A guide to Space Propulsion Techniques.ppt

Space Propulsion Techniques
Present & Future
Asim Pujapanda
04-01-2009

History contd.
• Treaty of Versailles from WW I prohibits
Germany from Long-Range Artillery
• World War II provided the impetus and
motivation for the development of long-
range suborbital rockets
• The most successful were the Germans,
who developed the V-2 (a liquid-
propellant rocket)
• German engineers went to the USSR,US
after the war
• Sputnik 1, by the USSR on Oct. 4, 1957
• Space Race starts..

Kármán line – The
“Edge of space”
•Theodore von Kármán, a Hungarian-
American engineer and physicist
•lies at an altitude of 100 km (62.1
miles) above the Earth's sea level,
•boundary between the Earth's
atmosphere and outer space.
•the Earth's atmosphere becomes too
thin for aeronautical purposes
•there is an abrupt increase in
atmospheric temperature and
interaction with solar radiation

Delta-V Budget
Current/near-term propulsion technology would allow exploration of
the solar system within a “reasonable” time, but won’t work for a
manned interstellar mission within a human lifetime.
Mission (duration) Delta-V (km/sec)
Earth surface to LEO 7.6
LEO to Earth Escape 3.2
LEO to Mars (0.7 yrs) 5.7
LEO to Neptune (29.9 yrs) 13.4
LEO to Neptune (5.0 yrs) 70
LEO to alpha-Centauri (50 yrs) 30,000

Propulsion System Requirements
• Based on Conventional Propulsion Science, here’s what’s needed:
■ Stable and Continuous Thrust, F:
 Vehicle mass, desired acceleration rate and desired final cruising speed will determine the thrust
required.
 Used for slowing down close to destination since gravity-assist would have opposite effect.
■ High Specific Impulse, Isp:
 Generally defined as the time (measured in seconds) to burn one unit mass of propellant while
producing one unit force of thrust.
 Related to exhaust velocity, ve.
 The higher the Isp, the more “propellant-efficient” the engine.
■ High Thrust-to-Weight:
 A high-thrust, low-weight propulsion system yields more manageable vehicle mass and allowable
payload or fuel.
■ Reliability:
 The engine system must be able to withstand the harsh environments and extended duty cycles
required for interstellar missions.

Classification
• Chemical Propulsion Systems
• Electric Propulsion Systems
• Nuclear Propulsion Systems
• Launch Assist Technologies
• Propellentless Propulsion

Chemical Propulsion Systems
F-1 Engine
Saturn V
1.5 million lbs thrust (SL)
LOX/Kerosene
www.flickr.com
Main Engine
Space Shuttle
374,000 lbs thrust (SL)
LOX/H2
spaceflight.nasa.gov

Basic Working of Chemical Propulsion

Liquid propellants
Common liquid fuel combinations in use today:
• LOX and kerosene (RP-1)
• LOX and liquid hydrogen, used in the Space
Shuttle, Ariane 5, Delta IV
• Nitrogen tetroxide (N2O4) and hydrazine
(N2H4). Used in military, orbital and deep
space rockets, because both liquids are
storable for long periods at reasonable
temperatures and pressures.

Types of Liquid Propellants
Monopropellant
• use only one propellant such as hydrazine
(N2H4) & Hydrogen Peroxide (H2O2)
• Widely used for spacecraft attitude and orbit
control

Bipropellants
use a fuel and an oxidizer such as RP-1 and H2O2
• Large variety available (LO2 - LH2, …)Used for
launchers and spacecraft primary propulsion systems

Hypergolic Propellants
• composed of a fuel and oxidizer that ignite when they come into
contact with each other
• no need of an ignition mechanism
• the fuel part normally includes:
Hydrazine, Mono Methyl Hydrazine- MMH, Unsymmetrical Di-Methyl
Hydrazine- UMDH
• The oxidizer is generally Nitrogen tetroxide N2O4 or Nitric acid
HNO3
• easy start and restart capability
• used for orbital insertion as it allows the precise adjustments
required

Alternative Designs of Chemical
Systems
Pulse Detonation Rocket
• Combustion occurs at constant volume instead of constant
pressure (much higher inlet pressure)
• 10% higher thermodynamic efficiency
Rocket Based Combined Cycle
Initial mode –Ejector :Rocket works as compressor stage
for jet engine
Follow up - Ram jet : Rocket engine turned off at Mach 2,
air pressure is high enough


Air Breathing
• Either Rocket Based Combined Cycle or pure rocket mode
uses air breathing
• Air Breathing saves a lot of propellant
• the source of oxidizer is the oxygen from the atmosphere
rather than stored liquid oxygen
• intake vents that “breathe in” oxygen as the vehicle flies

• Initially rockets are used to propel until the air
breathing rockets reach twice the speed of sound
(Mach-2)
• At this stage, atmospheric oxygen would mix with
fuel to propel the vehicle 10 to 12 times the
speed of sound (Mach-10 to Mach-12)
• Air breathing rockets are launched horizontally to
capture sufficient air
• Air-augmented rockets can be used to launch the
air breathing rockets

ELECTRIC PROPULSION SYSTEMS
-While electric thrusters' thrust is weaker compared to chemical thrusters by several
orders of magnitude, it offers much higher specific impulse.
-This is due to the significantly reduced mass flow rate

A guide to Space Propulsion Techniques.ppt

Types of Electric Propulsion
1. Electrothermal propulsion, wherein the propellant is heated by some
electrical process, then expanded through a suitable nozzle
a. Resistojets
b. Arcjets
c. Inductively and radiatively heated devices
2. Electrostatic propulsion, wherein the propellant is accelerated by direct
application of electrostatic forces to ionized particles
a. Ion Thrusters (IT)
b. Field Emission Electric Propulsion (FEEP)
c. Colloidal Thrusters
3. Electromagnetic propulsion, wherein the propellant is accelerated under the
combined action of electric and magnetic fields
a. MagnetoPlasmaDynamic (MPD) Thrusters
b. Hall Thrusters (HT)
c. Pulsed Plasma Thrusters (PPT)
d. Inductive Thrusters

Electrothermal Propulsion
• Principle:
Electro-thermal systems heat propellants, which produce gases.
The gases are then sent through a supersonic nozzle to
produce thrust
Propellant velocity can be calculated similar to chemical propulsion systems

Solar / Laser / Microwave Thermal
Arcjet

Electrostatic Propulsion
• This technique of propulsion utilizes electrostatic energy, i.e.
energy due to electric charges on materials is used to propel
rockets
• also called as ion propulsion technique

• The propellant used in this technique is xenon, a heavy inert
gas
• The propellant is pumped into the ionization chamber where
the propellant atoms get ionized
• In the ionization chamber, electric field provides velocity to
ions
• Ionization is done by electron bombardment
• Two molybdenum grids with a potential of 1,300 volts then
accelerate these xenon ions between them, driving the ions
out the exhaust at over 30 kilometers per second
• The exhaust of the rocket must be neutral

Electrostatic ion thrusters
• highly-efficient low-thrust spacecraft propulsion running on electrical power
• initially developed by Harold R. Kaufman at NASA in the early 1960s
• the NSTAR engine that was used successfully on Deep Space 1
• Hughes Aircraft Company has developed the XIPS (Xenon Ion Propulsion
System) for performing station keeping on geosynchronous satellites
• NASA is currently working on a 20-50 kW electrostatic ion thruster called HiPEP
which will have higher efficiency, specific impulse

Ion Thruster (Xe)
Deep Space-1 Ion Engine Images
launched from Cape Canaveral on October 24, 1998
Although the engine produces just 92 millinewtons of thrust at maximum power (about a
third of an ounce-force), the craft achieved high speeds because ion engines thrust
continuously for long periods. The engine fired for 678 total days, a record for such
engines

Field Emission Electric Propulsion
• FEEP is an advanced electrostatic propulsion concept
• uses liquid metal (usually either caesium or indium) as a
propellant
• consists of an emitter and an accelerator electrode
• field extracts ions, which then are accelerated to high velocities,
typically more than 100 km/s
• very low thrust (in the micronewton to millinewton range),
primarily used for microradian, micronewton attitude control
on spacecraft
• FEEP's unusual combination of very low thrust and very high
specific - unique
• represent the only viable option for drag-free satellite
applications, such as the LISA Pathfinder and Microscope
missions, thrust range (0.1 – 150 µN) is required

Field Emission Electric Propulsion

Colloid Thruster
• A colloid thruster is a type of thruster which uses electrostatic
acceleration of charged liquid droplets for propulsion
• electrospray ionization
• low volatility ionic liquid
• benefits include high efficiency, thrust density, and specific
impulse
• very low total thrust, on the order of μN – same as other ion
thrusters

Key Issue of Ion Thrusters
Grid erosion due to ion bombardment limits thruster lifetime

Hall effect thruster
• Hall thrusters trap electrons in a magnetic field and then use
the electrons to ionize propellant, efficiently accelerate the
ions to produce thrust, and neutralize the ions in the plume
• Hall thrusters are able to accelerate their exhaust to speeds
of around 15–30 km/s, and can produce thrusts of about one
newton
• In a Hall thruster the attractive negative charge is provided by
an electron plasma at the open end of the thruster instead of
a grid

• A radial magnetic field of a few milliteslas is used to hold the electrons in
place

Key Problem of Hall Thrusters
Large plume divergence (~90 deg) decreases thrust and efficiency.
Most importantly, it limits lifetime of the satellite – ion bombardment
damages solar panel dramatically. Outgoing plasma jet may also interfere
with radio-communication between the ground control and the satellite.

Current research on Hall thrusters is ongoing and
focuses mainly on
1.Up scaling the typically 1 kW Hall thruster to
higher powers (50 to 100 kW) and lower powers
(50 to 100 W)
2.Resolving the large plume divergence
3.Enabling operation at higher specific impulse and
variable specific impulse
4.Flight validation
5.Extending the operational lifetimes to enable use
on deep space science missions

Variable Specific Impulse
Magnetoplasma Rocket-VASIMR
• electro-magnetic thruster
• uses radio waves to ionize a propellant and
magnetic fields to accelerate the resulting
plasma to generate thrust
•Conceived by Franklin Chang Diaz at MIT ~1980
•Aiming for Isp of 3,000 – 50,000 sec (exhaust
velocities of 30 – 500 km/sec)
•Efficiency improves with power

• No electrodes or other materials in direct
contact with the plasma.
• Therefore, potential for very high power
density, high reliability, long life.
• Multiple propellants: Helium, Hydrogen,
Deuterium, Nitrogen, Argon, Xenon, others…
• Variable thrust/specific impulse

Applications
• not suitable to launch payloads from the surface
of the Earth due to its low thrust to weight ratio
• drag compensation for space stations.
• lunar cargo transport.
• in-space refueling.
• in space resource recovery.
• ultra high speed transportation for deep space
missions.

NUCLEAR PROPULSION SYSTEMS
• > 9 order of magnitude higher energy density
than chemical
• High energy density leads to very high specific
impulse
• Involves very small quantities of mass ⇒ low
thrust (needs working fluid)
• Enables manned solar system exploration

NERVA (Nuclear Engine for Rocket
Vehicle Application)
• American rocket program, started in 1963, to
develop a thermal nuclear propulsion system
• to take the graphite-based nuclear reactor built
at Los Alamos Scientific Laboratory (LASL) and
create a functioning rocket engine
• program cancelled in 1973, for a variety of
reasons including environmental concerns, loss
of public and political interest
• Program stopped after 2.4 billion US$ funding

The NERVA program started out with the
following objectives :
-multi-mission capability
-minimum 75,000 lb thrust
-endurance of 600 minutes and up to 60
cycles
-capable of 85,000 lb and 500 psi transients
-incorporating adequate shielding for
manned operations
-storable for 5 years on the ground, 6
months on pad, and 3 years in space
-transportable by land, sea, and air

During its lifetime the NERVA program
accomplished the following records:
• highest power: 4500 megawatts thermal power
• 5,500°F exhaust temperature
• 250,000 pounds thrust
• 850 sec. of specific impulse
• 90 min. of burn time
• thrust to weight ratios of 3 to 4

Launch Assist Technologies
• “reach low Earth orbit and you are half way to everywhere”
• reaching Low Earth Orbit (LEO) is the key
• Present-day launch costs are very high — $10,000 to
$25,000 per kilogram from Earth to LEO
• Launching from an aircraft with initial velocity
• Providing initial boost with chemical/electromagnetic
catapult
• Launching outside of the atmosphere on top of an ultra-high
tower
All technologies have up-scaling problems !

Pegasus
• Pegasus rockets are the
winged space booster
vehicles used in an
expendable launch system
• The Pegasus is carried aloft
below a carrier aircraft and
launched at approximately
40,000 ft (12,000 m)
• It is capable of placing small
payloads into low-Earth
orbits

Problem: high-cost and more difficult than
launching directly upward

Space gun
• launching an object into outer space using a large
gun, or cannon
• a space gun has never been successfully used to
launch an object into orbit
• Problems :
- Large accelerations
-Atmospheric drag
-Getting to orbit

Rail Gun
• A rail gun is a purely electrical gun that accelerates a
conductive projectile along a pair of metal rails
• use two sliding or rolling contacts that permit a large electric
current to pass through the projectile
• one million amperes of current will create a tremendous
force on the projectile
• The inductance and resistance of the rails and power supply
limit the efficiency of a railgun design

Space Elevator
• travelling along a fixed structure instead of using rocket
powered space launch
• structure that reaches from the surface of the Earth to
geostationary orbit (GSO)
• Construction would be a vast project
• material that could endure tremendous
stress while also being light-weight, cost-
effective, and manufacturable in great
Quantities -> Current technology not capable
->Possible usage of carbon nanotube-based
materials

Beam-powered propulsion – Laser
Propulsion
• use energy beamed to the spacecraft from a remote power
plant
Conceptual Layout-Photon rocket
• - Directly converts electric energy
into kinetic energy via the use of a
laser
• Laser can heat air and create thrust
• Estimated at 1 MW / kg
• US Air Force is experimenting with small prototype (Lightcraft)

Solar Sail
EADS Astrium's Eurostar E3000 geostationary communications satellites use
solar sail panels attached to their solar cell arrays to off-load transverse
angular momentum

CURRENT STATUS ON PROPULSION
SYSTEMS

AVATAR (Aerobic Vehicle for
hypersonic Aerospace TrAnspoRtation
• single-stage reusable rocketplanes – RLV
• a payload weighing up to 1000 kg to low earth
orbit
• would be the cheapest way to deliver material
to space at about USD 67/kg
• initial development budget
of $5 million
Team of ISRO, DRDO,
23 academic institutions

GSLV-Mk3
• successor to the GSLV
• will use an Indian-developed cryogenic engine
• India will redesign Russian space capsule
Soyuz to send its astronauts on the country's
maiden manned space mission
• It will be launched atop the GSLV-Mk3

Thank You for your attention !

Classification & combinations of
Propulsion Systems

Isp of Chemical Propulsion = 450 sec

Electric Propulsion in US and USSR

A guide to Space Propulsion Techniques.ppt

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