Photograph · ESO / G. Vecchia
Technology

CELESTE Flight-Proven, tested,ready.

CELESTE utilizes flight-proven spacecraft and instruments in their intended environment.

System Architecture

A four-segment system.

The CELESTE architecture is intentionally compact. A space segment generates the guide star; a ground segment delivers the science. Optical communication links the two in real time.

A small laser in orbit.

The General Atomics laser guide star, mounted on a BCT Saturn smallsat bus. In low Earth orbit, ~700 km altitude.

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A reference star on the sky.

The laser projects an effective V ≈ 6 source visible to any equipped observatory. Beam divergence under 5 arcseconds.

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The giant telescope below.

The W. M. Keck Observatory — and, in time, ELT-class apertures. Existing adaptive-optics benches, untouched.

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The corrected image.

A visible-light coronagraph and broadband imager at the AO-corrected focus. Diffraction-limited resolution, sustained.

Inside the heart of the ELT.

The world's giant ground telescopes are nearly here. CELESTE gives them the visible-light eyes they would otherwise need a flagship space telescope to match.

Subsystems

Each part, in detail.

Every major CELESTE subsystem is built from flight-heritage or observatory-proven hardware. Below: the four major segments and their lead suppliers.

01 Space Segment

A flight-heritage BCT Saturn bus.

Blue Canyon Technologies provides power, thermal control, attitude determination, and data handling for the CELESTE payload.

  • Mass
    ~150 kg wet
  • Power
    350 W EOL
  • Pointing
    3 arcsec, 3σ
  • Orbit
    ~700 km SSO
02 Laser Guide Star

A General Atomics laser source.

A high-stability laser generates an artificial reference star visible to any equipped ground observatory. Heritage from GA's optical-payload program.

  • Wavelength
    589 nm (Na option)
  • Effective V-mag
    ~6 from ground
  • Beam divergence
    < 5 arcsec
  • TRL
    7
03 Ground Segment

Keck Observatory & LCRD.

CELESTE integrates with the existing AO infrastructure at Keck. NASA's LCRD provides the optical-communications link to and from the space segment.

  • Primary telescope
    Keck I & II (10 m)
  • Forward path
    ELT, TMT (planned)
  • Comm link
    LCRD-class · 1.55 μm
  • AO bench
    Existing Keck AO
04 Science Instrument

A visible-light coronagraph.

Coronagraph plus broadband imager mounted at the AO-corrected focus. Two modes: high-contrast imaging, and wide-field imaging.

  • Detectors
    EMCCD + CMOS
  • Filter wheel
    8 broad + 4 narrow
  • Coronagraph type
    Vector vortex, charge 4
  • Inner working angle
    2 λ/D
Comparison

CELESTE in context.

How CELESTE compares to current and planned facilities on the metrics that matter most for visible-light astrophysics.

Facility Wavelength Resolution at 0.5 μm Architecture Lifecycle cost
CELESTE 0.45 – 1.0 μm ~3 mas Hybrid space + ground Modest
Hubble 0.1 – 1.7 μm ~40 mas Space $$$$
JWST 0.6 – 28 μm ~70 mas* Space, infrared-optimized $$$$$
Roman 0.5 – 2.3 μm ~110 mas Space, wide-field $$$$
ELT 0.4 – 14 μm ~6 mas** Ground, near-IR AO $$$$
TMT 0.3 – 28 μm ~6 mas** Ground, near-IR AO $$$$

* At 1 μm — JWST diffraction limit at visible wavelengths exceeds these values.   ** At infrared wavelengths only; ground AO does not currently achieve the diffraction limit in visible light without a space-borne guide star.

Operations

A typical observation,
end-to-end.

Hybrid operations sequence the spacecraft and ground observatory for each science target. A single science pass takes between thirty minutes and several hours.

  1. 01.

    Target acquisition

    Ground telescope acquires science target. Spacecraft maneuvers to place the laser guide star within the field.

  2. 02.

    Beam on

    Spacecraft activates laser. LCRD link establishes telemetry. Beam is pointed within 2 arcseconds of target.

  3. 03.

    Adaptive-optics lock

    Ground AO bench detects guide star and closes the wavefront-correction loop at a 1 kHz update rate.

  4. 04.

    Science integration

    Coronagraph or imager integrates on target. Diffraction-limited resolution maintained continuously.

  5. 05.

    Handoff & reposition

    Spacecraft slews to next target. Telescope receives next pointing. Cycle repeats.