Atomic Clock Ensemble in Space (ACES) - 08.23.17

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Atomic clocks are currently used in various domains, from scientific research (time and frequency metrology, fundamental physics tests), to operational applications (positioning and navigation, GPS, GLONASS, geodesy, synchronisation of telecommunication networks). Atomic Clock Ensemble in Space (ACES) is an ESA mission in fundamental physics based on a new generation of clocks operated in the microgravity environment of the International Space Station. ACES can significantly contribute to the understanding of fundamental physics principles, and help advance technologies necessary for future operational systems using ultra stable space clocks, and high performance time and frequency links.
Science Results for Everyone
Information Pending

The following content was provided by C. Salomon, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.
Experiment Details

OpNom: ACES

Principal Investigator(s)
C. Salomon, ESA, France

Co-Investigator(s)/Collaborator(s)
M. Tobar, ESA, Austria
I. Procházka, ESA, Czech Republic
P. Laurent, ESA, France
A. Clairon, ESA, France
P. Wolf, ESA, France
M. Prevedelli, ESA, Italy
L. Lusanna, ESA, Italy
G. Tino, ESA, Italy
D. Piester, ESA, Germany
O. Montenbruck, ESA, Germany
W. Bosch, ESA, Germany
U. Schreiber, ESA, Germany
W. Ertmer, ESA, Germany
G. Beyerle, ESA, Germany
F. Riehle, ESA, Germany
S. Schiller, ESA, Germany
T. Sudmeyer, ESA, Switzerland

Developer(s)
European Space Agency (ESA), Noordwijk, Netherlands

Sponsoring Space Agency
European Space Agency (ESA)

Sponsoring Organization
European Space Agency

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration
March 2016 - September 2016

Expeditions Assigned
47/48

Previous Missions
Information Pending

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Experiment Description

Research Overview

The Atomic Clock Ensemble in Space (ACES) mission primary objectives are:
  1. To demonstrate the high performance of a new generation of atomic clocks in the space environment, and the ability to achieve high stability on space-to-ground time and frequency transfer.
  2. To demonstrate the capability to compare ground clocks at high resolution on a world-wide basis, using a link in the microwave domain (MWL).
  3. To perform fundamental physics tests.
ACES mission secondary objectives are:
  1. To characterize the long-term stability of the Space Hydrogen Maser (for integration times above 104 seconds).
  2. To demonstrate the feasibility of synchronizing ground clocks with a time uncertainty at the level of 100 picoseconds (ps).
  3. To provide the capability to improve the long-term stability and the accuracy of the International Atomic Time Scale.
  4. To demonstrate the capability to transmit to ground users an ultra-stable time scale with a time accuracy at the level of 100 ps.

Description
The Atomic Clock Ensemble in Space (ACES) payload involves state-of-the-art clocks and key subsystems. The heart of the overall mission is represented by two atomic clocks:  Projet d'Horloge Atomique par Refroidissement d'Atomes en Orbit (PHARAO), a primary frequency standard based on laser cooled cesium atoms, and Space Hydrogen Maser (SHM), an active hydrogen maser for space applications. PHARAO and SHM are compared onboard ACES in the Frequency Comparison and Distribution Package (FCDP).

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Applications

Space Applications
Information Pending

Earth Applications
The results from ACES hold significance with respect to the future of satellite navigation, for which the operation of clocks in space is essential. The combined performance of the ACES clock's signal will be 10 to 100 times more stable and accurate than the state-of-the-art technology on GPS and Galileo satellites. These studies will be extremely important for defining the best operating conditions of the primary frequency standard, and for the future development of atomic quantum sensors based on laser cooled atoms (optical clocks, atom interferometers, atom lasers) for use in space applications.

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Operations

Operational Requirements and Protocols
Information Pending

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites
Timely Arrival of Pharao Space Clock
Challenging Einstein on the ISS: ACES Takes a Step Ahead

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Imagery

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The ACES Payload and its attachment point on the Columbus Laboratory. Image courtesy of ESA.

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Schematic of ACES containing PHARAO and Space H-Maser. Image courtesy of ESA.

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