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The Kepler Mission depends on the ability
to reliably measure the very small relative change in brightness
of a star caused by the transit of an Earth-size planet. We have
constructed a high-fidelity Testbed Facility of the end-to-end
photometry system. This has been used to show that under all
of the expected operating conditions which can add noise to the
measurements, the signature of an Earth-size transit is readily
detectable.
This page provides an overview of the the
technology demonstration that has been performed. It is followed
by a page on the laboratory facility that has been constructed
and then by a page that discusses the results.
Overview
To perform an end-to-end system test of the Kepler Mission a laboratory facility has been built to
replicate the elements that will compose the flight system. The laboratory system consists of:
- A simulated star field that represents all of the features of the real sky that are important for ensemble photometry;
- A photometer that operates and has the same characteristics of the flight photometer, including:
- Fast optics to focus the star field onto the CCD detector,
- A commercially available CCD that could be used in the flight system,
- High speed readout electronics (operating at 1 mega pixel/sec/amp) to process the data as if onboard the spacecraft, and
- Ground software used to produce the light curves, detect transits and evaluate the precision of the data.
- A structure that provides thermal, mechanical and RF isolation and stability from the laboratory environment.
The objective of the technical demonstration
was to show that this end-to-end system can maintain the required
relative precision over a period of time necessary to detect
transits when all of the confounding noise factors are included.
Note that the critical parameter is only relative precision,
that is, the ratio of the flux of one star relative to the fluxes
of many nearby stars read at the same time on the same CCD.
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