamed of.

Landing on the Moon is not enough; we also need a place to stay for a while so that we could (responsibly) exploit our surroundings.

Of course, that's a story for another day.


A version of this article is cross posted at NMSTARG

With the humblest of apologies for any confusion, this technical paper is a fluid and dynamic process, and so the diary series has changed (again) accordingly. As you can see, it is now out of order. The GTV should have been described under the Space Ships heading. I could have then described the refueling operations next, and then talked about the Lunar Ships. We decided that the series makes more sence this way. Mostly, it reflects the changes made to the NMSTARG website. The DKos diary series so far:

  1. Overview
  2. History, Part I
  3. History, Part II
  4. Proposal
  5. Space Port
  6. Space Plane
  7. Space Stations
  8. Space Ships
  9. Recharge and Resupply
  10. Lunar Ships
  11. Lunar Bases
  12. Lunar Propellant
  13. Startup
  14. Revenue
  15. Advanced Systems
FULL DISCLOSURE: I work for the New Mexico Space Technology Applications Research Group (NMSTARG), a commercial space flight venture, which in its current form exists as an unfinished technical paper. NMSTARG is not affiliated with any of the businesses that were discussed in these posting. These diaries exists as a way for the DKos community to get a first look at our research, and to ask said community for any technical and non-technical (just as important!) feedback. The paper provides information on how to make a profit in space, detailing the infrastructure that will be needed and all of the associated costs involved. As such, we hope that it eventually attracts the attention of investors, where the paper then becomes the technical portion of a space-related business plan.

Originally posted to The NM STAR Group on Sun Nov 04, 2012 at 09:00 AM PST.

Also republished by Astro Kos.

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