‹#›

GP-B, 2004-2005 Relativity Mission, Gravity Probe B

STAR 2015 Space Time

Asymmetry Research

LISA, 2025 Laser Interferometer Space Antenna

Gravitational Physics

Experiments in Space

Sasha Buchman Stanford University

Lisbon & Porto, 2010

‹#›

George Bernard Shaw 1930

Ptolemy made a universe which lasted 1400 years,

Newton also made a universe which has lasted 300 years,

Einstein has made a universe and I can’t tell you how long that will last

Napoleon and other

great men of his

type, they were

makers of empire,

but there is an order

of men who get

beyond that.

They are not

makers of empires,

but they are makers

of universes.

And when they

have made those

universes, their

hands are unstained

by the blood of any

human being on

earth.

‹#›

Outline

Why Test Gravity ?

How To Test Gravity ?

Why Space ?

General Relativity, GP-B

Lorentz Invariance, STAR

Gravitational Waves, LISA

Gravity

Strong Nuclear Force

Weak Nuclear Force

Electro Magnetism

Balloon experiment

GP-B

LISA

STAR

‹#›

How Well Is GR Tested

Einstein's 2½ tests

Perihelion of Mercury, light deflection, redshift ( ½ test)

Test enabled by new technologies since 1960 Clocks, electromagnetic waves, massive bodies

Observations [O] vs. controlled physics experiments [E]

New non-null tests Shapiro time delay [O]

Geodetic effect by laser lunar ranging [O]

Binary pulsar, gravitational wave damping [O]

Gravity Probe A [E]

Gravity Probe B [E]

The Eddington PPN formalism & new null tests LLR, Nordtvedt effect restricts scalar-tensor theories [O]

Earth tides, Will effect eliminates Whitehead's theory [O]

GW astronomy [50 years since J. Weber detector]

GM/c2R << 1

Sun ~ 2 x 10-6 ; Earth ~ 7 x 10-10 ; 1 m W sphere ~ 5 x 10-21

Einstein 2½ Tests

The General Theory of Relativity:

Is THE Accepted Theory of Gravitation

Agrees to Better than 10-4 – 10-5 with Experimental Results

‹#›

Why Verify GR ?

General Relativity = Present Theory of Gravity

Mathematically Consistent

Agrees with Observation (so far)

Unified Physics ?

Standard Model: Quantum Gauge Theories

GR cannot be quantized

Partial steps toward Grand Unification

Strings/super symmetry

Damour - Polyakov

Experimentation and Observation

Gravity

Strong Nuclear Force

Weak Nuclear Force

Electro Magnetism

‹#›

Problems With GR ?

Astronomical Observations

A Dark Universe

An Expanding Universe

“Interesting” Phenomena

Solar System Observations ?

Pioneer Anomaly

Fly-by Anomaly

Short Scale Deviations ?

NGC 6251

Power 1038 W (1012 Suns)

Jet aligned 107 light years

GP-B science

Expansion of the

Universe Over Time

?

‹#›

How To Test Gravity ?

Astronomical Observations

CMB Polarization: WMAP, BOOMERANG

X Ray Polarization: GEMS

Pulsar Timing

Space Experiments

Gravitational Waves: LISA, DECIGO, BBO

Rotational Effects: GP-B

Space-Time Isotropy: STAR, OPTIS

Equivalence Principle: MICROSCOPE, STEP

Laboratory

Short Scale Deviations

Gravitational Waves: LIGO, VIRGO, Antennas

High Frequency GW

Gravity and Extreme

Magnetism (GEMS)

Boomerang

WMAP

Drag-free

Test Mass

High-Finesse ULE

Cavity Resonators AGIS Atomic Gravitational

Wave Interferometric Sensor

‹#›

Why Go To Space?

Seismic Noise @ f < 10Hz

Low gravity

Varying gravitational potential

Long baselines

“Fast” varying velocity vector 7 km/a @ 1.5 h vs. 0.4 km/s at 24 h

Long measurement times

Launch environment

Thermal environment

Cost and duration

Reliability; one shot

Communications bandwidth

‹#›

Drag-Free Technology

GP-B Flight Gyroscope 2004

TRIAD Sensor 1972

Control Spacecraft to follow an inertial sensor

Reduce disturbances in measurement band

Aerodynamic drag

Magnetic torques

Gravity Gradient torques

Radiation Pressure

‹#›

Why Test Gravity?

How To Test Gravity ?

Why Space ?

General Relativity, GP-B

‹#›

The Relativity Mission Concept

Geodetic Effect Space-time curvature

de Sitter (1916)

ee R

R

R

Rc

GIR

Rc

GM

232

1

32

3

241

2

1v

Controlled experiment

Frame Dragging Rotating matter drags space-time

Pugh and Schiff (1959, 1960)

"No mission could be simpler than Gravity Probe B.

… just a star, a telescope, and a spinning sphere." — William Fairbank

PPN Parameters

= 1 in GR

curvature of space

1 = 0 in GR

preferred frame effect

‹#›

Basis for 106 advance in gyro performance

Space

reduced support force, "drag-free"

roll about line of sight to star

Cryogenics

magnetic readout & shielding

thermal & mechanical stability

ultra-high vacuum technology

The GP-B Challenge

Gyroscope (G) 106 better than best 'modeled' inertial navigation gyros

Telescope (T) 103 better than best prior star trackers

Gyro Readout calibrated to parts in 105

G – T <1 marc-s subtraction within pointing range

‹#›

Main Experimental Features

Electrostatically suspended quartz gyroscopes with He spin-up

< 0.3 marcsec/yr drift

Telescope with cryogenic photo detector read-out pointed

<0.1 marcsec measurement, < 34 marcsec/Hz pointing

Drag free satellite in 642 km polar orbit, rolling at 5 mHz

<10-10 g, <10-12 g transverse

Cryogenic experiment 2K superfluid helium

>18 month lifetime

London moment based read-out with dc SQUID amplifiers

<200 marcs/Hz, <810-29 J/Hz

Superconducting magnetic shielding

< 510-7 G, >1012 total ac attenuation

All (almost) requirements met

‹#›

The GP-B Science Instrument

Mounting

flange

Quartz

block

Guide star

IM Pegasi

1 2

3 4

Gyros 3 & 4

Gyros 1 & 2 Star

tracking

telescope

Field of View: ±60 arc-sec.

Meas. noise: ~ 34 marcs/√Hz

SQUID Magnetometer (1 of 4)

Measurement noise: ~ 200 marcs/√Hz

SIA

‹#›

GP-B Systems

Probe Test of probe in dewar

Thermovac test of spacecraft

‹#›

GP-B Launch April 20, 2004

‹#›

The GP-B Gyroscopes

Fused quartz rotor R/R < 10-6

Quartz housing R/R < 10-5

Electrostatic suspension 10-9 g to 1 g

Capacitive positioning <0.3 nm at roll

He gas spin-up 60 - 80 Hz

UV charge control <15 pC

Electrical Suspension

He Gas Spin-up

Magnetic Readout

Cryogenic Operation

‹#›

A. Initial Orbit Checkout - 128 days

Re-verification of all ground calibrations [scale factors, tempco’s etc.]

Disturbance measurements on gyros at low spin speed

B. Science Phase - 353 days

Exploiting the built-in checks [Nature's helpful variations]

C. Post-experiment tests - 46 days

Refined calibrations through deliberate enhancement of

disturbances, etc. […learning the lesson from Harrison & Cavendish]

GP-B Science Mission 3 Phases

Anomaly 1 (Phase A, B) – Polhode-rate variations affect Cg determinations

Anomaly 2 (Phase B, C) – Larger than expected misalignment torques

Detailed calibration & data consistency checks eliminated many

potential error sources & confirmed many pre-launch predictions, but…

‹#›

A. Polhode period variations affect

scale factor (Cg) determinations

Observed in early science phase

B. Misalignment torques: req. 103

Observed in post-science calibration

C. Roll-polhode resonance torques

Observed in data analysis phase

3 Data Analysis Issues

All due to one physical cause:

The Patch Effect

Gyro 2 per orbit orientation

142 139 140 141 145 144 143 138 146

sEW

res. m

EW

orie

nta

tio

n,

s EW (

arc

se

c)

Date (2005)

0 0.2 0.4 0.6 0.8 10

0.5

1

1.5

2

2.5

3

3.5

4

Angle of Misalignment (degrees)

Dri

ft R

ate

(as/d

ay)

Magnitude of Drift Rate vs. Angle of Misalignment

Gyro 1

Gyro 2

Gyro 3

Gyro 4

140 190 240 290 340 390 440

4

3

2

1

Gyro 1 Polhode Period

Time (days from Day #1; Apr. 20, 2004)

H

ou

rs

‹#›

RESONANCE Repeat events

to 200 marcs

LINEAR DRIFTS Apparent linear drift

about 500 marcs/yr

MISALIGNMENT

Roll averaged

1,000 to 2,500 marcs/yr

GP-B Performance

DESIGN

100

10

1

0.1

0.01

1000

marc

sec

/yr

6,606 Geodetic effect

39.0 Frame dragging

effect

0.50 GP-B

Requirement

‹#›

Relativity

Misalignment

torque Roll-polhode

resonance torque

Add misalignment torque term to equations of motion

Add roll-polhode resonance term to equations of motion

Relativity & Newtonian

Torque Model

‹#›

Effects of Patch Potentials

Observations explained by patch effect of

~50 - 100 mV on rotor and housing

8 Observed Effects

1. Coupling to GSS

Z axis force

2. At zero frequency

3. At polhode harmonics

Torques

4. Misalignment

5. Resonance

Dissipation mechanisms

6. Polhode damping

7. Spin-down

8. Charge meas. bias

Affects read-out performance

Affect gyro performance

‹#›

Raw Flight Data (Gyro 2)

Apply Torque Model

‹#›

Newtonian Effects

Removed

Jan 8 Jan 28 Feb 17 Mar 9 Mar 29 Apr 18 May 8

Jan 8 Jan 28 Feb 17 Mar 9 Mar 29 Apr 18 May 8

date (2004)

–0.5

0.0

0.5

1.0

1.5

2.0

1.64

1.66

1.68

1.70

1.72

1.74

EW

orien

tation (

arc

sec)

NS

orienta

tion (

arc

sec)

EW uniform drift

NS uniform drift

Gyro 2, orientations – Newtonian torques

–1

+1

‹#›

Gyro 1 Segments

Consistency

NS / EW observability varies due to annual aberration

Seg. 2-3

Seg. 9

Seg. 5-6

Seg. 10

95% confidence ellipses

Seg. 5,6,9,10

‹#›

Four-Gyroscope

Consistency

Gyro 2

Gyro 4

Gyro 3

Gyro 1

Gyros

1,2,3,4

95% confidence ellipses

‹#›

1 marcsec/yr = 3.2×10-11 deg/hr = 1.510-16 rad/sec

Gyroscope Performance

ma

rcs

ec

/yr

105

106

107

108

109

1010 Electrostatic gyro

uncompensated

(10-1 deg/hr)

Electrostatic gyro

with modeling

(10-5 deg/hr)

Spacecraft gyros

(3x10-3 deg/hr)

Laser gyro

(10-3 deg/hr) Expected GP-B

104 -105 improvement over previous gyroscopes

39 Frame dragging effect

6,606 Geodetic effect

~ 1,000 Patch effects

GP-B Gyro Design m

arc

se

c/y

r

103

102

10

1

10-1

104

10-6

10-6

‹#›

GP-B Summary

GP-B worked very well

All systems performed beyond expectations

Anomalous effects

Explained by patches on rotor and housing

Systematic errors ~ 10 marcs

Complex experiments in space work

Surprises can be overcome: patch modeling

‹#›

Why Test Gravity?

How To Test Gravity ?

Why Space ?

General Relativity, GP-B

Lorentz Invariance, STAR

‹#›

Gravitational Science

on Small Satellites

GOALS

Gravitational experiments (+others?)

Lorentz invariance

Fundamental constants in variable potential

Small satellite missions

180 kg, 150W

60 M$, < 6 years

Education

PhD thesis, undergraduates

Capability continuity

IMPLEMENTATION

STAR program

3-5 projects

Start 2009, first launch 2015

‹#›

Why Measure c Invariance?

Colladay and Kostelecky (1997)

“The natural scale for a fundamental theory including gravity is

governed by the Planck mass MP, which is about 17 orders of

magnitude greater than the electroweak scale mW associated

with the standard model. This suggests that observable

experimental signals from a fundamental theory might be

expected to be suppressed by some power of the ratio:

r ≈ mW ∕ MP ~ 10−17

STAR’s one part in 1017 sensitivity

could close that gap.

STAR = Space-Time Asymmetry Research

‹#›

Kennedy-Thorndike

100 gain over the best KT measurement

R.J. Kennedy E.M. Thorndike

History of KT resolution

KT STAR Mission Objectives

Measure the boost anisotropy of the velocity of light to 10-17

Derive KT coefficient to the corresponding resolution, ~ 7x10-19

Readout Description

Orbital velocity varies with respect to CMB.

If c depends on vS relative to CMB, the

resonant frequency of the cavities changes.

Signal at orbital period TKT (TKT ≈ 100 min)

STAR compares the frequency of cavity to

wavelength of molecular-iodine stabilized

laser as absolute frequency reference.

‹#›

Lorentz Invariance

Targeted Outcomes for Astrophysics

1. “Test the validity of Einstein’s General Theory of Relativity;”

2. “Investigate the nature of space-time through tests of fundamental

symmetries; (e.g., is the speed of light truly a constant?)”

NASA Science Plan 2007-2016

Lorentz contraction parameter

time dilation parameter

tests for transverse contraction

GR: c() /c = 1, KT = MM = 0

CMB: preferred frame (vCMB /c)2 = 10-6

1. Test space/time symmetry

2. Improve understanding of cosmological parameters in

Standard Model Extension (SME)

2

22

2

2

2111ccc

c

sin)(

),( vvv

KT MM

‹#›

Component of SME Beat Signal

‹#›

Main Systems

Commercially available

components reduce risk

and keep STAR low-cost

Iodine Gas Cell Absolute

Frequency Reference

1064 nm Nd:YAG Laser

Frequency Shifters

Multi-Layer Thermal Shield for Sub-µK

Thermal Stability of Enclosure High-Finesse ULE

Cavity Resonators

‹#›

Major Mission Characteristics

Measure the anisotropy of the velocity of light to 10-17

Primary data product: map of local values of c

Orbit: most precessing sun-synchronous LEO’s

Launch vehicle: Secondary payload

Altitude: 650 km

Mission duration: One year

Launch: late 2015

Cost: $ 50M

Spacecraft in orbit concept

165 kg

110 W

Lasers/Optics Deck

Electronics

Cavities &

Core Optics

Spacecraft structure

Payload layout

LISA technologies

Iodine clocks

Optical cavities

Thermal enclosure

Frequency doublers

‹#›

Why Test Gravity?

How To Test Gravity ?

Why Space ?

General Relativity, GP-B

Lorentz Invariance, STAR

Gravitational Waves, LISA

‹#›

Gravitational Waves (GW)

In the weak field approximation GW can be represented

as a perturbation to the Minkowski flat space-time:

g Minkowski space perturbed by gravitational waves

Minkowski space

h gravitational waves perturbation hg

Using the transverse traceless gauge the field equation for h is:

S Energy densities and stresses

2 1

c2

2

2t 2

h

G

c4S

In GR h results in two plane waves with polarizations at 45°:

h a ˆ h t z

c

b ˆ h t

z

c

‹#›

Gravitational Radiation: The Quadrupole

Space is “stiff” (2G/c4 = 1.710-44 s2kg-1m-1)

The GW perturbation h propagates as 1/r

The quadrupole is the first gravitational radiation moment

The leading gravitational radiation term is

h Minkowski space perturbation

G gravitational constant

r distance to the source

Q trace-free quadrupole tensor

..124

Qrc

Gh

‹#›

LISA Concept

Three spacecraft in triangular formation separated by 5 million km

Spacecraft have constant solar illumination

Formation trails Earth by 20°

Orbit position and velocity modulate GW amplitude and phase

From amplitude and phase LISA determines direction to source to <1°

‹#›

The LISA Gravitational-Wave Sky

‹#›

Gravitational Waves Through Time

‹#›

The GW Spectrum

Bar Detectors

HF EM Detectors

BBO

DECIGO

‹#›

The Earth Based GW Detectors

GW Detection by 2015-2020

‹#›

LISA Systems

Payload Spacecraft Propulsion

module Launch

configuration

Y tube Optical bench Test mass

‹#›

LISA Path Finder Development

GRS Housing Torsion balance

Optical components Optical bench

‹#›

Two Optical Benches in Spacecraft

‹#›

Space GW Missions

LISA

2025

Arms are 50,000 km

LISA II

20??

LPF

2013

‹#›

Conclusions

GR most likely needs updating

GP-B shows that complex experiments in space do work

GW space observatory should be functional next decade

STAR could see first LIV this decade

Space science can and will be done on ‘small’ missions

Gravitational experiments are “taking off” in the next decade

‹#›

Looking to the Future

The towering figure of Einstein

provides a tempting target for

physicists of all stripes.

He would perhaps look with

approval on these efforts to go

beyond his theories.

The Search for Relativity Violations

Alan Kostelecky

Scientific American 2004

‹#›

‹#›

GP-B Back-up

‹#›

Gravitoelectric and

Gravitomagnetic Viewpoint

Similarity between electromagnetism and

General Relativity in weak field and slow motion limit

Space-Time

Metric

Newtonian

Analog

EM

Analog

Gravito-EM

Analog

Rotational

Effect

g00 V Eg 1/3G

g0i No analog Ai Bg FD

gij No analog No analog No analog 2/3G

‹#›

“Near Zeros” Technologies

6

4

Seven Near Zeros for Gyro Performance

Rotor inhomogeneities < 10-6 met

Rotor asphericity < 10 nm met

"Drag-free" (cross track) < 10-11 g met

Magnetic field < 10-6 G met

Pressure < 10-12 torr met

Electric charge < 15 pC met

Electric dipole < 0.1 Vm issue 2

1

3

5

‹#›

Rotor Fabrication

Profile of

Optical Path Difference - nm

Holder for Quartz

Homogeneity Measurement

Polishing System

Roundness

Measurement

Surface Profile Scaled to Earth Size

Radius 1.9 cm

Homogeneity < 2 ppm

Sphericity < 1 ppm

Mass unbalance < 1 ppm

I/I < 310-6

Nb Film Uniformity <2%

Met All

Requirements

Surface Profile

Min=9 nm |Max-Min|=19 nm Max=10 nm

‹#›

Housing Fabrication

Radius 1.9 cm

Sphericity < 10 ppm

6 Electrodes in 3 Orthogonal Pairs

5 Turn Read-out Loop

Channel and Ti Nozzle for Spin-up

7-layer Ti-Cu Electrode Coating

3-layer Ti-Cu-Ti Support and

Spin-up Lands Coatings

Ti Film For Bare Quartz

Three Layer Film Seven Layer Film SEM Micrograph SEM Micrograph

Gyro to Spacer Assembly

Spin-up Half Read-out Half

Fused-Quartz Gyroscope Housing

Gyro insertion in Quartz Block

Lands Coatings

Electrodes Coatings

Met All

Requirements

‹#›

Spin-up and Alignment

0 0.5 1 1.50

10

20

30

40

50

60

70

80

90

100

Time (hours)

Spin

rate

(H

z)

Gyro 1

Gyro 2

Gyro 3

Gyro 4

Spin-up of one gyro causes spin

down of other ones: Gyro 1 last

4 Gyroscopes spun to 60-80 Hz

Differential Pumping Requirement

Spin channel ~ 10 torr (sonic velocity)

Electrode area < 10-3 torr

Torque Switching Requirement

Ts, Tr - spin & residual torques

ts - spin time; Ω0 - drift requirement

Tr / Ts < Ω0ts ~ 10-14

First Science Mission Levitation

Gyro #

f (Hz)

df/dt (μHz/hr)

1 79.4 0.57

2 61.8 0.52

3 82.1 1.30

4 64.8 0.28

-250 -200 -150 -100 -50 0 50 100 150 200 250-250

-200

-150

-100

-50

0

50

100

150

200

250

W - E (arc-sec)S

- N

(arc

-sec)

saa-summary-plot.m <GSV median> Contour interval = 25 arc-sec

Gyro1

Gyro2

Gyro3

Gyro4

Spin Alignment to 10 arcsec

Spin speed and spin down meet requirements

‹#›

GP-B on Jon Stewart’s Daily Show

‹#›

GP-B in Flight

GOOD Gyroscopes

104-105 better than ground

SQUID noise meets spec

Trapped magnetic flux meets spec

Charge control ~ meets spec

Position and stability meet spec

τ ~ 7200 to 26000 yr meet spec

Telescope

Meets spec

Dewar

20 months hold meets spec

Orbit within 100 m of ideal

LESS THAN IDEAL Torques

Misalignment torque

Resonance torque

Other

Polhode rate variation

Segmented data

Interference from ECU

SRE scale factor

Systematics &

data grading

New Challenge

‹#›

N-S (Geodetic) E-W (Frame-dragging)

G1

G2

G3

G4

Full Model Results (Dec ’08)

(note: different y-axis scale for N-S vs. E-W)

‹#›

STAR Back-up

‹#›

Michelson Morley Secondary

COSMIC MICROWAVE BACKGROUND

MM STAR Mission Objectives

Measure the anisotropy of c to 10-17

Derive the MM coefficient to ~ 10-11

Derive the generalized coefficients of LIV

• boost independent: < 7x10-17

• boost dependent: ~ 10-13

Readout Description

Compare the resonant frequencies of two

orthogonal high-finesse optical cavities

Signal at 1/2TMM (TMM = 2 – 20 min)

Configuration conceptually similar to MM

History of MM resolution

‹#›

LISA Back-up

‹#›

Gravitational and

Electromagnetic Waves

Gravitational Electromagnetic

Source Coherent mass acceleration

Incoherent charge acceleration

Propagation Space-time oscillations

(2 polarizations at 45°)

EM fields in space-time

(2 polarizations at 90°)

Attenuation None Scattering, absorption

Frequency <10 kHz (possibly higher) >10MHz (radio to gamma)

‹#›

The DECIGO Project

Japanese Space Agency

10-18

10-24

10-22

10-20

10-4 104 102 100 10-2

Frequency [Hz]

Str

ain

[H

z-1/2

] LISA

Terrestrial Detectors

(e.g. LCGT) DECIGO

(Sensitivity: Arbitrary)

‹#›

Advanced Concepts - Stanford

Single spherical proof mass (PM) per S/C

LPF (LISA Pathfinder): 2 cubic ones

Non constraint GRS; 0 of 6 DF (deg. freedom) control

LPF: 9 of 12 DF control

Gravitational sensor separation from S/C Interferometry

LPF: implemented

Fiber utilization

LPF: discrete optics

Reflective optics d/dl 0.1 d/dn

LPF: transmissive optics d/dn10 d/dl

Signal

LO

GRS with double

sided grating for

interferometer and

PM reference

‹#›

Bench Interferometer Configuration

(Example: Polarization Sensitive Grating Beam Splitter)

Proof Mass

Highly simplified

structure compared with

transmissive optics

Laser

Out to

Telescope

In from

Telescope

Detector

Grating

(Other diffraction orders with

detectors not drawn for simplicity)

‹#›

Grating Cavity Displacement Sensing

Sensitivity better than 10 pm/Hz

Goals for Sensor High precision: 1 pm / Hz in LISA band Low power: Less than 20 W optical power Compact: Fiber delivery and read-out

Preliminary Results: 10 pm/ Hz f > 3 kHz

Low-Finesse Littrow Cavities as Displacement Sensors

K.-X. Sun, G. Allen, S. Buchman, D. DeBra, and R. Byer,

Classical and Quantum Gravity 22, S287–S296 (2005)

Patent pending

‹#› Ke-Xun Sun, Sasha Buchman, Robert L. Byer, “Grating Angle

Magnification Enhanced Angular and Integrated Sensors for LISA

Applications,” Journal of Physics CS, 32:167-179, 2006.

Grating Angular Sensor

for Space Missions

Simple construction

No extra optics

No other uncertainty and noise

Experimental Setup

Patent pending

‹#›

Optical Position Determination:

Simulation Spinning sphere, 10 Hz

2 Dimensional

6 Optical sensors

Experimental laser noise

50 nm position noise

50 nm surface roughness

1024 map size

fnoise/fspin = 10-6 3 pm/Hz position noise

‹#›

Utilizing Launch Margins

Technology Demonstrations for the

Gravitational Reference Sensor - GRS

MINISAT, The Mini Satellites

for GRS Technologies

The Program

Frequent launches on ride-along platforms

Standard low cost bus configurations

12 - 24 month project duration

The Benefits

New science: Physical, Life, Engineering

Critical technology demonstrations

Fast advance of NASA mission objectives

Train engineers and scientists for the future

Program Implementation

Collaboration: AMES, Stanford University

Continuity: 1 to 2 missions per year

Total cost per mission: 5 million dollars

AMES

GENESAT

Stanford

NANOSAT

UV LED