A New Earth-Moon Transportation System

LTS is developing a new lunar architecture that has a number of advantages over current known and evolving architectures. Our architecture uses new innovations for modularity and flexibility, leading to reduced development cost, a faster development schedule, and better evolvability.

LTS architecture will enable NASA to meet its near-term strategic objectives including: sending small payloads to the lunar surface in a few short years, sending larger payloads to the lunar surface in succeeding years, and sending crews to the Moon and back to the Earth by the middle of the next decade.

LTS is a privately financed company that requires encouragement and cooperation from NASA to raise the private capital required to design, build, ground test, flight test, and operate its Earth-Moon transportation system.

About Lunar Transportation Systems, Inc.

Our Mission

To create the equivalent of a two-way highway between the Earth and the Moon with refueling stations along the way.

Our Plan

To utilitze existing ELVs and a small fleet of new, reusable spacecraft that are refueled in cislunar space.

Our Goal

To develop a rapidly deployable Earth-Moon transportation system.

Our Methodology

To develop a fleet of LTS spacecraft that are sized to fit the payload envelope and the payload capabilities of Delta II class launch vehicles to validate LTS concepts and to deliver small payloads to and from the lunar surface. Once LTS concepts are validated using Delta II Heavy class launch vehicles in a series of flight demonstration missions, develop a fleet of larger spacecraft that are sized to fit the payload envelope and payload capabilities of Delta IV Heavy class launch vehicles. These larger LTS spacecraft will be capable of bringing crews and heavy payloads to and from the lunar surface.

Lunar Transportation Systems encompasses two separate but related companies. The first company, Lunar Transportation Systems, Inc., is an intellectual property company.

Lunar Transportation Systems, Inc. Roles and Responsibilities

Lunar Transportation Corporation, Inc. Roles and Responsibilities

LTS System Summary

Brief LTS Earth-Moon Transportation System Description

This system builds the equivalent of a two-way highway between Low Earth Orbit and the lunar surface. The system uses a small fleet of reusable spacecraft, supported by a small fleet of expendable spacecraft, to transfer payloads in LEO, to transfer cryogenic propellant tanks at relatively stable locations in cislunar space, and to transport payloads to and from the lunar surface. The system uses existing ELVs to transport all of its infrastructure from the Earth to Low Earth Orbit.

A New Lunar Architecture

Most of the concepts for lunar transportation architecture that are being considered today by NASA and the aerospace industry are based on decades of study of early spaceflight concepts. In our view these architectures are not an acceptable solution for a new lunar transportation system that will be required to support emerging lunar activities at reasonable cost. Genuine innovation is needed to achieve the goals of affordability and sustainability called for by the President.

LTS is developing a new lunar architecture concept that, we believe, is better suited for a state-of-the-art lunar transportation system. This architecture is characterized by modularity and extreme flexibility leading to reduced development cost and better evolvability. A hard look at this architecture will show that it enables NASA to meet its strategic objectives, including sending small payloads to the lunar surface in a few short years, sending larger payloads to the lunar surface in succeeding years, and sending crews to the Moon and back to the Earth by the middle of the next decade.

Use of Existing ELVs

This new lunar architecture utilizes current ELVs to bring a new fleet of reusable spacecraft, lunar payloads, propellants, and eventually crews from the Earth to LEO. The reusable LTS spacecraft do the rest of the job. They take payloads from LEO to the Lunar surface and bring payloads back to Earth from the Moon. This architecture permits a “pay as you go” and a “technology development pathway” that allows NASA to achieve a series of its strategic objectives as funding and technology developments permit. The LTS approach reduces mission recurring cost by advancing in-space transportation technology, and later, lunar resource utilization, because this is much less costly than investing in new Earth to Orbit (ETO) transportation.

Lunar Payload Capabilities

The size of the payloads delivered to and from the Moon depends on where and how many times Lunar Landers are refueled on their way to and from the lunar surface. The initial fleet of reusable spacecraft are sized to fit the payload capabilities of Delta II Heavy class launch vehicles. This architecture is capable of delivering 800 kg to the lunar surface directly from LEO without the need to refuel in space. It is capable of delivering payloads of 3 metric tons to the Lunar surface with refueling at L1 only. And it is capable of delivering 6 metric tons to the lunar surface with refueling at MEO, at L1, and in lunar orbit. Comparable payloads can be returned from the lunar surface to LEO or to the Earth by refueling the Lunar Lander at one or more of those locations. While this initial system is not meant to transport crews to and from the Moon, it is meant as a technology development testbed for a crewed Earth- Moon transportation system.

Reusability

A key feature of this Earth-Moon transportation system is that the two principal LTS spacecraft, the Lunar Lander and the Propellant Transporter, are reusable. The Lunar Lander transports payloads from LEO to the Lunar surface and back. The Propellant Transporter transports cryogenic propellant tanks from LEO to any place in cislunar space where Lunar Landers need to be refueled.

Enabling Technologies

This state-of-the-art architecture does not depend on the development of any new heavy-lift launch vehicles. It does depend on the development of six emerging technologies: 1) an autonomous rendezvous and docking system, 2) an autonomous payload transfer system, 3) a spacecraft-to-spacecraft cryogenic propellant tank transfer system, 4) an autonomous propellant tank tapping system, 5) an autonomous lunar landing system, and 6) an autonomous lunar payload offload system. Developing these technologies is less risky and less costly than investments in new ETO transportation or cryogenic propellant transfer technologies. These emerging technologies, except AR&D;, can be developed by ground test. The LTS program plan includes a flight demonstration program in LEO and early robotic missions to the Moon to validate these technologies.

Scalability

This new lunar transportation system is scalable. A follow-on fleet of larger spacecraft, designed to fit the payload capabilities of Delta IV Heavy class launch vehicles, can transport payloads of up to 30 metric tons from LEO to the lunar surface, depending on where and how frequently they are refueled on their way to and from the Moon. These larger spacecraft will be capable of transporting crews to the lunar surface and returning them to the Earth. They will also have the capability to provide heavy cargo transportation to support a permanent lunar base.

Methodology

LTS plans to develop a fleet of spacecraft that are sized to fit the payload envelope and the payload capabilities of Delta II Heavy launch vehicles to validate LTS concepts and to deliver payloads to and from the lunar surface. Once LTS concepts are validated using Delta II Heavy launch vehicles in a series of flight demonstration missions, LTS plans to develop larger spacecraft that are sized to fit the payload envelope and payload capabilities of Delta IV Heavy class launch vehicles. The larger spacecraft fleet will have the capability to bring crews and heavy payloads to and from the Moon.

Crew Safety

A very important element of the LTS lunar architecture is crew safety. Commonality of modules and subsystems increases flight operations experience rapidly, leading to greater safety. Backup Lunar Landers can be prepositioned at L1, in lunar orbit, or even on the lunar surface to provide crew rescue capability in case of a mission abort situation.

Cost Reduction

The nonrecurring costs to develop this Earth-Moon transportation system are much lower than the cost of developing systems that use more traditional architectures because there are fewer unique developments and it relies on existing launch vehicles. A significant reduction in lunar mission costs comes from the reusability of the major elements of the LTS system.

The largest cost – perhaps as much as 70% of each lunar mission – is the delivery of the spacecraft, the propellants, and the lunar payloads from the Earth to LEO. LTS will complete this phase using existing expendable launch vehicles. While these are expensive to fly, the development cost of significant new launch capability represents dozens of launches and many years of flight operations experience. When propellants can be manufactured
on the Moon, Earth-Moon mission costs may be reduced by 60% or more. If and when reusable Earth-to-LEO launch vehicles become available, lunar mission costs may be reduced by a further 60% or more.

Schedule

Because this system relies on existing technologies and existing ELVs and requires only the maturation of several enabling technologies, it can deliver payloads to the lunar surface relatively quickly and well within NASA’s schedule for robotic and human lunar exploration.

The Bottom Line

The LTS lunar architecture is based on concepts that reduce lunar mission life-cycle costs and technical risks, improve reliability and crew safety, accelerate lunar mission schedules, and allow for the routine delivery of lunar payloads on the equivalent of a two-way highway between the Earth and the Moon.

Capabilities

The size of the payloads delivered to and from the Moon depends on where and how many times Lunar Landers are refueled on their way to and from the lunar surface. The LTS system is capable of delivering 800 kg to the lunar surface directly from LEO without the need to refuel in space. It is capable of delivering 3 metric tons to the lunar surface with refueling at L1 only. And it is capable of delivering up to 6 metric tons to the lunar surface with refueling at MEO, at L1, and in lunar orbit. Comparable payloads can be returned from the lunar surface to LEO or to the Earth with refueling at one or more of those locations.

The LTS system can also be used as a testbed for the development of Constellation Systems technologies in LEO, at L1, in lunar orbit, on the lunar surface, and on Earth return and reentry missions from the Moon.

Lunar Payloads

The LTS system, scaled to be launched with Delta II Heavy launch vehicles, is capable of delivering up to 6 metric tons to the lunar surface.
The following chart shows three Lunar mission profiles: the LEO to lunar surface direct mission is capable of delivering 800 kg to the lunar surface; refueling at L1 increases the capability to 3 metric tons; and refueling at MEO, L1, and in Lunar orbit increases the capability to 6 metric tons.

Constellation Systems Testbed

The LTS system can be used to test NASA Constellation Systems technologies in LEO, in cislunar space, in lunar orbit, on the surface of the Moon, and on return missions to the Earth.

The LTS system can be used to develop Constellation Systems technologies in LEO, in translunar space, in lunar orbit, on the Lunar surface, and on missions returning from the Moon. These technologies include autonomous rendezvous and docking, on-orbit vehicle and spacecraft assembly, checkout, launch, mission operations, autonomous propellant transfer, autonomous robotic systems, Lunar Orbit Rendezvous systems, lunar landing systems, and payload offload systems. The LTS system can be used to flight-test components of Constellation systems in LEO, in translunar space, in lunar orbit, on the lunar surface, and Earth reentry systems returning from the Moon. The LTS system can also be used to develop and test lunar mission operational procedures.

Spacecraft

LTS system architecture is built around a fleet of two different reusable spacecraft and a fleet of two expendable spacecraft. The reusable spacecraft, which make up the heart of the system, are the Lunar Landers and the Propellant Transporters. These two types of reusable spacecraft perform different functions in the system.

The Payload Dispenser, the Propellant Dispenser, and the Propellant Transporter, operate only in space. The Lunar Lander operates in space as well as on the lunar surface.

The structures of the Lunar Lander and the Propellant Transporter are nearly identical and consist of an inner aluminum tube that carries three aluminum plates, one at each end of the tube and one middle plate located below the mid section of the spacecraft. Six sets of cryogenic propellant tanks, arranged in a circle, fit between the plates. These tank sets are so attached that they can be robotically transferred from one spacecraft to another. Each tank set consists of a tall hydrogen tank and a shorter oxygen tank, with the six hydrogen tanks located on top of the central plate and the six oxygen tanks located on top of the bottom plate.

The Lunar Lander

The reusable Lunar Lander is used to carry payloads from LEO to the lunar surface and return payloads from the Moon to the Earth.
Lunar Landers are brought from Earth to LEO on ELVs. Their purpose is to deliver payloads from LEO to the lunar surface and to return payloads from the lunar surface to LEO or directly to the Earth. Lunar Lander spacecraft receive payloads from Payload Dispenser spacecraft in LEO, receive propellant tank sets from Propellant Dispensers in LEO, and may receive propellant tank sets from Propellant Transporters wherever they require refueling in cislunar space. Lunar Landers may be refueled by Propellant Transporters in MEO, at L1, and/or in lunar orbit, depending on the size of the payloads they are transporting to the lunar surface. Lunar Landers have a single hydrogen/oxygen rocket engine, ACS thrusters, a fuel cell power source, computers, an inertial guidance system, and an autonomous rendezvous and docking system.

Using their autonomous rendezvous and docking system, Lunar Landers robotically receive propellant tank sets from either Propellant Dispensers or Propellant Transporters. They also contain mechanisms to autonomously tap into their propellant tanks to create propellant flow to their rocket engine.

A set of retractable landing legs folded back along the structure allows Lunar Lander spacecraft to land on the Moon and take off from the Moon. Lunar Landers are reusable and provide reliable two-way transportation between Earth orbit and the lunar surface.

The Propellant Transporter

The Propellant Transporter is used to transfer propellant tank sets to the Lunar Lander anywhere it requires refueling in cislunar space.
Propellant Transporters are brought from the Earth to LEO on ELV’s. Propellant Transporters bring propellant tank sets beyond Earth orbit to any location where Lunar Landers require refueling in cislunar space. They can travel to MEO, L1, and/or lunar orbit to provide refueling stations for the Lunar Landers.

Propellant Transporters are nearly identical to Lunar Landers but have no landing legs since they are not designed to land on the Moon. Propellant Transporters have a single rocket engine, ACS thrusters, a fuel cell power source, computers, an inertial guidance system, and an autonomous rendezvous and docking system. Propellant Transporters are reusable and form the backbone of this Earth-Moon transportation system.

The Payload Dispenser

The Payload Dispenser is used to transfer payloads to the Lunar Lander after it has been launched to LEO on an ELV.
Payload Dispensers bring payloads to LEO on ELVs. They provide a common interface with the Lunar Landers, rendezvous and dock with Lunar Landers, and transfer their payloads to Lunar Landers in LEO for transport to the lunar surface. Payload Dispensers are then discarded and enter the Earth’s atmosphere after a single use.

Payload Dispensers do not have a rocket engine. They contain an AR&D; system for rendezvous and docking, an Orbital Maneuvering System (OMS) to reach their designated locations in LEO for rendezvous with a Lunar Lander, and an Attitude Control System (ACS) to achieve proper attitude for docking.

The Propellant Dispenser

The Propellant Dispenser is used to transfer propellant tank sets to either a Lunar Lander or a Propellant Transporter after it has been launched to LEO on an ELV.
Propellant Dispensers bring propellant tank sets to LEO on ELVs. Once in Earth orbit, Propellant Dispensers rendezvous and dock with either Lunar Landers or Propellant Transporters and transfer cryogenic propellant tank sets to their receiving spacecraft. Propellant Dispensers are simple, relatively inexpensive spacecraft that are discarded after a single use.

Propellant Dispensers do not have a rocket engine nor are they able to tap into the propellant tanks they carry. Propellant Dispensers contain an autonomous rendezvous and docking system, an Orbital Maneuvering System (OMS) to reach their proper designated locations in LEO for rendezvous and docking with a receiving spacecraft, and an Attitude Control System (ACS) to achieve proper attitude for docking and separation. Propellant Dispensers have the capacity to carry up to six propellant tank sets.

The Rocket Engine

A single small LOX/Hydrogen rocket engine is used by the Lunar Lander and the Propellant Transporter.
The Lunar Lander and the Propellant Transporter are the two LTS spacecraft that are rocket powered. The specific impulse of the engine has a significant affect on the performance of the system and a value of 440 sec. has been assumed in our computations. An engine that meets those requirements is a version of the Pratt & Whitney RL-10. To fit the size limitations of the fairing of the Delta II Heavy rocket, the rocket engine may have to be modified to fit into the 0.9-meter space available in LTS spacecraft. Throttlability: To compensate for rocket shutdown transience, a small amount of thrust modulation will be required.

Expendable Launch Vehicles (ELVs)

One of the requirements of this Earth-Moon transportation system was to size all LTS spacecraft for the payload envelope and the payload capability of existing expendable and possible future reusable launch vehicles.

Initially, Delta II Heavy ELVs will be used to validate LTS concepts in LEO, in MEO, at L1, in lunar orbit, on the lunar surface, and on return flights from the Moon to the Earth. Later, once the LTS concepts have been validated, the LTS fleet of spacecraft can be scaled up to fit the payload envelope and the payload capabilities of Delta IV Heavy class EELVs which will be able to bring as much as 30 metric tons to the lunar surface. A scaled-up version of the LTS system will be capable of sending crews to and from the Moon and can provide large cargo payloads to support a permanent lunar base.

There are several reusable and partially reusable launch vehicles currently under development and if and when these become operational, it is the intent of LTS to use these new capabilities to dramatically reduce lunar mission costs. Kistler Aerospace Corporation has already completed a study for LTS on the use of their K-1 vehicles to launch and deploy LTS spacecraft, propellant tanks, and lunar payloads to LEO.

Delta II Heavy Launch Vehicle

The Delta II Heavy ELV is the baseline launch vehicle to launch all LTS spacecraft, propellants, and payloads from the Earth to LEO.
The Delta II Heavy was chosen because of its long history of reliability and its capacity to carry 6 metric tons of payload to LEO. All LTS spacecraft are sized to fit the payload envelope of Delta II Heavy ELVs.

Delta IV Heavy Launch Vehicle

The Delta IV Heavy ELV is the baseline launch vehicle to launch all elements of a scaled up version of the LTS system.
LTS spacecraft can be scaled-up and sized to fit into the payload envelope and the payload capabilities of the Delta IV Heavy evolved expendable launch vehicle. These scaled up LTS spacecraft can be used to carry elements of Crew Exploration Vehicles as well as much larger payloads to and from the Moon.

Reusable Launch Vehicles

LTS intends to employ reusable launch vehicles if and when these capabilities become available.
LTS is aware that several reusable and partially reusable Earth to LEO launch vehicles are currently under development and plans to employ these much lower cost launch vehicle systems if and when they become available.

Architecture

The LTS architecture can accommodate a wide range of mission profiles, including LEO to lunar surface direct; LEO to L1 to lunar surface; LEO to MEO to L1 to lunar orbit to lunar surface, with refueling at one or more locations along the way. There is also a wide range of profiles for Earth return missions using the LTS architecture. Selected mission profiles depend on the size of the payloads required for specific types of lunar missions.

Mission Profile 1 - LEO to Lunar Surface Direct

A mission from LEO direct to the Moon is capable of delivering 800 kg to the lunar surface.
Earth to LEO to Lunar Surface Direct
This mission profile requires no refueling in space.

  1. An LTS Lunar Lander is launched to LEO on an ELV.
  2. A Payload Dispenser is launched to LEO on an ELV.
  3. The Lunar Lander rendezvouses and docks with the Payload Dispenser in LEO.
  4. The Payload Dispenser transfers its payload to the Lunar Lander in LEO.
  5. The Payload Dispenser separates from the Lunar Lander and deorbits into the Earth’s atmosphere.
  6. The Lunar Lander departs LEO for the lunar surface.
  7. The Lunar Lander lands on the Moon.
  8. The Lunar Lander offloads its payload onto the lunar surface.

Mission Profile 2 - LEO to L1 to Lunar Surface

The Lunar Lander is refueled by the Propellant Transporter at L1 and then travels to the lunar surface with a payload of up to 3 metric tons.
Earth to LEO to L1 to Lunar Surface
This mission profile allows 3 metric tons to be transported from the Earth to the lunar surface. It requires a Propellant Transporter to refuel the Lunar Lander at L1.

  1. A Lunar Lander is launched to LEO on an ELV.
  2. A Payload Dispenser is launched to LEO on a second ELV.
  3. The Lunar Lander rendezvouses and docks with the Payload Dispenser in LEO.
  4. The Payload Dispenser transfers its payload to the Lunar Lander in LEO.
  5. The Payload Dispenser separates from the Lunar Lander and deorbits into the Earth’s atmosphere.
  6. The Lunar Lander departs LEO for L1.
  7. A Propellant Transporter is launched to LEO on a third ELV.
  8. The Propellant Transporter departs LEO for L1.
  9. The Lunar Lander arrives at L1 and ejects its spent propellant tanks.
  10. The Propellant Transporter rendezvouses and docks with the Lunar Lander at L1.
  11. The Propellant Transporter transfers its propellant tank sets to the Lunar Lander.
  12. The Propellant Transporter separates from the Lunar Lander at L1.
  13. The Lunar Lander departs L1 for the Moon.
  14. The Lunar Lander lands on the Moon.
  15. The Lunar Lander offloads its payload onto the lunar surface.

Other Mission Profiles

The LTS architecture is very flexible. Larger payloads, up to 6 metric tons, can be delivered from LEO to the lunar surface with refueling at MEO, L1, and/or Lunar orbit.
Other Lunar mission profiles are possible using the LTS propellant tank transfer system, that can refuel Lunar Landers at relatively stable locations in cislunar space. A mission profile that includes refueling at MEO, L1, and lunar orbit, for example, is capable of landing payloads of up to 6 metric tons onto the lunar surface.

Returning Payloads from the Moon

The LTS architecture allows a wide range of payloads to be returned from the Moon. The size of the payloads depends on where and how many times the Lunar Landers are refueled on their return to Earth.
The LTS system is capable of returning payloads from the Lunar surface to LEO or to the Earth. The size of payloads returning from the Moon depends on how many times and at which cislunar locations the returning spacecraft is refueled on its way from the Moon to the Earth.

Emerging Technologies

The LTS transportation system is made possible by the development of a small fleet of reusable spacecraft that can transport cryogenic propellants to any relatively stable location in cislunar space to refuel Lunar Landers on their way to and from the Moon. The LTS system does not require the development of new heavy-lift boosters but does require the use of six emerging technologies.

Autonomous Rendezvous and Docking

The LTS system uses an autonomous rendezvous and docking system to transfer payloads and cryogenic propellant tanks.

All LTS spacecraft use an autonomous rendezvous and docking system, several of which are currently in development. Autonomous rendezvous and docking will be required to transfer lunar payloads from Payload Dispensers to Lunar Landers in LEO, to transfer cryogenic propellant tanks from Propellant Transporters to Lunar Landers in MEO, at L1, and in lunar orbit, and to replenish propellant tanks from Propellent Dispensers to Propellant Transporters and Lunar Landers in LEO.

A good example of a current automatic rendezvous and docking system is the new EADS Sodern Videometer, that is being developed for the ESA Automated Transfer Vehicle (ATV). This new-technology device ensures very precise automatic rendezvous and docking operations. Based on the design of a star tracker, the videometer is the first automatic optical system ever used for spacecraft navigation. For the final rendezvous maneuvers, the spacecraft use their videometer sensors, combined with additional parallel measurement systems, which allow automatic docking with centimeter precision.

The videometer system is able to analyze images of its emitted laser beam automatically reflected by passive retro reflectors serving as targets installed on receiving LTS spacecraft. During the last 200 meters of the final approach maneuver, the videometer automatically recognizes the retro reflector target patterns and then calculates the distance and direction to the docking port. This precise tracking of the relative motion between the two spacecraft as they get closer provides information to the on-board Guidance, Navigation and Control (GNC) system, which automatically pilots the two spacecraft together.

An LTS spacecraft docking system is currently in conceptual design.

Autonomous Payload Transfer

The LTS system uses an autonomous payload transfer system to transfer lunar payloads from Payload Dispensers to Lunar Landers in LEO.
Lunar-bound payloads are integrated on top of special LTS Payload Carriers that are installed on the top plates of Payload Dispensers. These Payload Carriers are robotically transferred to Lunar Landers in LEO prior to the Lunar Lander’s departure to the Moon. After the two spacecraft have been brought in very close proximity (within a couple of centimeters of proper position and attitude with respect to each other), the lead spacecraft will order a last gentle push from the thrust control jets to bring the two spacecraft into full contact. Tapered pins protruding from the top plate of one vehicle will engage tapered holes in the top plate of the second spacecraft. Electromagnets will then be energized in order to keep the two spacecraft solidly locked together. The top plates in the two spacecraft carry diametrical recessed grooves containing geared pinions. A Payload Carrier, which carries a similar plate with a dented rail fitting inside the recessed groove, is held solidly by the rims of the groove and is prevented from sliding along the groove by the geared pinion.

The Payload Carrier
After the two spacecraft are docked and connected, the payload transfer is initiated. An electric motor actuates the geared pinion of the transferring spacecraft, which slowly moves the payload along the grooves of the first spacecraft so it engages the groove in the receiving spacecraft. At this point the geared pinion of the receiving spacecraft takes control and moves the payload to its exact position in the middle of its top plate and keeps it solidly in this position by locking the driving mechanism. The electric magnets are then released and the Payload Dispenser separates from the Lunar Lander and reenters the Earths atmosphere. The Lunar Lander then proceeds to the Moon.

Autonomous Propellant Tank Transfer

The LTS system uses an autonomous propellant tank transfer system capable of transferring propellant tanks in LEO and in cislunar space.

Refueling in Space

The heart of this lunar transportation system is the use of prefilled, self-contained, cryogenic propellant tank sets. These tank sets are transported from the Earth to Low Earth Orbit on ELVs in LTS Propellant Dispenser and Propellant Transporter spacecraft. Propellant Dispenser spacecraft transfer their propellant tank sets to returning Propellant Transporters in LEO so they can be reused. Fully fueled Propellant Transporter spacecraft can travel to MEO, L1, and/or lunar orbit where they are positioned to transfer their full propellant tank sets to Lunar Landers both on their way to the Moon and, if required, on returning flights from the Moon.

Both Lunar Lander and Propellant Transporter spacecraft are guided to pre-defined locations using their Orbital Maneuvering Systems for rendezvous and docking. The attitudes of the spacecraft will be aligned using their inertial guidance systems and their attitude control systems. After a Lunar Lander spacecraft has moved to its intended location, it uses its autonomous rendezvous and docking system to achieve proper attitude and position near a Propellant Transporter spacecraft. Once the two spacecraft are docked, magnetic clutches temporarily lock them together. At that point, a telescoping arm with a gripper extends from the central tube of the Propellant Transporter toward the Lunar Lander, grabs the waistband of the facing tank in the donor vehicle, pulls the tank to its assigned position in the receiving spacecraft, and solidly holds it in place. The angles of rotation around the longitudinal axis are controlled so that the empty tank berth in the receiving spacecraft faces the occupied berth of the donating spacecraft.

The same transferring action proceeds simultaneously with the upper row of hydrogen tanks. A telescoping arm extends from the central column of the Lunar Lander, grabs a single propellant tank, and pulls it into position. The locks are then released, the Lunar Lander rotates around the Propellant Transporter spacecraft, and the procedure is repeated until all tanks are transferred from one spacecraft to the other. The Lunar Lander can then proceed, fully fueled, to the Moon.

The Propellant Tank Sets

Key elements of the LTS transportation system are the self-contained cryogenic propellant tank sets. A tank set consists of two propellant tanks, a larger liquid hydrogen tank that fits between the top plate and the center plate of the spacecraft, and a smaller liquid oxygen tank that fits between the center plate and the bottom plate of the spacecraft. The liquid hydrogen tanks are 3.0 m in height and .9 m in diameter. The liquid oxygen tanks are 1.25 m in height and .9 m in diameter.

The propellant tanks are light-weight, cylindrical containers. They are designed to withstand an internal pressure of at least one atmosphere in empty space and will be tested to a pressure of three atmospheres on Earth. They are fitted with a waistband for attachment along the periphery of the tanks. Sealed orifices are provided at both ends, an upper one for helium pressurization and a lower one for connection to the propellant feed lines. These orifices are sealed through welded thin diaphragms that are pierced when a propellant flow is required to feed the rocket engine. The propellant tanks will then be completely emptied and then discarded. The tanks are held in place through telescoping grippers that grab each tank by its waistband and holds it on the support plate. The propellant tanks can easily be released from then telescoping grippers and are discarded in space after use.

Propellant Tank Transfer

After two vehicles are solidly connected, the transfer of the fuel tanks can proceed. In weightless space the tanks are held loosley between the plates of the two vehicles. They are also loosely constrained laterally through vertical bars arranged between the tanks. Very little push is now required from the telescoping grip to move the tanks from one vehicle to the other. When a tank arrives midway between the vehicles, the telescoping arm from the receiving vehicle extends toward it; its gripper grabs the tank by its waistband and pulls it into its new berth. This process is repeated until all the tank sets have been transferred from a Propellant Dispenser to a Lunar Lander.

Autonomous Propellant Tank Tapping

The LTS system uses a propellant tank tapping system that enables Lunar Landers to tap into full propellant tanks in cislunar space.
The analogy to beer-keg tapping for access to the propellants is an over simplification of the technology we envision but clearly illustrates the goals of low complexity, low cost, and high reliability. There are many examples of this type of transfer systems for noncryogenic fluids in an Earth environment. The adaptation of these technologies to cryogenic fluids and robotic operations in space is our objective. Tank conceptual designs are being developed in independent system studies.

Both the Lunar Lander and the Propellant Transporter must have access to the propellant tank sets in order to feed their rocket engines. Each tank features two orifices covered with a thin diaphragm, a small one on top for helium pressurization and a larger one on the bottom to draw the cryogenic fuel. A nozzle with a six-bladed knife and flexible seal will then be forced into the two openings to connect them to a helium line and propellant manifold. Only two opposed tank sets will be tapped at a given time, keeping the other tanks for later use. Check valves in each manifold will prevent the fuel from being spilled at tank locations that are not in use.

Autonomous Lunar Landing

The LTS system uses an autonomous lunar landing system that enables the Lunar Landers to land accurately on the lunar surface.
While the Lunar Lander descends toward the lunar surface above the selected landing area, a precision altimeter will measure the height of the vehicle above ground and its vertical velocity. The onboard computer will track these values and figure the exact altitude where, at full engine thrust, the two linear relationships of decreasing vertical velocity and decreasing height above ground will converge to zero simultaneously and cut off the engine at that point. The landing gear will be designed to accommodate an imperfect landing.

Autonomous Payload Offload

The LTS system uses an autonomous payload offload system that lowers payloads from the top of Lunar Lander spacecraft to the lunar surface.

Payloads brought to the surface of the Moon will be transferred in Earth orbit from a Payload Dispenser to the Lunar Lander. The Lunar Lander with extended legs is a tall structure and offloading the payload is a critical task. The payload will be installed on a special Payload Carrier with an extendable overhead arm and a cable that will enable the payload to be lowered to the lunar surface. In early missions to the Moon the Payload Carrier, located on top of the Lunar Lander, will have the ability to gently lower the payload to the ground.

The Payload Carrier is attached through a cable to the telescoping arm. To operate the system, the Payload Carrier contains a power source, an electric motor, and a controller. On signal from the Lunar Lander, the carrier will free the payload, extend an overhead arm, tighten the cable, and then gently lower the payload to the lunar surface. In later operations a mobile crane will be available at the landing sites, tall and stable enough to handle large payloads mounted on top of Lunar Landers.

Trade Studies

LTS has initiated a series of conceptual trade studies for the lunar architecture, ELV payload accommodations, spacecraft design, autonomous rendezvous and docking, autonomous payload transfer, autonomous propellant tank transfer, autonomous propellant tapping, autonomous lunar landing, and autonomous lunar payload offload/onload. Additional conceptual trade studies are planned for 2005.

System Design

Tulane University’s department of Mechanical Engineering is completing trade studies of the LTS baseline design and assessing the requirements for LTS robotics and control systems.

Tulane Engineering Midterm Status Report
Tulane has made excellent progress toward a baseline design. The results from the CAD geometric assessment are consistent with the initial conceptual layout.

Work in Progress:
Preliminary stress analysis to size structural elements of dispenser. Baseline weight and mass property assessment.
Establish baseline latching and releasing mechanism for tanks.
Establish tank transfer path baseline.
Documentation of assumptions and derived requirements.

Lunar Architecture

Gray Research has completed a trade study that evaluates LTS lunar architecture and Lunar flight mechanics.
Gray Research has completed a preliminary analysis of the LTS modular lunar transportation concept, assessed performance and mass characteristics of the Lunar Transportation System, developed concepts of operations for different lunar mission profiles, performed mission safety comparisons with other lunar architectures, and developed configuration sketches to confirm compatibility with existing expendable launch vehicles.

Continuing studies include LTS system concept drawings, lunar flight mechanics analysis, engineering design concepts and mass estimates for expendable launch vehicles, lunar mission profile analysis, and concepts of operations and performance estimates.

The Department of Aeronautics and Astronautics at the University of Washington has contributed to stuidies of lunar flight trajectories for LTS.

Autonomous Rendezvous and Docking

EADS Sodern has completed a trade study that evaluated the use of its ESA ATV autonomous rendezvous and docking system for LTS spacecraft.
EADS Sodern, France, completed a study for LTS evaluating the use of its autonomous rendezvous and docking Videometer system on LTS spacecraft. The study summarizes the capabilities of the Videometer system and the requirements for its implementation on-board LTS spacecraft to permit two LTS spacecraft to rendezvous and dock together.

LTS is currently in negotiations with Optech, Canada, to undertake a similar LTS spacecraft autonomous rendezvous and docking study.

Payload Accommodation

Kistler Aerospace has completed a trade study that evaluated the use of its K-1 reusable launch vehicle to launch LTS spacecraft, propellants, and lunar payloads.
Kistler Aerospace Corporation completed a preliminary study of the use of its K-1 fully reusable launch vehicle to accommodate LTS spacecraft. The study evaluated the capability of the K-1 to launch and deploy LTS spacecraft in LEO, including translunar insertion. The study included payload integration requirements, payload launch environment, payload integration, and launch schedule analysis.

Delta II Heavy payload accommodation and flight dynamics studies are ongoing.

Autonomous Lunar Landing

Optech will be evaluating the use of its Lidar ranging systems for use by LTS Lunar Landers for autonomous lunar landing.

Optech, Canada, will be evaluating the use of its Lidar ranging systems for use by LTS Lunar Landers for autonomous lunar landing.

Lunar trajectory and lunar landing studies are currently underway.

Other Studies

LTS is in the process of commissioning a series of additional conceptual trade studies for the LTS Earth-Moon transportation system.
LTS is developing Statements of Work for a series of additional trade studies that it plans to undertake in 2005, including:

LTS Preliminary Market Assessments

  1. As a project Constellation Systems testbed
  2. To deliver NASA payloads to the Moon
  3. To support NASA’s space exploration plans
  4. To support commercial Lunar activities
  5. To transport lunar resources back to the Earth

LTS Spacecraft Conceptual Design Trade Studies

  1. Spacecraft structure design
  2. Spacecraft propulsion system design
  3. Spacecraft ACS system design
  4. Spacecraft robotics and control systems design

LTS Enabling Technologies - Trade Studies

  1. Hydrogen/oxygen tank design
  2. Propellant tank transfer system design
  3. Propellant tank tapping system design
  4. Payload transfer system design
  5. Lunar landing system design
  6. Lunar payload offload/onload system design

LTS Architecture Trade Studies

  1. Earth-Moon architecture design
  2. Flight dynamics and trajectory analysis

ELV Operations

  1. Payload accommodations
  2. Payload integration
  3. Paylod operations
  4. LTS flight operations
  5. Spacecraft launch orbital phasing

LTS Ground Facilities Design

Schedule

Since the LTS Earth-Moon Transportation system relies on existing and proven ELVs to transport its spacecraft, propellants, and lunar payloads from the Earth to LEO, the LTS development schedule can be shortened when compared to more traditional Earth-Moon architectures that require the development of new heavy-lift launch vehicles.

First LEO flight demonstration missions can begin in Year 4 after Authorization to Proceed (ATP) (see LTS Development Schedule Chart). First direct missions from LEO to the lunar surface with small payloads, can begin in Year 4 after ATP. Lunar landing flights with heavier payloads (requiring refueling in cislunar space) as well as return payloads from the Moon can begin by Year 7 after ATP.

Development Schedule

The development schedule is much faster than currently contemplated schedules because the LTS system uses existing ELVs to launch its spacecraft, propellants, and lunar payloads from Earth to LEO.
Development and deployment of the full LTS system will take only six to seven years after Authorization to Proceed (ATP). This is because the LTS system depends on already existing Earth-to-LEO expendable launch vehicles which are the long poles in the development of any Earth-Moon transportation system. The main items that will take time in the LTS system development are the six enabling technologies and the reconfiguration of the rocket engine that will be used in the fleet of reusable LTS spacecraft.

The first year after ATP will focus on the preliminary design of the LTS spacecraft and spacecraft systems, ground facilities, and operations. Detailed design will take one year, throughout Year 2. LTS spacecraft manufacturing and testing will take one year overlapping Year 2 and Year 3. Ground facilities construction will take five quarters, beginning late in the second year, and be completed by the end of Year 3. Ground facilities and payload integration procedures will take six months in Year 4. The first LTS LEO demonstration flights could occur in year four. A major LEO flight demonstration program will last two and a half years to test launch vehicle deployment capability, LTS spacecraft integrity, systems operations, and operational procedures, and validate LTS enabling technologies. All enabling technologies will be tested and validated in LEO prior to any lunar missions.

The first Lunar landing missions with small payloads can take place as early as Year 5 after ATP, with succeeding heavier payload missions taking place thereafter. The first roundtrip missions to the Moon can take place in Year 7 after ATP.

Flight Demonstration Program Schedule

LTS plans an intensive flight demonstration program in LEO, at L1, in lunar orbit, on the lunar surface, and on return missions from the Moon.
LTS is planning a major flight demonstration Program to demonstrate operations and validate new robotic technologies. The Flight Demonstration Program will test systems, procedures, and new technologies in LEO, in MEO, at L1, in lunar orbit, and on the lunar surface. These missions will utilize LTS spacecraft, that will be launched from the Earth to LEO on a series of Delta II Heavy rockets.

The LTS spacecraft, their subsystems, their rendezvous and docking systems, their payload transfer systems, their propellant tank set transfer systems, their propellant tapping systems, their lunar payload offload/onload systems, and their operational procedures will be tested and validated in this flight demonstration program.

Each flight demonstration mission will build on the one before it. The first series of flight demonstration missions will test and validate LTS systems and technologies in LEO. Once systems and methodologies are validated in LEO, additional flight demonstration missions will be made in cislunar space and, later, on the lunar surface, and on return missions from the Moon.

LTS Concept Validation in LEO

Elements of the LTS concepts to be validated in LEO include:

  1. Delta II Heavy launch integrity and LTS LEO spacecraft deployment.
  2. Autonomous rendezvous and docking between two LTS spacecraft.
  3. Autonomous transfer of Lunar payloads from Payload Dispensers to Lunar Landers.
  4. Transfer of cryogenic propellant tank sets from Propellant Dispensers to Propellant Transporters, and from Propellant Transporters to Lunar Landers.
  5. Tapping propellant tanks in Lunar Landers and Propellant Transporters.
    The second series of flight demonstration missions will further test and validate systems and technologies in LEO and send small payloads of up to 800 kg to the lunar surface.

A third series of flight demonstration missions will refine tests and validate LTS systems and technologies in LEO, and send larger payloads of up to 3 tons to the lunar surface by refueling Lunar Landers at L1.

A fourth series of flight demonstration missions will further refine tests and validate spacecraft systems and technologies in LEO, send larger payloads to the lunar surface by refueling in MEO, L1, and lunar orbit, and return lunar payloads from the Moon to LEO or to the Earth by refueling at one or more of those locations. Refueling frequency and locations will be determined by the size of the payload destined for the Moon or the payload returning to LEO or to the Earth from the Moon.

Cost

The nonrecurring costs to develop the LTS Earth-Moon transportation system are much lower than the cost of developing systems that use more traditional architectures. A significant reduction in Lunar mission costs is the reusability of the major elements of the LTS system, the Lunar Landers and the Propellant Transporters.

The largest cost in operating this system is the delivery of the spacecraft, the propellants, and the Lunar payloads from the Earth to LEO. LTS plans to bring its Earth-Moon transportation infrastructure from the Earth to LEO on existing expendable launch vehicles that are very expensive. Perhaps as much as 70% of the cost of each Lunar mission will be to transport propellants and the LTS infrastructure from Earth to LEO. When propellants can be manufactured on the Moon, Earth-Moon mission costs might be reduced by an 60% or more. If and when fully reusable Earth-to-LEO launch vehicles become available, lunar mission costs might be reduced by an additional 60% or more.

Development Costs

The LTS system will be much less expensive to develop than traditional lunar transportation systems because of its use of existing ELVs and because of the reusability of its lunar spacecraft fleet.

The cost to design, build, test, deploy, and operate the LTS system is currently being analyzed. One thing is clear: Because of the use of existing and proven expendable launch vehicles and the use of existing and emerging technologies, the non recurring costs will be significantly lower than the cost of developing a fleet of new heavy-lift launch vehicles as well as the costs of developing new cutting-edge technologies.

Operation Costs

The recurring cost to operate the LTS Earth-Moon transportation system will be greatly reduced because of the modularity and reusability of its major elements.

The LTS architecture is not simple and depends on the successful development of at least six emerging technologies. But once developed, the LTS architecture provides unique mission flexibility.

The two most expensive spacecraft in the LTS system, the Lunar Lander and the Propellant Transporter, are reusable. While in the short term the operating costs of the LTS system will not differ markedly from the operating costs of more traditional Earth-Moon transportation systems, in the longer term the LTS system will be much cheaper to operate than contemplated architectures. And with reuse comes reliability and safety – two critical factors if and when a scaled-up version of the LTS system is used to transport crews to and from the Moon.

References

Kistler, Walter P., Conceptual Design of an Earth-Moon Spacecraft Fleet. Lunar Transportation Systems, Inc., Bellevue, WA, January 15, 2004.

Kistler, Walter P., The Design of Lunar Transportation Spacecraft. Lunar Transportation Systems, Inc., Bellevue, WA, February 2, 2004.

Kistler, Walter P., Some Design Details of the Propellant Dispenser, the Propellant Transporter, and the Lunar Lander Spacecraft for an Earth-Moon Transportation System. Disclosure document to the US Patent Office, Washington, DC. Lunar Transportation Systems, Inc., Bellevue, WA, February 10, 2004.

Taylor, Tom, Lunar Transportation Spacecraft System Drawings for Patent Application. Lunar Transportation Systems, Inc., Bellevue, WA, February 15, 2004.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, Lunar Transportation Spacecraft System. Provisional Patent Application, No. 60-545,711, submitted to the US Patent Office. Lunar Transportation Systems, Inc., Bellevue, WA, February 18, 2004. Patent pending.

Kistler, Walter P., Design of System Architectures for an Earth-Moon Transportation System. Lunar Transportation Systems, Inc., Bellevue, WA, April 2004.

Kistler, Walter P., Design Details of a Modular, Autonomous, In-Space Cryogenic Propellant Transfer System. Disclosure document to the US Patent Office, Washington, DC. Lunar Transportation Systems, Inc., Bellevue, WA, May 18, 2004.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, Lunar Transportation Spacecraft System. Utility Patent Application to US Patent Office. Lunar Transportation Systems, Inc., Bellevue, WA. In process.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, Details of a Propellant Transfer System. Disclosure document submitted to the US Patent Office. Lunar Transportation Systems, Inc., Bellevue, WA, May 18, 2004.

Kistler, Walter, Bob Citron, and Tom Taylor, An Innovative Earth-Moon Transportation System. Submitted in response to NASAs Exploration Systems Enterprise Request for Information. Lunar Transportation Systems, Inc., Bellevue, WA. May 20, 2004.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, An Earth-Moon Transportation System. White Paper. Lunar Transportation Systems, Inc., Bellevue, WA. First Draft, June 2004.

Kistler, Walter P., Design of a Space Based Cryogenic Propellant Transfer System. Preparation for a US Patent Application. Lunar Transportation Systems, Inc., Bellevue, WA, June 2004.

Kistler, Walter P., Design of a LEO Payload Transfer System. Preparation for a US Patent Application. Lunar Transportation Systems, Inc., Bellevue, WA, June 2004.

Kistler, Walter P., Design of a Lunar Payload Handling System. Preparation for a US Patent Application. Lunar Transportation Systems, Inc., Bellevue, WA, June 2004.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, Details of the Spacecrafts Lunar Transportation System. Disclosure document submitted to the US Patent Office. Lunar Transportation Systems, Inc., Bellevue, WA, May 18, 2004.

Kistler, Walter P., Robert A. Citron, and Thomas C. Taylor, Details of the Propellant Transfer System Lunar Transportation System. Disclosure document submitted to the US Patent Office. Lunar Transportation Systems, Inc., Bellevue, WA, May 18, 2004.

Kistler, Walter, Bob Citron, and Tom Taylor, An Innovative Earth-Moon Transportation System. Submitted in response to NASAs Exploration Systems Enterprise Request for Information. Lunar Transportation Systems, Inc., Bellevue, WA, May 20, 2004.

ATV-VDM Project Presentation File, Document No. LER 00 00405 C - 10, Sodern, Limeil-Brvannes, Paris, France, April 13, 2004.

Kistler, Walter P., and Robert Citron, A Unique Earth-Moon Transportation System. Submitted as part of a response to BAA for Concept Area 1, NASA Office of Exploration Systems. July 15, 2004.

Kistler, Walter P., Robert Citron, and Tom Mobley, Transportation from LEO to Lunar Surface and Return. Submitted in response to RFI-04-HQHS-2, NASA Office of Exploration Systems. July 15, 2004.

Kistler, Walter P., Robert Citron, and Tom Mobley, Lunar Transportation Systems, Inc. Proposal to NASA for Research and Development Opportunities in Human and Robotic Technology. Submitted in response to BAA 04-02, NASA Office of Exploration Systems. September 30, 2004.

Kistler, Walter P., Bob Citron, and Tom Taylor, An Innovative Earth-Moon Transportation System. Abstract submitted to AIAA for the Space Exploration Conference, Orlando, FL, January 30February 2, 2005. Lunar Transportation Systems, Inc., Bellevue, WA, October 30, 2004.

Kistler, Walter P., Bob Citron, and Tom Taylor, Highway to the Moon. Presentation at the NASA Capabilities Workshop, Washington, DC, November 30, 2004.

Kistler, Walter P., and Bob Citron, Highway to the Moon. Strategic Roadmap paper submitted to NASA. Lunar Transportation Systems, Inc., Bellevue, WA, December 2, 2004.

Response to the NASA Draft CEV RFP SOW. Submitted to NASA Office of Exploration Systems, NASA Headquarters, Washington, DC. Lunar Transportation Systems, Inc., December 31, 2004.

Kistler, Walter P., Bob Citron, and Tom Taylor, Commercial Transportation Mission Overviews. Speech to be presented at the 1st Space Exploration Conference: Continuing the Voyage of Discovery, American Institute of Aeronautics and Astronautics, Orlando, FL, January 30-February 1, 2005.

Links

Contact

Lunar Transportation Systems, Inc.
227 Bellevue Way N.E. #259
Bellevue, WA 98004

Phone: (505) 522-2838
Fax: (505) 522-2495
Email: ltspress@earthlink.net
Website : pleine-lune.org