Matter Anti-matter Space Craft Propulsion

8/3/2019 Matter Anti-matter Space Craft Propulsion

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INTRODUCTION

The history of antimatter begins with a young physicist named Paul A.M.Dirac (1902-1984)

and the strange implications of a mathematical equation. This British physicist formulated a

theory for the motion of the electrons in electric and magnetic fields. Such theories had been

formulated before, but what was unique about Diracs was that his included the effects of

Einsteins Special Theory of Relativity. This theory was formulated by him in 1928.Mean while

he wrote down an equation, which combined quantum theory and special relativity, to describe

the behavior of the electron. Diracs equation won him a Nobel prize in I 933,but also posed

another problem; just at the equation x2 = 4 can have two solutions (x 2, x = -2). So Diracs

equation would have two solutions, one for an electron with positive energy, and one for an

electron with negative energy. This led theory led to a surprising prediction that the electron

must have an antiparticle having the same mass but a positive electric charge.

1n1932, Carl Anderson observed this new particle experimentally and it was named positron

This was the first known example of antimatter. In 1955, the anti proton was produced at the

Berkeley Bevatron, and in 1995, scientists created the first anti hydrogen atom at the CERN

research facility in Europe by combining the anti proton with a positron Diracs equation

predicted that all of the fundamental particles in nature must have a corresponding

Antiparticle. In each case, the masses of the particle and anti particle are identical and other

properties are nearly identical. But in all cases, the mathematical signs of some property are

reversed. Anti protons, for example have the same mass as a proton, but the opposite electric

charge.

Since Diracs time, scores of these particle-antiparticle pairings have been observed. Even

particles that have no electrical charge such as the neutron have anti particle.

Rajiv Gandhi Institute of Technology1


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ANTIMATTER PRODUCTION

Anti protons do not exist in nature and currently are produced only by energetic particle

collision conducted at large accelerator facilities (e.g. Fermi National Accelerator Laboratory,

Fermi Lab, in US or CERN in Geneva, Switzerland). This process typically involves

accelerating protons to relativistic velocities (very near to speed of light) and slamming them

into a metal (e.g. Tungsten) target. The high-energy protons are slowed or stopped by collisions

with nuclei of the target; the kinetic energy of the rapidly moving protons is converted into

matter in the form of various subatomic particles, some of which are anti protons. Finally, the

anti protons are electro magnetically separated from the other particles, then they are captured

and cooled (slowed) by a Radio-Frequency Quadrapole (RFQ) linear accelerator (operated as a

decelerator) and then stored in a storage cell called as a Penning Trap.

Note that anti protons annihilate spontaneously when brought into contact with normal matter

thus they must be stored and handled carefully. Currently the highest anti proton production

level is in the order of nano-grams per year.



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ANTIMATTER STORAGE

As we know that the antiprotons annihilate spontaneously when brought into Contact with

normal matter, thus, they must be contained by electromagnetic fields in high vacuums. This

greatly complicates the collection, storage and handling of antimatter. Thus, just after the

production of antiproton they are captured and cooled by a RFQ linear accelerator and then

stored as gaseous plasma of negatively charged antiprotons. The storage cell is called a

Penning trap; it uses magnetic fields to trap charged particles.- These are under development by

Los Alamos National Laboratory (LANL) and Pennsylvania State University (PSU) fore use in

particle physics research experiments.



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However, the storage density of an antiproton plasma in a penning trap is too low to be feasible

for propulsion applications where all of the propulsive energy is derived from matter-antimatter

annihilation. Thus, it is necessary to convert the anti protons into a high-density storage form

such as solid antihydrogen. To do this, positive antielectrons are combined with negative anti

protons to form antihydrogen atoms. This is done in a Paul Trap, which uses oscillating electric

and magnetic fields to trap neutral particles (such as atoms). The atoms are then allowed to

combine to form molecules possibly as clusters of ions and molecules; then the molecules are

cooled to form a solid. Unfortunately, currently only the antiatom production step has been

demonstrated. Still the remaining steps that is conversion of antiprotons to anti atoms to anti

molecules to anti solid H2 has to be demonstrated; this represents one of the major feasibility

issues associated with antimatter propulsion.

PORTABLE ANTIPROTON PENNING TRAP

The picture below shows a schematic and actual photo of the portable antiproton Penning Trap

being developed by Pennsylvania State University (PSU). The Penning Trap was completed in

1996. It is designed to hold 1010 antiprotons. In late 1997, the Penning Trap will be filled

with antiprotons at CERN (Geneva, Switzerland) and transported to the Air Force Phillips

Laboratory SHIVA-STAR facility at Kirkland AFB, where a demonstration of antiproton-

catalyzed micro-fission (but not fusion) is planned for 1997-98. An improved Penning Trap

(with higher capacity) will be assembled in 1998, and used for a demonstration of antiproton-

catalyzed micro-fission and fusion in 1999-2000.

The actual antiproton storage compartment is kept at liquid helium temperatures so as to keep

the antiprotons cool (i.e., so that they wont have enough kinetic energy to escape the

confining magnetic fields provided by the Traps permanent magnets). Thus, the Trap design



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provides for a large outer insulating liquid nitrogen and inner liquid helium volume to permit

trips of several days without cryogen refill.

Finally, note that there is minimal hazard from transporting this small amount of antimatter:

1010 proton-antiproton annihilations, with an annihilation energy content of I .8x 1016 Joules

per kg (0f proton plus antiproton total mass), would only release 0.6 Joules (0.14 calories), or

the energy required to heat one drop (1/20 ml) of water 2.8C.



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ANTI-MATTER PROPULSION

Matter Anti-matter propulsion offers the highest possible physical energy density of any known

reaction substance. The ideal energy density (E = mc2) of 9 x 1016 J/Kg is order of magnitude

greater than chemical (lx 107 J/Kg), fission (8 x 1013 J/Kg) or even fusion (3 x 1014 i/Kg)

reactions. Additionally, the matter antimatter annihilation proceeds spontaneously, therefore not

requiring massive or complicated reactor systems. These properties make antimatter very

attractive for propulsive ambitious space missions. This section describes antimatter propulsion

concepts in which matter antimatter annihilation provides all of the propulsive energy.

Once produced and stored, antimatter can annihilate with normal matter to produce energy for

propulsion. The annihilation produces tremendous energy in the form of energetic, unstable

charged and neutral sub atomic particles (mostly pions,p). Note that for a propulsion

application, proton antiproton annihilation is preferred over electron positron annihilation

because the products of proton antiproton annihilation are charged particles that can be confined

directed magnetically so as to transfer their energy to propulsive working fluid like normal

H2. By contrast, electron-positron annihilation produces only high-energy gamma rays, which

do not couple their energy efficiently to a working fluid. Thus, in the annihilation of proton

(p+) and the antiproton (p-), the products include neutral and charged pions (p0, p+, p-). In this

case, the charged ions can be trapped and directed by magnetic fields to produce thrust

However, pions do possess mass, so not all of the proton antiproton mass is converted into

energy. This results in an energy density of the proton antiproton reaction of only 1.8 x l0l6J/Kg.

To implement an antimatter rocket engine, the three main components required are antimatter

storage system, feed system and thruster. In this fig. the antimatter is stored in the form of solid

pellets of anti hydrogen. A high-density form of antimatter is required because storage as

gaseous plasma in a Penning Trap is limited to about 1010 particles per cubic centimeter; the

volume of 10mg of antimatter would be equivalent to 40 space shuttle cargo bays.



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However storage as a solid requires low temperature to prevent sublimation of the pellets.

Gaseous antihydrogen could not be contained; only the solid (or liquid) is diamagnetic and can

be levitated by a magnetic field. Also, very high- quality vacuum in the storage chamber is

required to prevent residual normal matter gas annihilating on the solid antihydrogen pellets

For eg. , in the image, both a vacuum pump and a series of air lock doors are required to prevent

gas from the thruster entering the storage chamber. Finally normal hydrogen is used as the

propellant working fluid; an excess of hydrogen is used such that the annihilation energy

between a small amount of antihydrogen and normal hydrogen heats a large mass of normal

hydrogen. This annihilation is accomplished inside the thruster.



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ANTIMATTER THRUSTER CONCEPTS

There are four basic antimatter thruster concepts to harness matter antimatter annihilation

energy for propulsion. They are the solid-core, gas-core, plasma-core and beam-core thrusters.

The solid-core thruster is similar in concept to nuclear rocket. Antiprotons annihilate inside a

solid core heat exchanger made of tungsten or graphite. The annihilation heats the core, which

in turn heats hydrogen propellant flowing through the core. The heated 142 then expands

through a conventional nozzle to produce thrust. This device is very efficient and produces high

thrust, but the specific impulse is limited to less than 1000 lbf-s/lbm due to material constraints.

In the gas-core device, antimatter is annihilated directly in the H2 propellant to be exhausted

Magnetic fields are used to contain only the energetic charged pions (p+, p-) which spiral into



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the H2 gas to heat it. The heated 1-12 is then expanded through a conventional rocket engine

The device is less effective or less efficient than the solid-core concept but could possibly

achieve higher specific impulse in the range up to 2500 lbf-s/lbm.

The plasma-core thruster, which is similar to earlier one but operates by annihilating larger

amounts of antimatter in H2 to produce hot plasma. The plasma is confined in a magnetic bottle

configuration, which also contains the energetic charged pions, which heat the plasma. To

produce thrust, the heated plasma is then exhausted through one end of the magnetic bottle

Since this device uses magnetic fields for plasma confinement, it is not limited in temperature

by material melting points. It can therefore achieve much higher specific impulse in the range of

5000 to 100,000 Ibf-sllbm at useful thrust levels.

Lastly, the beam-core thruster employs a diverging magnetic field just upstream of the

annihilation point between the antimatter and low density H2. The magnetic field is then

directly focuses the energetic charged pions as the as the exhausted propellants. Thus the

charged pions are traveling close to the speed of light, the specific impulse of the device could

possibly range as high as l0 lbfs/Ibm, but at very low thrust levels.



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ANTIMATTER ROCKET FOR INTERSTELLAR MISSIONS

This image represents an antimatter rocket with a beam-core thruster. The long length of the

vehicle is required due to the lona distance that the proton antiproton annihilation products

travel (because the decay products are moving at nearly the speed of light). For eg the initial

proton antiproton annihilation produces, on an average 1.6 neutral (p) and 3.2 charged

pions (p, p)

P+ + P- 1.6pO 3.2p+, p-

The neutral pion rapidly decays into high-energy gamma rays (g), which are effectively useless

for propulsion

p2gThe charged pions, on the other hand, have a longer life time and travel on the order of 21 m

before decaying into charged muons (i, f) and neutrons (n); the charged muons travel an

additional 1.85km before decaying into electrons (e or positrons (e and neutrinos.



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INERTIAL CONFINEMENT FUSION (ICF) PROPULSION

Inertial confinement fusion (ICF) requires high-power lasers or particle beams to compress and

heat a pellet of fusion fuel to fusion ignition conditions. In operation, the pellet of fusion fuel

(typically deuterium-tritium, D-T) is placed at the locus of several high-power laser beams or

particle beams. The lasers or particle beams simultaneously compress and heat the pellet

Compression of the pellet is accomplished by an equal and opposite reaction to the outward

explosion of the surface pellet material. Heating of the pellet results from both the compression

and the inputted laser energy (or particle-beam kinetic energy). The pellets own inertia is

theoretically sufficient to confine the plasma long enough so that a useful fusion reaction can be

sustained; hence this fusion reaction is inertially confined.

Unfortunately, from a spacecraft perspective, lasers and particle beam ICF implosion drivers

are heavy, electric-power intensive systems. In an attempt to avoid these drawbacks, several

alternative concepts have been proposed. One simple solution is to take the lasers off of the

vehicle and place them in a remote location (e.g., Earth orbit) and beam the laser energy to the

vehicle. Several chemical drivers have also been considered. For example, high-energy

chemical explosives or high energy density matter (FDM) metastable species (e.g., metaslable

helium) could be applied to the surface of the fusion fuel pellet and triggered to produce an

implosion. Also, macroscopic kinematic dnvers (basically high-speed hammers) have been

modeled. Finally, the most exotic approach is a variation on the Interstellar Ramjet; in this

concept, fusion fuel pellets are fired (from Earth orbit using a mass driver or rail gun) Out ahead

of the vehicle. At sufficiently high speeds, the relative velocity of impact between the vehicle

and the pellet is sufficient to cause ignition.



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VISTA SPACECRAFT

The inertial confinement fusion (ICF) reaction can e used to provide useful thrust for space

travel. This has been proposed in .5 concept called VISTA (Vehicle for Interplanetary Space

Transport Applications). (A closely related concept uses a small amount of antimatter to trigger

a micro-fission/fusion reaction.) In the VISTA ICF propulsion concept. a fraction of the fusion

reaction energy produced is converted to electric power and u5ed to operate the laser (or

particle beam) pellet implosion driver modules. A super conducting ring magnet at the base of

the cone produces a magnetic nozzle, which directs the flow of the fusion plasma debris to

produce thrust. The fusion pulse occurs at the apex of a 500 half-angle cone. The unique

hollow-cone configuration of the vehicle is chosen so that a ring-shaped radiation shield 15-rn

from the apex protects the rest of the vehicle in a conical radiation shadow.

The below image illustrate the VISTA ICF spacecraft The red tubes are the driver lasers; the

white rectangular boxes between the lasers are the power processors. Mirrors used to focus

the laser light onto the fusion pellet are on the standoffs (the mirrors are just visible in the

picture). The VISTA hydrogen propellant tank is the ring-shaped bulge at the top of the vehicle

(base of cone). Above this are cylindrical habitat modules and conical aero shell (Apollo-

shaped) landers. Finally, note that the tethered astronaut (shown in the vehicle at Mars picture)



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is grossly out of scale; the vehicle is on the order of 100 m tall and 170 m in diameter (at the

base of the cone)

VISTA (and all ICF systems) is operated in a pulsed mode. The VISTA vehicle sized for a fast

(60 day round trip) manned-Mars mission (100 metric tons [MT] payload) has a total weight of

5800 MT tons, of which 4100 MT is hydrogen expellant, and 40 MT is DT fuel. It produces ajet

power of 30,000 MW at 30Hz operation (30 DT pellets are ignited per second in the magnetic

thrust chamber), and a specific impulse of 17,000 lbf-s/lbm (166,600 m/s). This concept design

is based on assumptions regarding the success of present inertial confinement fusion research

efforts and on spacecraft technology expected to be available by the year 2020. The VISTA

study participants included Lawrence Livermore National Laboratory (LLNL), Jet Propulsion

Laboratory (JPL), Energy Technology Engineering Center (ETEC), and Johnson Space Center

(JSC).

VISTA SPACECRAFT CONCEPT



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DAEDALUS SPACECRAFT

The British Interplanetary Society conducted a design study to evaluate the feasibility of inertial

confinement fusion (ICF) propulsion for interstellar travel. The vehicle was called Daedalus and

was designed for an interstellar flyby with a total DV of 0.1 c. Daedalus was engineered as a

two-stage vehicle ith a total mass at ignition of 53,500 MT. The first stage carries 46,000 MT

of propellant and has a dry mass of 1690 MT; it produces a thrust of 7.5 x 106 N and has an



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ignition rate of 250 pellets/second. The burn time is estimated to he about 2 years. The second

stage carries 4000 MT of propellant and has a dry mass of 980 Mg. Second-stage thrust is 6.6 x

105 N at an ignition rate pf 250 pellets second; its bum time is estimated to be about 2 years.

The final net payload is S30 MT. The specific impulse for each stage is approximately 106 lbf-

s/lbm (10 mis, or 0.03 c).

ANTIPROTON-CATALYZED MICRO-FISSION/ FUSION PROPULSION

Previous studies have identified fusion propulsion as an enabling technology. for rapid human

transportation within the solar system and potentially for interstellar missions. In particular,

fusion propulsion is especially attractive for fast round trip) piloted Mars missions. For

example, in the VISTA (Vehicle for Interplanetary Space Transportation Applications) study

an inertial co-.fteiflct1t fusion (ICF) propulsion system was found capable of performing a 60-



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d round- trip Mars mission with a 100-MT payload. This type of performance is typical of

fusion rockets, although it requires large vehicles (1600-MT dry without payload, 4100-MT

of propellant), operating at high powers (30 GW and high Isps (17,000 lbf-s/lbm or 166,600

m/s).

An alternative approach to conventional VISTA-type fusion propulsion systems is the inertial-

confinement antiproton-catalyzed micro-fission fusion nuclear (ICAN) propulsion concept

under development at Pennsylvania State University (PSU). In this approach to ICF propulsion

a pellet containing Uranium(U) fission fuel and deuterium-tritium (D-T) fusion fuel is

compressed i lasers, ion beams, etc. At (he time of peak compression, the target is bombarded

with a small number (108-1011) of antiprotons to catalyze the uranium fission pr0Ce55. (For

comparison, ordinary U fission produces 2 to 3 neutrons per jsLOi1 by contrast, antiproton-

induced U fission produces 16 neutrons per fission. The fission energy release then triggers a

high-efficiency fusion burn to the propellant, resulting in expanding plasma used to produce

thrust. Significantly, unlike pure antimatter propulsion concepts which require large amounts

of antimatter (because all of the propulsive energy is supplied by matter- antimatter

annihilation), this concept uses antimatter in amounts that we can produce today with existing

technology and facilities. This technology could enable 100- to 130-day round trip (with 30-day

stop-over) piloted Mars missions, 1 .5-year round trip (with 30-day stop-over) piloted Jupiter

missions, and 3-year one-way robotic Pluto orbiter mission (all with 100 MT payloads).



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Also, because much of the fusion ignition energy comes from the initial fission reaction, it may

be possible to employ smaller or simpler pellet compression drivers (e.g., particle beams

lasers, etc.) than those considered for a conventional ICF system where all of the fusion

ignition energy is derived from the compression process. Similarly, it may also be possible to

use difficult-to- ignite aneutronic fuels like D-He3. For example, recent simulations of D-He3

versus D-T antiproton-catalyzed micro-fission/fusion have shown that although neutron energy

yields are reduced by a factor of 5 using D-He3, the fusion energy yield is 12 times smaller than

that with D-T due to the slow burn rate of the DHe3 target (which allows time for disassembly

of the target before it can be consumed). However, neutron flux with D-He3 may result in

reductions in overall vehicle mass (due to decreased shielding, waste-heat control, etc

requirements) may compensate for the reduced fusion energy yield.

Concept

I Uranium (or Pu) enriched DT .(or D-He3) pellet compressed (by ions, lasers, etc.)

2.At the time of peak compression, the target is bombarded with a small number.

(-..108) of antiprotons to catalyze fission.

3. The fission energy release triggers a high-efficiency fusion burn to heat the

Propellant.

4. Resulting expanding plasma used to produce thrust.

Features



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I. Uses s small amount of antimatter - an amount that we can produce today with

existing technology and facilities.

2. Mission benefits of 120-day Earth-Mars round trip.

3. Potential benefits of easier drivers/aneutronic fuels.

Feasibility Issues

1. Pellet implosion dynamics

2. Fission bum up (number of antiprotons needed)

3. Fus ion ignition and bum (total gain)

4. Transfer of fission/fusion energy to propellant

5. Transfer of propellant energy to vehicle



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ICAN PROPULSION VEHICLE

The following picture shows the inertial-confinement antiproton-catalyzed micro- fission/fusion

nuclear (ICAN) propulsion concept vehicle, which employs the antiproton-catalyzed micro-

fission/fusion concept under development at Pennsylvania State University (PSU). (This is the

second and most recent configuration, thus it is called ICAN-Il.)

The system has several similarities to the ORION pulsed fission propulsion concept because

each micro-fission/fusion explosion releases an energy equivalent to 20 tons of TNT. Thus, ashock absorber system is used to couple



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the propulsive pulses to the rest of the vehicle. Also in this configuration, the antiprotons are

contained in storage rings (essentially recreating) on a small scale the large storage rings at

FermiLab or (CERN). Finally, the crew compartments are located as far as possible from the

fission/fusion reaction to minimize shielding requirements. (The crew compartments are also

spun to provide artificial gravity.)

ICAN PROPULSION VEHICLE ENGINE

The above picture shows the engine portion of the inertial confinement antiproton-catalyzed

micro-fission/fusion nuclear (JCAN) propulsion concept vehicle, which employs the antiproton



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catalyzed micro-fission/fusion concept under development at Pennsylvania State University.

(This is the second and most recent configuration, thus it is called ICAN II).

The system has several similarities to inertial confinement fusion (ICF) propulsion concepts.

For example, there is a particle beam (rather than laser- beam) driver that compresses the

micro-fission/fusion pellet prior to injection of antiprotons. After the micro-fission/fusion

explosion which releases an energy equivalent to 20 tons of TNT, the expanding plasma ablates

a layer of lead on the inside cup of the thrust chamber. In fact, most of the total propellant

mass is lead. Lead is used so as to efficiently capture the energy released the micro-

fission/fusion explosion (which is in the form of-various, forms of high-energy photons and

particles) and convert this energy into directed propulsive thrust.



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ADVANTAGES

I. When antimatter comes into contact with normal matter, these equal but opposite particle

collides to produce an explosion emitting pure radiation. This explosion transfers the entire

mass of both objects into energy, which is believed to be more powerful than any that can be

generated by other propulsion system.

II. In ICAN propulsion vehicle, a small amount of antimatter is used to trigger the micro-

fission/fusion reaction. Thus the antimatter acts as a catalyst to drive another reaction.

LIMITATIONS

I. As we know that antiprotons annihilate spontaneously when brought into contact with normal

matter, thus they must be contained by electromagnetic fields in high vacuums. This greatly

complicates the collections, storage and handling of antimatter. Thus storage is the greatest

limitation.

II. Finally, current production technology has an energy efficiency of about an order of

nanograms per year. This is very small compared to the mission propulsion requirement for

antimatter, which requires milligrams of antimatter for simple orbit transfer maneuvers and up

to tons of kilograms of antimatter for near star interstellar flybys.

HI. During the matter anti-matter annihilation, some amount of gamma rays is produced. These

rays are harmful to the onboard passengers/crews traveling in it. Research is going on to rectify

it.



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CONCLUSION

Currently, just 14 nanograms of antiprotons would be enough fuel to send a manned spacecraft

to Mars in one month. Today it takes nearly a year for an unmanned spacecraft to reach Mars.

Scientists believe that the speed of a matter- antimatter powered spacecraft would allow man to

go where no man has gone before in space. Meanwhile lots of research & studies are going on

to use the small fraction of antimatter available on earth (which where artificially produced) to

trigger the micro fission) fusion reaction in an ICAN propulsion vehicle. Anyhow, after some

decades it would be possible to make trips to Jupiter and even beyond the heliopause, the point

at which the suns radiation ends.

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Matter Anti-matter Space Craft Propulsion