Fast Rides
Uses of Fusion for
Space Propulsion Systems

Basic Idea of a Rocket
• F = m (d/dt) p
• Rocket equation: vf = u ln(Mi/Mf)
(non-relativistic)
• So, higher exhaust velocity is better
Vrms ~ 10^3 m/s (N2 @ 1000K)
Vfus ~ .086 C (He4 @ 3.5 MeV)
C = 3 x 10^8 m/s

3 types of nuclear rockets
• Nuclear electric, NEP --- Generate
electricity to run another drive, e.g. ion,
photonic (Sanger, others).
• Nuclear thermal, NTP --- heat a secondary
reaction mass.
• Direct nuclear thrust --- use the fusion
products as reaction mass.

Nuclear Thermal Projects
•
•
•
•

Feynman: 1940’s ($1 patent)
NERVA: 1956 – 1971
GSCR: 1960’s
Still viewed by some as engine for Mars
transport (Boeing-NASA study 1990)

Project NERVA/Rover
•
•
•
•
•

1956 --- 1971
USA (Los Alamos and other locations)
250,000 lbs. thrust (best)
Never launched in space; lab work only.
Several projects under ROVER.

http://www.sti.nasa.gov/Pubs/Bulletin/04julypub/hist.html
Courtesy of NASA.

Project PROMETHEUS
• NASA 2003 --- designs for the new Space
Exploration Vision
• Fission NTP, NEP engines.
• Uncertainty over how much longer it will
stay around.

Nuclear thrust rockets
• Fusion reaction directly contributes to
thrust.
• Origin in Project ORION
• Project Daedalus --- 1970’s, UK
• Bussard ramjet
• Mixed with plasma rocket (along lines of
VASIMR)

Project Orion
• Nuclear explosion pulse drive
• Read: blow bombs up behind the ship. Try
not to blow the ship up, too. 1 per sec.
• Plumbbob test – 1957.
• High exhaust v with large force
• Pusher plates -> continual 1-g accel!
• Conventional explosion scale test success.

ORION (con’t)
• Plans for 4000-ton, 1 year round-trip to
Pluto.
• Problem: needed no-fission nukes.
• Killed by atmospheric test-ban treaty,
radiation concerns.

Courtesy of Greg Goebel.

http://www.vectorsite.net/tarokt_2.html

Project Daedalus
• Refinement of Project Orion in a sense
• D-T pellets to be inertially confined and
detonated by an electron beam; explosion
channeled by magnetic field.
• Designed for interstellar
travel (Bernard’s Star)
• 50,000 tons!

Courtesy of Adrian Mann. Used with permission.
www.thespacesite.com/space/future/fusion.php

Bussard Ramjet
• Interstellar space is filled with hydrogen at
low density
• Idea: Collect hydrogen (large magnetic
scoop) and use for your fuel --- don’t need
to bring fuel with you (higher efficiency!)
• Scoop is thousands of square km large
(effective)
• Theoretically able to accelerate well up to
significant fraction of C.

Bussard Ramjet (con’t)
• Possibility of collecting interstellar
antimatter as well.
• Drag and particles a concern.

Courtesy of NASA.

http://www.thespacesite.com/space/images/bussard.jpg

Sources
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

http://en.wikipedia.org/wiki/Orion_project
http://www.u.arizona.edu/~tuvas/Project_orion.html
http://en.wikipedia.org/wiki/Project_Daedalus
http://www.daviddarling.info/encyclopedia/D/Daedalus.html
http://www-spof.gsfc.nasa.gov/stargaze/Snucfly.htm
http://www.daviddarling.info/encyclopedia/P/PrometheusProj.html
http://www.lascruces.com/~mrpbar/rocket.html
http://www.lascruces.com/~mrpbar/Mars%20NTR%2085.pdf
http://www.nasa.gov/centers/glenn/research/warp/ideaknow_prt.htm
http://sbir.gsfc.nasa.gov/SBIR/sbirsttr2002/solicitation/sbir/topic05.html#05.03
Gulevich et al. “Application of Nuclear Photon Engines for Deep-Space Exploration.” Available at
http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APCPCS000552000001000957000001&idty
pe=cvips&prog=normal
http://niac.usra.edu/library --- proceedings of the NASA Institute for Advanced Concepts, annual meetings 19982004.
Mingireanu, Florin. “Ramjet Rocket Engine.” Presented to the NIAC Annual Meeting October 2004. Available
http://niac.usra.edu/files/library/meetings/annual/oct04/Mingireanu_Florin.pdf
McNutt, Ralph et al. “Interstellar Explorer.” Presented to the First International ASI Workshop on Futuristic Space
Technologies, Trieste, Italy 7 May 2002. Available
http://niac.usra.edu/files/library/meetings/misc/trieste_may02_mtg/McNutt_Ralph.pdf
http://www.vectorsite.net/tarokt_2.html
http://www.thespacesite.com/space/images/bussard.jpg
http://www.globalsecurity.org/space/systems/nsi.htm

Sources Continued
•
•
•
•
•
•

http://en.wikipedia.org/wiki/Project_Prometheus
http://trajectory.grc.nasa.gov/projects/ntp/index.shtml
http://www.redorbit.com/news/space/152350/ion_thrusters_propel_nasa_into_future/index.html#121
http://sbir.gsfc.nasa.gov/SBIR/sbirsttr2002/solicitation/sbir/topic05.html#05.03
http://www.nasa.gov/centers/glenn/research/warp/ideaknow.html
www.thespacesite.com/space/future/fusion.php