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Nanotechnology and space

Ralph C. Merkle

Principal Fellow, Zyvex

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Three historical trendsin manufacturing

• More diverse• More precise• Less expensive

Overview

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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

Overview

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• Coal• Sand• Dirt, water & air

• Diamonds• Computer chips• Wood

Why it matters

Overview

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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

Over forty years ago

There’s plenty of roomat the bottom

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The book that laid outthe technical argument for

molecular nanotechnology:

Nanosystemsby K. Eric Drexlerpublished in 1992

1980’s and 1990’s

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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

Today

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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.”

Today

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• “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

Definitions

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Possible arrangements of

atoms.

What we can make today(not to scale)

Definitions

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The goal: a healthy bite.

.

Definitions

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• Positional assembly (so molecular parts go where we want them to go)

• Self replication (for low cost)

Fundamental ideas

Nanotechnology

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H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999

Manipulation and bond formation by STM

Positional devices

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Saw-Wai Hla et al., Physical Review Letters 85, 2777-2780, September 25 2000

Manipulation and bond formation by STM

I I

Positional devices

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Theoretical proposal for amolecular robotic arm

Positional devices

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kTkb2

σ: mean positional error k: restoring forcekb: Boltzmann’s constantT: temperature

Classical uncertainty

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kTkb2

σ: 0.02 nm (0.2 Å) k: 10 N/mkb: 1.38 x 10-23 J/KT: 300 K

Classical uncertainty

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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.

Molecular tools

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A hydrogen abstraction tool

http://www.zyvex.com/nanotech/Habs/Habs.html

Molecular tools

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Some other molecular tools

Molecular tools

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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

Molecular tools

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A hydrocarbon bearing

http://www.zyvex.com/nanotech/bearingProof.html

Molecular machines

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http://www.zyvex.com/nanotech/gearAndCasing.html

Molecular machines

A planetary gear

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The Von Neumann architecture

Computer Constructor

http://www.zyvex.com/nanotech/vonNeumann.html

Self replication

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Molecularcomputer

Molecularconstructor

Positional device Tip chemistry

Drexler’s architecurefor an assembler

Self replication

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Self replication

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);}

A C program that prints outan exact copy of itself

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Self replication

Print the following statement twice, the second time in quotes:

“Print the following statement twice, the second time in quotes:”

English translation:

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•Von Neumann'sconstructor 500,000

•Mycoplasma genitalia 1,160,140•Drexler's assembler 100,000,000•Human 6,400,000,000

http://www.zyvex.com/nanotech/selfRep.html

Complexity ofself replicating systems (bits)

Self replication

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An overview of self replicating systemsfor 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

Self replication

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• Nanotechnology is a manufacturing technology

• The impact depends on the product being manufactured

The impact of nanotechnology

The Vision

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• 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

Powerful Computers

The Vision

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• 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

The Vision

http://www.foresight.org/Nanomedicine

Nanomedicine

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• 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.

The Vision

Nanomedicine

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• Killing cancer cells, bacteria• Removing circulatory obstructions• Providing oxygen (artificial red blood cells)• Adjusting other metabolites

The Vision

Nanomedicine

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• By Robert Freitas, Zyvex Research Scientist

• Surveys medical applications of nanotechnology

• Volume I (of three) published in 1999

The Vision

Nanomedicine

http://www.foresight.org/Nanomedicine

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Human impact on the environment depends on

• Population

• Living standards

• Technology

The Vision

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Restoring the environmentwith nanotechnology

• Low cost hydroponics• Low cost solar power• Pollution free manufacturing

The Vision

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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

The Vision

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• New, inexpensive materials with a strength-to-weight ratio over 50 times that of steel

• Critical for aerospace: airplanes, rockets, satellites…

• Useful in cars, trucks, ships, ...

Lighter, stronger,smarter, less expensive

The Vision

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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/

The Vision

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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/

The Vision

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Nanotechnology offers ... possibilities for health, wealth, and capabilities beyond most past imaginings.

K. Eric Drexler

Summation

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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

Quantum uncertainty

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Ground state quantum uncertainty

σ2: positional variance

k: restoring force

m: mass of particle

ħ: Planck’s constant divided by 2π

km22

Quantum uncertainty

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• C-C spring constant: k~440 N/m• Typical C-C bond length: 0.154 nm• σ for C in single C-C bond: 0.004 nm• σ for electron (same k): 0.051 nm

Quantum uncertainty

A numerical example

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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

Molecular mechanics

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Example: H2

Internuclear distance

En

erg

yMolecular mechanics

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Parameters• 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

Molecular mechanics