I

A

SEMINAR REPORT

ON

“Magnetically Launching of Space Vehicle in

Earth’s Lower Orbit”

In partial fulfilment of requirements for the degree of

Master of Technology

In

Instrumentation and Control Engineering

(Specialization - Process Instrumentation)

Submitted By:

BHASE PRASAD SHASHIKANT

MIS NO: 121416017

Under the Guidance of

Dr. S.B. PHADKE

DEPARTMENT OF INSTRUMENTATION AND CONTROL

ENGINEERING

COLLEGE OF ENGINEERING

SHIVAJINAGAR, PUNE-411005

2014 - 2015

II

CERTIFICATE

This is to certify that the Seminar titled “Magnetically Launching of Space Vehicle in

Earth’s Lower Orbit” has been submitted by BHASE PRASAD S. under my guidance in

partial fulfilment of the degree of Master of Technology in Instrumentation and Control

Engineering with specialization in “PROCESS INSTRUMENTATION” of College of

Engineering, Pune during the academic year 2014-2015 (Sem-I) .

Date:

Place: Pune

Guide Head, Instrumentation Department

(Dr. S.B.Phadke) (Dr. S. L. Patil)

III

ACKNOWLEDGMENT

I would like to thank all those who have contributed to the completion of the

seminar and helped me with valuable suggestions for improvement. I would like to

thank Dr. S. B. Phadke, my guide and Dr. S.L. Pati l , Head, Department of

Instrumentation and Control, College of Engineering, Pune, for all help and support

extend to me.

I am extremely grateful to Dr. S.B. Phadke, for providing me with best

facilities and atmosphere for the creative work guidance and encouragement. I

thank all staff members of my college and friends for extending their cooperation

during my seminar. Above all I would like to thank my parents without whose

blessings I would not have been able to accomplish my goal.

IV

ABSTRACT

A Maglev system uses magnetic fields to levitate and accelerate objects along

a track, potentially providing initial vertical velocity prior to rocket ignition allowing

for smaller, lighter rockets. Previous tests have demonstrated that Maglev

technology could accelerate a spacecraft up to 600 mph, and then switch to a

conventional rocket propulsion system near the endpoint of the track. Maglev launch

assist provides many advantages over the conventional rocket launch and the report

presents a system approach documenting the launch assist and compares both

systems, essentially asking the question “would the investment be feasible compared

to conventional solid/liquid rockets?” The report continues analysing the system by

considering engineering challenges of construction, maintenance and power supply.

A case study is performed comparing conventional rocket launch to Maglev launch

assist on the basis of payload lifting capabilities, cost and environmental impacts.

V

CONTENTS

1. Introduction ………………………………………………….….. 1

2. Maglev Technology ………………………………………………3

2.1. Basic Terms ……………………………………………..3

2.1.1. Permanent Magnet ………………………………..3

2.1.2. Electromagnet ……………………………………..4

2.1.3. Superconductive Magnet …………….....................5

2.2. Maglev Principle ………………………………………..6

2.3. Working of Maglev Vehicle …………………………...7

2.3.1. Propulsion Force…………………………………..7

2.3.2. Levitating Force…………………………………...9

2.3.3. Lateral Guidance………………………………….11

3. Design Concepts of Maglev Launch Assist……………………..12

3.1. StarTram Gen-I ………………………………………...12

3.2. StarTram Gen-II ………………………………………..13

3.3. Maglifter ………………………………………………..15

4. Cost Analysis…………………………………………………….17

5. Environmental Impact ……………………………......................19

6. Summary & Conclusion …………………………………………20

7. References ……………………………………….........................21

VI

LIST OF FIGURES

2.1 Permanent Magnetic Field…………………………………3

2.2 Electromagnet……………………………………………...5

2.3 Propulsion Force…………………………………………...8

2.4 EDS System………………………………………………..9

2.5 EMS System……………………………………………….10

2.6 Combined Sketch of Propulsion, Levitation

and Lateral Guidance……………………………………...11

3.1 StarTram Gen-II Levitation Tube…………………………14

3.2 StarTram Gen-II Launch ………………………………….14

3.3 Maglifter Launch Assist Designed at NASA...……………16

LIST OF TABLES

4.1 Cost Analysis of Gen-I,II, Maglifter and Space Shuttle…..17

1

CHAPTER -1

INTRODUCTION

Achieving orbit in space, for both cargo and people is still considered a

great achievement, but in a time of limited budgets the use of conventional rockets

might not be the most efficient method. Placing a kilogram of payload into space

can reach $10, 000[1]. Considering the global economic crisis, space exploration

will be reduced if lower cost technologies fail to replace the current ones. There

are multiple technologies being proposed for space transportation and one of the

most realistic options is magnetic levitation (maglev) launch assist. A maglev

system uses a spacecraft that is magnetically levitated on a track to reduce

friction, and is propelled along the track to high speeds. A maglev train in Japan,

used for passenger transportation can achieve top speeds registered at 581

kilometres per hour (kph). The train’s success demonstrates that the technology

is available, and has the potential to provide an alternative for space exploration.

Compared to conventional rocket launch, the maglev spacecraft launch assist

seems to offer numerous advantages; this report examines the following three:

1) It works on electricity, which significantly reduces the operating costs.

2) It locates its equipment on the ground, which allows placing more payloads

into space.

3) It releases very few chemicals in the atmosphere.

The report presents three existing maglev designs, two developed by

StarTram and NASA’s MagLifter. The report then continues with a comparative

case study of maglev spacecraft system vs. conventional rocket launch. The report

compares these systems based on cost efficiency and environmental footprint. It

then discusses which system is the preferred based on these criteria. The analysis

is not just theoretical, but also describes the exact criteria for a practical maglev

system. The report touches the current global problems: the economic crises and

2

the alarming negative environmental situation. This type of analysis is important

for space exploration because it can demonstrate whether the maglev launch assist

approach is cost feasible compared to traditional rocket launch, and how it meets

the challenges of current environmental challenges.

3

CHAPTER-2

MAGLEV TECHNOLOGY

The creation of magnetic forces is the basis of all magnetic levitation. The

creation of a magnetic field can be caused by a number of things. The first thing

that it can be caused by is a permanent magnet. These magnets are a solid

material in which there is an induced North and South Pole. These will be

described further a little later. The second way that magnetic field can be created

is through an electric field changing linearly with time. The third and final way

to create a magnetic field is through the use of direct current.

2.1 Basic Terms

2.1.1 Permanent Magnet: -

The first type of levitation is the implementation through permanent

magnets. These magnets are made of a material that creates a north and a

south pole on them.

Fig.2.1 Permanent Magnet Field

4

The formal definition of a permanent magnet is “a material that

retains its magnetic properties after and external magnetic field is

removed.”

The whole idea behind permanent magnets is that like ends will

repels and opposite ends will attract. Permanent magnets require very little

if any maintenance. These magnets do not require cryogens or a large

power supply for operation. The magnetic field is measured vertically

within the bore of the magnet.

Disadvantages: -

1. Cost of the magnet is very high when put into large scale systems

2. Varying changes in the magnetic field

3. The ability to control is a constant magnetic force from a permanent

magnet is an ongoing problem

Different applications that use these types of magnets can be found

in a number of different areas. Examples of these applications are

compasses, DC motor drives, clocks, hearing aids, microphones,

speedometers, and many more.

2.1.2 Electro Magnet: -

The basic idea behind an electromagnet is extremely simple. By running

electric current through a wire, you can create a magnetic field. When this wire

is coiled around a magnetic material (i.e. metal), a current is passed through this

wire. In doing this, the electric current will magnetize the metallic core.

5

Fig.2.2 Electromagnet

By using this simple principle, you can create all sorts of things including

motors, solenoids, heads for hard disks, speakers, and so on. An electromagnet

is one that uses the same type of principles as the permanent magnet but only on

a temporary scale. This means that only when the current is flowing is there going

to be an induced magnet. This type of magnet is an improvement to the

permanent magnet because it allows somebody to select when and for how long

the magnetic field lasts. It also gives a person control over how strong the magnet

will be depending on the amount of current that is passed through the wire.

2.1.3 Superconductive Magnet: -

Superconductive magnets are the most common of all the magnets, and are

sometimes called ‘cryomagnets’. The idea behind the superconducting magnets

is that there is a material which presents no electrical resistivity to electrical

current. Once a current has been fed into the coils of this material, it will

indefinitely flow without requiring the input of any additional current. The way

that a material is able to have such a low resistivity to current is that it is brought

to very low temperatures. The temperatures that are commonly found in

superconducting magnets are around -258oC. This is done by immersing the coils

that are holding the current into liquid Helium; this also helps in maintaining a

homogenous magnetic field over time. The advantage to the superconducting

magnet is that they don’t require constant power from a source to keep up the

6

value of the current in the coils. Although a disadvantage is that they require an

expensive cryogen such as helium to operate correctly. The magnetic field is in

the direction of the long axis of the cylinder or bore of the magnet. Since the

resistance in the coils can cause the current to decay, cryogens reduce the

resistance to almost zero, which will help maintain a homogenous magnetic field

over time.

2.2 Maglev Principle: -

Maglev is short for magnetic levitation, which means that these trains will

float over a guide way using the basic principles of magnets.

There are two types of Maglev's: ones that use like magnets which repel

each other and ones that use opposing magnets that attract with each other. Ones

that use repelling magnets are called Superconducting Maglev's. The magnets

allow the train to float. Electromagnetic Maglevs use opposing magnets.

Superconducting Maglevs use very cold temperature magnets in order to

make electricity without any opposition. The magnets are then put on the bottom

of the train. When the train moves, it forms currents from the magnets in the

aluminium sheets placed in the guide way. Because of the repelling force, the

vehicle rises. Also in the guide way, separate electric currents pass through which

push the train forward. This system is also called as ‘ElectroDynamic System.’

Electromagnetic Maglev's go under the guide way. They use opposing

magnets that attract with each other. This allows the Maglev to pull upward

towards the guide way. Like the superconducting Maglev's, separate currents

make magnetic fields shift which allows the train to move forward. These

Maglev's travel about 3/8's of an inch away from the guide way. In order for the

magnets from not hitting the guide way, the lifting current must keep being fixed.

This system also called as ‘ElectroMagnetic System.’

7

The main parts of the Maglev:

1. Guide way and guide rails - keep the train to on track

2. Landing wheels

3. levitation coils - run along the base of the guide way (used in

superconducting maglevs)

4. Emergency landing wheel

5. superconducting magnets and propulsion coils - run along the base of guide

way (used in electromagnetic maglev's)

6. Linear induction motor - moves and brakes the vehicle on the track.

2.3 Working of Magnetic vehicle: -

Basically the construction depends on 3 different working forces.

i. Propulsion Force

ii. Levitating Force

iii. Lateral Guiding Force

2.3.1 Propulsion Force

This is a horizontal force which causes the movement of train. It requires 3

parameters.

i. Large electric power supply

ii. Metal coil lining, a guide way or track.

iii. Large magnet attached under the vehicle.

8

Fig.2.3 Propulsion Force

A linear motor or linear induction motor is essentially a multi-phase

alternating current (AC) electric motor that has had its stator "unrolled" so that

instead of producing a torque (rotation) it produces a linear force along its length.

Many designs have been put forward for linear motors, falling into two major

categories, low-acceleration and high- acceleration linear motors. Low-

acceleration linear motors are suitable for maglev trains and other ground-based

transportation applications. High-acceleration linear motors are normally quite

short, and are designed to accelerate an object up to a very high speed and then

release the object, like roller coasters.

Maglev vehicles are propelled primarily by one of the following three options:

a. Linear synchronous motor (LSM) in which coils in the guide way are

excited by a three phase winding to produce a traveling wave at the speed

desired; Trans Rapid in Germany employs such a system.

b. Linear Induction Motor (LIM) in which an electromagnet underneath the

vehicle induces current in an aluminium sheet on the guide way.

c. Reluctance motor is employed in which active coils on the vehicle are

pulsed at the proper time to realize thrust.

9

2.3.2 Levitating Force

The levitating force is the upward thrust which lifts the object/vehicle in

the air.

There are 3 types of levitating systems

i. EDS system

ii. EMS system

iii. INDUCTRACK system

Levitating force is produced due to the eddy current in the conducting ladder

by the electromagnetic interaction. At low speed the force due to induced poles

cancel each other. At high speed a repulsive force is taken place as the magnet is

shifted over a particular pole.

A. EDS System: -

In EDS both the rail and the train exert a magnetic field, and the train

is levitated by the repulsive force between these magnetic fields. At slow

speeds, the current induced in these coils and the resultant magnetic flux is

not large enough to support the weight of the train. For this reason the train

must have wheels or some other form of landing gear to support the train

until it reaches a speed that can sustain levitation.

Fig.2.4 EDS System

10

On board magnets and large margin between rail and train enable

highest recorded train speeds (581 km/h).This system is inherently stable.

Magnetic shielding for suppression of strong magnetic fields and wheels

for travel at low speed are required. It can’t produce the propulsion force.

So, LIM system is required.

B. EMS System: -

Maglev concepts using electro -magnetic suspension employ

attractive forces. Magnetic fields inside and outside the vehicle are

insignificant; proven, commercially available technology that can attain

very high speeds (500 km/h); no wheels or secondary propulsion system

needed.

Fig.2.5 EMS System

The separation between the vehicle and the guideway must be

constantly monitored and corrected by computer systems to avoid collision

due to the unstable nature of electromagnetic attraction.

C. Inductrack System: -

The inductrack guide way would contain two rows of tightly packed

levitation coils, which would act as the rails. Each of these “rails” would

be lined by two Halbach arrays carried underneath the maglev vehicle: one

positioned directly above the “rail” and one along the inner side of the

“rail”.

11

The Halbach arrays above the coils would provide levitation while

the Halbach arrays on the sides would provide lateral guidance that keeps

the train in a fixed position on the track.

The track is actually an array of electrically-shorted circuits

containing insulated wire. In one design, these circuits are aligned like

rungs in a ladder. As the train moves, a magnetic field repels the magnets,

causing the train to levitate.

2.3.3 Lateral Guidance Force: -

Guidance or steering refers to the sideward forces that are required to make

the vehicle follow the guideway. The necessary forces are supplied in an exactly

analogous fashion to the suspension forces, either attractive or repulsive. The

same magnets on board the vehicle, which supply lift, can be used concurrently

for guidance or separate guidance magnets can be used. It requires the following

arrangements:

• Guideway levitating coil

• Moving magnet

Fig.2.6 combined sketch of Propulsion, Levitation and Lateral Guidance

12

CHAPTER-3

DESIGN CONCEPTS OF MAGLEV LAUNCH ASSIST

The two developed concepts of maglev launch assist are StarTram and

MagLifter.

StartTram is an innovative lunch concept that proposes levitating the

launching track tube high above the earth surface where the air has low density

and allows for lower air drag. The spacecraft placed inside the tube will accelerate

at 8 km per second (kps) enough to place it into the Lower Earth Orbit (LEO).

This is the second generation of StarTram – Gen II – which transports passenger

into space. Gen I is theoretically designed for cargo transportation, and it does

not require a launch tube. Instead it uses a track to be launched from the top of a

mountain at velocities greater than Mach 8. Because Gen II transports passengers

it takes into account the high heating and increased friction, and requires

launching the vehicle at high attitude in a long magnetically levitated tube.

Estimated an elevation of approximately 18 km. [1]

MagLifter is another maglev launch assist concept and was part of the

NASA reusable launch vehicle system. Small scale experiments were conducted

at the NASA Marshall Space Flight Center in Huntsville, USA (Figure I). The

MagLifter spacecraft is escalated on a magnetically levitated sled on a track, and

like Gen I it does not require a tube. The two concepts are described in more detail

below.[3]

3.1 StarTram Gen-I

Gen I system is designed for cargo only, and as mentioned it requires an

acceleration tunnel only. The cargo craft is 2 meters in diameter, 13 meters long

and with a 40 metric ton weight. It is intended to accelerate the craft at 30 G in a

13

~ 100-km length tunnel that is evacuated of air with the help of Magnetic Hydro

Dynamic “window”. The high G level allows building a short acceleration tunnel

and therefore reduces the cost of building the system. The biggest challenge with

operating a short tunnel to high acceleration of 8 kps is the large power storing

and quick power delivery. A good system for electricity operation that allows

both a very short delay between charge and discharge and high power generation

is the superconducting magnetic energy storage (SMES) system. This system can

be designed to include 60 loops of 250 meters in diameter that will allow the

storage of 3,000 Gigajoules (GJ), more than enough to accelerate the 40 metric

ton craft of 1280 GJ. [1]

According to Powell and Maise(Scientists), the potential launch sites for

Gen I have to be close to a low populated area with the minimum flight over land.

This will create a more secure area and less noise disturbance. They also suggest

that the launch attitude is preferable to be at least at an attitude of 4 km in order

to contribute to lower air drag and heating. The last criteria proposed by the author

is a launch into the polar orbits that allows high resolution environmental

monitoring and better survey of all areas around the Earth. The potential launch

site that would meet all the above criteria would be Antarctica.[1]

3.2 StarTram Gen-II

Gen II vehicle is launched from an elevated tube at an altitude of 18 km.

Superconducting wires are buried into the ground and placed on the launch tube.

The repulsive force levitates the tube attached to the Kevlar cables as shown in

the Figure II. The level of 2-3 G is significantly lower than the cargo craft G level

and allows passenger transportation. Because of the slow acceleration Gen II

requires a long track of up to 1600 km as sketched in Figure III. The accelerating

track tube seven meters in diameter consists of the acceleration tube (1280 km

long) at the ground level and the elevated launch tube (281 km long). The current

14

required to levitate four tons per meter is 14 Mega-amps (MA) in the levitated

cables and 280 amps (A) in the ground cables [5]. At a first glance, Gen II seams

to face more engineering challenges then Gen I considering the elevation of a

long tube above the ground. Nevertheless, using Ampere’s force law, the amount

of current needed in the ground superconductors to elevate the tube (around 280

x 106 A) at an attitude of 20-km is 20 times more than current on the tube.

Niobium-titanium superconductors can be resistant enough to deliver this amount

of current with its conventional critical current density of 5 x 105 A/cm2. Because

the power supply required is more than the usual power grid, a power generation

facility is located nearby. The reusable vehicle would return on a horizontal

guideway in the same manner like the Space Shuttle.[7]

Fig.3.1 StarTram Gen-II Levitated tube supported by Kevlar Cable [5]

Fig.3.2 StarTram Gen-II Launch System sketch divided into the long

acceleration tube located on the ground and the elevated part tube 18 km above

the ground [7]

15

3.3 Maglifter: -

The MagLifter is a spacecraft launch system to the LEO created by the

NASA program on Highly Reusable Space Transportation. Compared to other

maglev launch concepts MagLifter does not require extremely high accelerations

and high rates to achieve economical operations. The MagLifter is the next

generation of many “gun” assists ideas, and it consists of launching the vehicle

from a sled that is accelerated on a three to four mile track. The design was

invented, as mentioned, by Mankins who was the manager of Advanced Concept

Studies at NASA in 1994. The architecture of MagLifter system consists of the

following major substructures: the catapult, power systems, structural support

systems and supporting systems:

i. Catapult: - The catapult includes the maglev guideway, the accelerator-

vehicles and the accelerator-carrier staging facility. The accelerator will be

enclosed in a tunnel and will be filled with a helium gas that would allow

low drag forces.

ii. Structural Support: - The structural support will require complicated

engineering design and will depend on whether the guideway is placed on

the exterior of the mountain, on the side of the mountain or in a tunnel

inside the mountain.

iii. Power System: - A substantial local power supply system is needed to

provide enough launch energy that would charge from the local power grid.

16

Fig. 3.3 MagLifter Launch Assist designed at NASA

Marshall Space Flight Center, Huntsville, USA[4]

The reusable vehicle accelerates at 550 miles per hour (885 kph) and at the

end of the guideway, ascends to the Earth orbit and separates from the sled. The

3 G acceleration will allow passenger transportation similar to Gen II. The vehicle

is accelerated efficiently because of the absence of friction between the sled and

the guideway created by the superconducting magnets lined on the sled bottom

and the conductive plates on the guideway. After the launch the sled returns to

the starting point and is reused again for the next launch. Argus, the MagLifter

vehicle is powered by two supercharged ramjet and rocket-based combined-cycle

engines that use liquid hydrogen and liquid oxygen fuels. Argus can be designed

from 170 to 225 feet (52 to 67 m) in length with a 51 to 60 foot (16 to 18 m)

wingspan. The vehicles weights run from 600,000 to 1 million pounds (273,000

kg to 455,000 kg) and can deliver up to 20,000 pounds (9, 000 kg) into the LEO.

Argus returns back as a glider in the same way as the Space Shuttle. The possible

location for the launch facility of MagLifter is the Kennedy Space Center since it

one of the closest U.S. locations to the equator and facing East to the Ocean. [3],

[4]

17

CHAPTER-4

COST ANALYSIS

One primary element of these studies is comparing the investment budget

and the operational costs associated with placing a kilogram of payload into

space. This cost comparison is essential to possible future investment due to the

current global economy.

A detailed cost for StarTram system is proposed by Powell and it is

important to mention that the cost for Gen I includes building two acceleration

tunnels (operational and reserve). The length of both tunnels is twice as long (260

km), therefore the budget for excavating the tunnel will double. In the Gen I

system the spacecraft and the Magnesium diboride (MgB2) are non-recoverable,

so we will move the cost of the MgB2 superconductors to the operational costs

for the final calculations. The detailed budget description of Gen I and Gen II

estimated by Powell is presented in Table I. The MagLifter program estimates a

cost of 2 billion for a large scale project. [6],[7]

The payload delivered to LEO by Endeavour is 24,400 kg and will be used as the

average payload for U.S. Space Shuttle in further calculations.

Table 4.1: Gen I, Gen II, MagLifter and Space Shuttle

Launch Cost/kg of Payload.

18

The investments cost for building MagLifter system seem very low so it is

hard to make any conclusions. Gen I has high operational costs because of the

non-reusable MgB2 superconductors that cost the project around 3 billion extra

each launch. Gen II launch cost is the most convenient because of low operational

costs which is the basic idea of potentially using the magnetic levitation launch

system. Space Shuttle Launch is eight times more expensive than Gen II.

However, this rate is not high enough for a big scale project like spacecraft

launch, and it does not necessarily conclude the cost efficiency of one project

over another. The cost predictions for maglev launch projects are very low, and

so were the NASA initial predictions of Space Shuttle costs. Since Maglev is still

a theoretical concept and it faces many engineering challenges, more research

needs to be performed in order to make accurate final conclusions.

19

CHAPTER-5

ENVIRONMENTAL IMPACT

The maglev spacecraft system’s carbon emissions occur from energy

consumption at the launch stage where the power supply is vast in order to lift the

tube and/or accelerate the spacecraft. Therefore, the most negative impact on the

environment occurs from the emissions produced by the power source.

StarTram does not use engines for launch and so it doesn’t burn fuels [14], while

MagLifter and the Space Shuttle require engines that use liquid hydrogen and

liquid oxygen fuels.

20

SUMMARY AND CONCLUSION

All three systems are similar and different in regards to their engineering

structure and costs. Gen I launched its spacecraft from a track and is accelerated

to 8 kps. The 30 G acceleration does not allow passenger transportation, therefore

the spacecraft is non-reusable. Gen II is a very well though concept that can be

compared to Space Shuttle best since it creates a 3 G acceleration allowing

passenger transportation. The low acceleration and human transportation requires

building a longer tunnel at higher attitudes. The Gen II tube is magnetically

levitated 20 km above the ground where the air is less dense allowing lower

heating and lower air drag. The investment costs for Gen II are higher but the

operational costs lower since the spacecraft is reusable. MagLifter spacecraft is

launched from a sled on a short track (3 km) at a speed of 885 kph, but it uses its

engines for further ascending stages. The concept was experimented before on

small scales at NASA Marshall Space Flight Center, Huntsville, USA.

The costs analysis was done assuming 135 spacecraft launches for the

Space Shuttle. Gen I is a more expensive concept then Gen II because of its higher

operational costs due to the non-reusable spacecraft and MgB2 superconductors

Gen II is a theoretical concept and will require further research of the engineering

challenges.

Based on costs and the environmental impact Gen II is an excellent design

and potentially better than the Space Shuttle. While the cost of maintaining and

operating Gen II are very low.

21

REFERENCES

1. Powell, J.; Maise, G., "StarTram: The Magnetic Launch Path to Very Low

Cost, Very High Volume Launch to Space," Electromagnetic Launch

Technology, 2008 14th Symposium on , vol., no., pp.1,7, 10-13 June 2008

2. J. R. Hull and T. M. Mulcahy, “Magnetically levitated space elevator to

low earth orbit,” in Proc. 3rd International Symposium on Linear Drives

for Industrial Applications, Nagano, Japan, October 2001, pp.42–47.

3. J. H. Schultz, A. Radovinsky, R. J. Thome, B. Smith, J. V. Minervini, R.

L. Myatt, R. Meinke, and M. Senti, “Superconducting magnets for

maglifter launch assist sleds,” IEEE Trans. Appl. Supercond., vol. 11, pp.

1749–1752, 2001.

4. NASA Marshall Space Flight Center

http://www.nasa.gov/centers/marshall/news/background/facts/astp.html_p

rt.htm

5. Spacedaily

http://www.spacedaily.com/news/rlv-99y.html

6. Powell, James, et al. "Maglev Launch: Ultra-low Cost, Ultra-high Volume

Access to Space for Cargo and Humans." Aip Conference Proceedings.

Vol. 1208. No. 1. 2010.

7. Powell, J., George Maise, and John Paniagua. "StarTram: An Ultra-Low

Cost Launch System for Large Scale Exploration and Commercialization

of Space."55th International Astronautical Congress 2004.