Transcript Nanotechnology and space Ralph C. Merkle Principal Fellow, Zyvex Overview Three historical trends in manufacturing • More diverse • More precise • Less expensive.

Nanotechnology and
space
Ralph C. Merkle
Principal Fellow, Zyvex
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Overview
Three historical trends
in manufacturing
• More diverse
• More precise
• Less expensive
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Overview
The limit of these trends:
nanotechnology
• Fabricate most products consistent with
physical law
• Get essentially every atom in the right place
• Inexpensive (less than $1/kilogram)
http://www.zyvex.com/nano
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Overview
Why it matters
• Coal
• Sand
• Dirt, water & air
• Diamonds
• Computer chips
• Wood
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Over forty years ago
There’s plenty of room
at the bottom
The principles of physics, as far as I
can see, do not speak against the
possibility of maneuvering things atom
by atom.
Richard Feynman, 1959
http://www.zyvex.com/nanotech/feynman.html
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1980’s and 1990’s
The book that laid out
the technical argument for
molecular nanotechnology:
Nanosystems
by K. Eric Drexler
published in 1992
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Today
National Nanotechnology Initiative
• Announced by Clinton at Caltech
• Interagency (AFOSR, ARO, BMDO,
DARPA, DOC, DOE, NASA, NIH, NIST,
NSF, ONR, and NRL)
• FY 2001: $497 million
http://www.whitehouse.gov/WH/New/html/20000121_4.html
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Today
President Clinton on the NNI
“Imagine the possibilities: materials with ten
times the strength of steel and only a small
fraction of the weight -- shrinking all the
information housed at the Library of
Congress into a device the size of a sugar
cube -- detecting cancerous tumors when
they are only a few cells in size.”
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Definitions
• “Nanotechnology” has been applied
broadly to almost any research where
some dimension is less than a micron
(1,000 nanometers) in size
• “Molecular nanotechnology” is focused
specifically on inexpensively making
most arrangements of atoms permitted
by physical law
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Definitions
Possible
arrangements of
. atoms
What we can make today
(not to scale)
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Definitions
The goal:
a healthy bite.
.
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Fundamental ideas
Nanotechnology
• Positional assembly (so molecular parts
go where we want them to go)
• Self replication (for low cost)
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Positional devices
Manipulation and bond formation by STM
H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999
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Positional devices
I
I
Manipulation and bond formation by STM
Saw-Wai Hla et al., Physical Review Letters 85, 2777-2780, September
25 2000
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Positional devices
Theoretical proposal for a
molecular robotic arm
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Classical uncertainty
kbT
 
k
2
σ:
k:
kb:
T:
mean positional error
restoring force
Boltzmann’s constant
temperature
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Classical uncertainty
kbT
 
k
2
σ:
k:
kb:
T:
0.02 nm (0.2 Å)
10 N/m
1.38 x 10-23 J/K
300 K
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Molecular tools
Synthesis of diamond today:
diamond CVD
• Carbon: methane (ethane, acetylene...)
• Hydrogen: H2
• Add energy, producing CH3, H, etc.
• Growth of a diamond film.
The right chemistry, but little control over the site
of reactions or exactly what is synthesized.
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Molecular tools
A hydrogen abstraction tool
http://www.zyvex.com/nanotech/Habs/Habs.html
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Molecular tools
Some other molecular tools
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Molecular tools
A synthetic strategy for the
synthesis of diamondoid structures
• Positional assembly
(6 degrees of freedom)
• Highly reactive compounds (radicals,
carbenes, etc)
• Inert environment (vacuum, noble gas) to
eliminate side reactions
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Molecular machines
A hydrocarbon bearing
http://www.zyvex.com/nanotech/bearingProof.html
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Molecular machines
A planetary gear
http://www.zyvex.com/nanotech/gearAndCasing.html
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Self replication
The Von Neumann architecture
Computer
Constructor
http://www.zyvex.com/nanotech/vonNeumann.html
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Self replication
Drexler’s architecure
for an assembler
Molecular
computer
Molecular
constructor
Positional device
Tip chemistry
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Self replication
A C program that prints out
an exact copy of itself
main(){char q=34, n=10,*a="main() {char
q=34,n=10,*a=%c%s%c;printf(a,q,a,q,n
);}%c";printf(a,q,a,q,n);}
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Self replication
English translation:
Print the following statement twice, the
second time in quotes:
“Print the following statement twice, the
second time in quotes:”
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Self replication
Complexity of
self replicating systems (bits)
•Von Neumann's
constructor
•Mycoplasma genitalia
•Drexler's assembler
•Human
500,000
1,160,140
100,000,000
6,400,000,000
http://www.zyvex.com/nanotech/selfRep.html
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Self replication
An overview of self replicating systems
for manufacturing
• Advanced Automation for Space Missions,
edited by Robert Freitas and William Gilbreath
NASA Conference Publication 2255, 1982
• A web page with an overview of replication:
http://www.zyvex.com/nanotech/selfRep.html
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The Vision
The impact of nanotechnology
• Nanotechnology is a manufacturing
technology
• The impact depends on the product being
manufactured
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The Vision
Powerful Computers
• We’ll have more computing power in the
volume of a sugar cube than the sum total
of all the computer power that exists in the
world today
• More than 1021 bits in the same volume
• Almost a billion Pentiums in parallel
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The Vision
Nanomedicine
• Disease and ill health are caused largely
by damage at the molecular and cellular
level
• Today’s surgical tools are huge and
imprecise in comparison
http://www.foresight.org/Nanomedicine
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The Vision
Nanomedicine
• In the future, we will have fleets of surgical
tools that are molecular both in size and
precision.
• We will also have computers much smaller
than a single cell to guide those tools.
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The Vision
Nanomedicine
•
•
•
•
Killing cancer cells, bacteria
Removing circulatory obstructions
Providing oxygen (artificial red blood cells)
Adjusting other metabolites
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The Vision
Nanomedicine
• By Robert Freitas, Zyvex Research
Scientist
• Surveys medical applications of
nanotechnology
• Volume I (of three) published in 1999
http://www.foresight.org/Nanomedicine
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The Vision
Human impact on the
environment depends on
• Population
• Living standards
• Technology
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The Vision
Restoring the environment
with nanotechnology
• Low cost hydroponics
• Low cost solar power
• Pollution free manufacturing
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The Vision
Military applications of molecular
manufacturing have even greater potential
than nuclear weapons to radically change
the balance of power.
Admiral David E. Jeremiah, USN (Ret)
Former Vice Chairman, Joint Chiefs of Staff
November 9, 1995
http://www.zyvex.com/nanotech/nano4/jeremiahPaper.html
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The Vision
Lighter, stronger,
smarter, less expensive
• New, inexpensive materials with a strengthto-weight ratio over 50 times that of steel
• Critical for aerospace: airplanes, rockets,
satellites…
• Useful in cars, trucks, ships, ...
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The Vision
Space
• Launch vehicle structural mass could be
reduced by a factor of 50
• Cost per kilogram for that structural mass
could be under a dollar
• Which will reduce the cost to low earth
orbit by a factor 1,000 or more
http://science.nas.nasa.gov/Groups/Nanotechnology/
publications/1997/applications/
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The Vision
Greater function per
unit weight
• Computers and sensors will weigh less
per unit mass
• Greater functionality per pound, further
reducing cost per function
http://science.nas.nasa.gov/Groups/Nanotechnology/
publications/1997/applications/
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Summation
Nanotechnology offers ...
possibilities for health, wealth,
and capabilities beyond most
past imaginings.
K. Eric Drexler
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Quantum uncertainty
Born-Oppenheimer approximation
• A carbon nucleus is more than 20,000 times as
massive as an electron
• Assume the atoms (nuclei) are fixed and
unmoving, and then compute the electronic
wave function
• If the positions of the atoms are given by r1, r2,
.... rN then the energy of the system is:
E(r1, r2, .... rN)
• This is fundamental to molecular mechanics
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Quantum uncertainty
Ground state quantum uncertainty

 
2 km
2
σ2:
k:
m:
ħ:
positional variance
restoring force
mass of particle
Planck’s constant divided by 2π
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Quantum uncertainty
A numerical example
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C-C spring constant:
Typical C-C bond length:
σ for C in single C-C bond:
σ for electron (same k):
k~440 N/m
0.154 nm
0.004 nm
0.051 nm
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Molecular mechanics
Basic assumptions
• Nuclei are point masses
• Electrons are in the ground state
• The energy of the system is fully
determined by the nuclear positions
• Directly approximate the energy from the
nuclear positions, and we don’t even
have to compute the electronic structure
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Molecular mechanics
Energy
Example: H2
Internuclear distance
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Molecular mechanics
Parameters
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Internuclear distance for bonds
Angle (as in H2O)
Torsion (rotation about a bond, C2H6
Internuclear distance for van der Waals
Spring constants for all of the above
More terms used in many models
Quite accurate in domain of
parameterization
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