PSSL, Precision Space Systems Laboratory University of Florida Florida Space Summit 2026

Discovery Session #1 · Exploration Cislunar to Distant Universe

From Gainesville to Deep Space

Florida’s Role in LISA, the International Gravitational Wave Observatory

Simon BarkePrecision Space Systems Laboratory, University of Florida

Talk #102Kennedy Space Center, Center for Space EducationOctober 20, 2026

Animation: UF / S. Barke (CC BY 4.0)

Gravitational waves

Listening to a universe in motion

Listening, not watching

Our goal: to listen to the universe. Gravitational waves are more like sound than light: detectors hear the whole sky at once and record the wave itself, not a picture.

Ripples in spacetime

Mass curves spacetime. When masses accelerate, that curvature ripples outward at the speed of light, stretching and squeezing the distances between objects.

Everything moves

Planets circle stars, stars orbit each other, collapse and merge, galaxies collide: the universe is always in motion, and full of gravitational waves.

Cartoon: a blue vampire star with bat wings drinks plasma from a crying orange star

Cosmic Bloodlines

Vampire Stars

When stars feed on each other, spacetime ripples

A VLTI/PIONIER image of SS Leporis, 28 October 2010 VLTI/PIONIER images of SS Leporis, 7 and 22 December 2010
The Enterprise passing a binary star: a red giant streaming onto a blue companion (Star Trek: The Next Generation, “Evolution”)
1989/09/25Star Trek: The Next Generation, “Evolution”

SS Leporis · 910 light-years from Earth · VLTI/PIONIER · 2010 · 55 days OBSERVATION

Orbit260 days
Separation1.26 AU
Red GiantMass: 1.3 M☉ (Ø 0.62 AU)
CompanionMass: 2.7 M☉ (accretion disk)

Images: ESO/PIONIER/IPAG · Star Trek: The Next Generation, “Evolution” (season 3, episode 1), first aired 25 September 1989 © CBS Studios/Paramount

One gravitational wave source

Interacting binaries

  • A hot, heavy star
    captures matter from a red giant
  • The red giant
    becomes lighter and larger in diameter
  • Accelerated motion
    creates ripples in spacetime,
    known as gravitational waves
  • Here on Earth
    they stretch and squeeze distances
    by about 1 part in 10²³, every 130 days

Animation: UF / S. Barke (CC BY 4.0) · Image: ESO/PIONIER/IPAG · Data: Blind et al. 2011 · Orbit to scale, waves exaggerated

Heavier vampires · what comes next

From vampire to black hole

Close binary: a still from the animation

Close binary

The vampire pulls a stream of plasma off its swollen partner; one orbit takes months (SS Leporis: 260 days).

≈ 0.1 µHzfar too faint to detect

Common envelope: a still from the animation

Common envelope

A supernova leaves a pulsar; the swelling giant engulfs it, and drag shrinks their orbit from days to hours.

0.02 – 0.2 mHztoo faint to detect

Ultra-compact binary: a still from the animation

Ultra-compact binary

The envelope is gone: two compact remnants circle each other in minutes, for up to millions of years.

0.5 – 50 mHzLISA

Merger & ringdown: a still from the animation

Merger & ringdown

In the final seconds the signal rises in pitch and loudness; then the new black hole rings like a struck bell.

10 Hz – 3 kHzLIGO · Virgo · KAGRA

Stills from the animation: UF / S. Barke (CC BY 4.0) · Gravitational-wave frequencies, typical ranges · Signals sketched

Gravitational wave detectors

Different waves, different detectors

  • Like light: an X-ray telescope can’t see infrared
  • On the ground: LIGO, Virgo and KAGRA, with arms 3 to 4 km long
  • They hear 10 Hz to a few kHz: the last seconds of merging black holes and neutron stars

Animation: UF / S. Barke (CC BY 4.0) · Earth: NASA Blue Marble, Black Marble

Gravitational wave detectors

LISA: a detector in space

  • For scale: the Moon, 384,400 km from Earth
  • Three spacecraft, 2.5 million km apart
  • It hears 0.1 mHz to 1 Hz, far below what ground detectors can

Animation: UF / S. Barke (CC BY 4.0) · Earth: NASA Blue Marble, Black Marble · Moon: NASA LRO

What is LISA?

A gravitational wave observatory in space

2.5 M kmarms: laser links between three spacecraft, both ways
6test masses in free fall, two in each spacecraft
mHz0.1 mHz – 1 Hz, out of reach for ground detectors
2035planned launch, ESA‑led with NASA; 4.5 years of science

Animation: UF / S. Barke (CC BY 4.0) · Orbit to scale, the camera following the constellation · Laser beams drawn visible

LISA technology

Who builds what

ESA · with its member states

LISA Pathfinder’s inertial sensor head in its vacuum chamber

Gravitational reference sensor

The free-falling test mass in its housing

Italy, with Switzerland

Glass optics bonded to an optical bench (LISA Pathfinder)

Optical bench

Splits, combines and senses the laser beams

United Kingdom

A module of LISA’s phasemeter under test at the AEI Hannover

Phasemeter

Tracks the beat notes’ phase, the actual measurement

Germany, with Denmark

NASA

The gold-coated LISA telescope engineering unit

Telescope

Sends and receives the beams across 2.5 million km

NASA Goddard · L3Harris

The LISA prototype laser after thermal vacuum tests at NASA Goddard

Laser

Ultra-stable infrared light, 1064 nm

NASA Goddard

The prototype LISA charge management device, built by UF and Fibertek

Charge management device

UV light keeps the test masses electrically neutral

UF · PSSL with Fibertek, for NASA

Photos: NASA/Dennis Henry (telescope, CMD) · NASA/Sophia Roberts (laser) · CGS SpA (GRS) · University of Glasgow (optical bench) · © MPI for Gravitational Physics (phasemeter) · GRS and bench: LISA Pathfinder’s

Gravitational reference sensor

A cube in a box

Test mass 46 mm gold–platinum cube, floating free in its housing Laser readout an interferometer tracks one axis to picometres Electrodes sense the other axes and nudge the cube with voltages e⁻e⁻ UV light frees electrons: removes the charge cosmic rays leave
A LISA Pathfinder test mass: a gold–platinum cube
The cube: a 46 mm gold–platinum test mass
Inside a LISA Pathfinder electrode housing, its gold-coated electrodes
The box: its electrode housing, from inside

Photos: ESA/CGS SpA (test mass, CC BY-SA 3.0 IGO) · CGS SpA (electrode housing) · both LISA Pathfinder flight hardware · Diagram: gaps exaggerated

Proven in space

LISA Pathfinder

LISA Pathfinder lifted onto its launch adapter in Kourou
The spacecraft, Kourou, November 2015
The flight model of the LISA Technology Package core assembly
The payload: a test mass housing at each end, the optical bench between
LISA Pathfinder's flight optical bench
The optical bench: silica optics bonded to a Zerodur plate
2015launched 3 December on Vega; flew around Sun–Earth L1 until July 2017
46 mmtwo gold–platinum test masses in free fall, 1.9 kg each
Sub‑femto‑gfree fall to 1.74 fm s⁻²/√Hz, beyond what LISA needs
254 nmUV from mercury lamps kept the masses neutral; LISA will use UV LEDs

Photos: ESA–Manuel Pedoussaut (spacecraft) · Airbus Defence and Space (payload) · Universities of Glasgow and Birmingham (optical bench)

Charge management device

UV light from Gainesville

  • UV LED unit: 250 nm light, from 10 pW to 500 nW
  • Fiber harness: carries it to both test masses on each spacecraft
  • TRL 6: vibration, EMI, thermal vacuum, radiation; the engineering unit is next

Rendering of the ULU engineering test unit from Fibertek’s CAD model · © Fibertek, Inc., University of Florida, Simon Barke

Charge management device · requirements

From 10 pW to 500 nW

RequirementValueWhy
High power500 nW DC; 125 nW pulsed (≤ 10 % duty)fast discharge
Low power10 pW, DC and pulsedcontinuous discharge, hardly any added charge noise
Pulsesup to 98,304 per second, in step with a 98,304 Hz clockthe dose: pulse count and duty cycle
Power stability< 0.1 /√Hz (pulsed < 2 nW, quasi‑DC < 125 pW)limit noise from charges coupling to electric fields
Phase stability< 7 mrad/√Hzthe same
Wavelengthpeak 247–259 nm, < 10 % outside its envelopephotons that free electrons from gold
Repeatabilitywithin 3 % over two weeksa predictable discharge

Rendering from Fibertek’s CAD model © Fibertek, Inc., University of Florida, Simon Barke · Requirements: F. Barbieri, UF, TRL 6 tests, 2026

Science goals · Why space

Listening to the millihertz universe

  • Massive black hole mergers across cosmic history
  • Thousands of compact binaries in our own galaxy
  • Extreme mass-ratio inspirals that map spacetime around black holes
  • Why space: Earth’s seismic noise drowns out millihertz signals, and the arms must be millions of km long

Animation: UF / S. Barke (CC BY 4.0)

What makes LISA work

Picometers over millions of kilometers

  • Free-falling test masses: gold–platinum cubes shielded by drag-free spacecraft
  • Heterodyne interferometry: MHz beat notes between lasers on separate spacecraft, tracked by phasemeters
  • Time-delay interferometry: a virtual Michelson interferometer assembled on the ground cancels laser frequency noise
  • Picometer sensitivity at millihertz frequencies [target noise figure]

NASA’s contribution

What the US is building for LISA

Lasers

Stable 1064 nm light sources for the inter-spacecraft links [power, lead center]

Telescopes

Send and receive the beams across 2.5 million km [aperture, lead center]

Charge Management Device

Keeps the test masses electrically neutral with UV light [UF-led, partners]

Made in Gainesville

UF’s role in LISA

Concluded

Telescope testing

[What was tested, key result, facility]

In progress

Charge Management Device flight hardware

[Scope: design, build, qualification, delivery]

Charge Management Device

Where the CMD stands today

Status

ULU: UV LED Unit

Generates the UV light that discharges the test masses [current milestone]

Status

FOH: Fiber Optic Harness

Guides the UV light to the test masses [current milestone]

[Next milestones and delivery schedule]

GRATTIS

Charge management in orbit, first

2027

The GRATTIS SACU carries the complete charge management system. Launch next year. [mission, platform, what it will demonstrate]

Don’t miss

More on LISA and GRATTIS

Talk #104 · 4:05 pm

Impact of Solar Energetic Particle Events on LISA Charge Management System Performance

Corey Richardson

Talk #163 · 4:35 pm

GRATTIS Payload Integration: Micrometer-Level Metrology on a Dual Inertial Sensor Assembly

Ethan Butz

Infrastructure Session #3: Space Systems, Sensing, & AutonomyRoom 7020

Thank you

Questions?

Simon BarkePrecision Space Systems Laboratorypssl.mae.ufl.edu

Animation: UF / S. Barke (CC BY 4.0)