Atomic Clock Ensemble in Space
Encyclopedia
Atomic Clock Ensemble in Space is a project led by the European Space Agency
which will place an ultra-stable atomic clock
on the International Space Station. Operation in the microgravity environment of the ISS will provide a stable and accurate time base for different areas of research, including general relativity
and string theory
tests, time and frequency metrology
, and very long baseline interferometry
.
The payload actually contains two clocks: a caesium ion clock
for long-term stability and a hydrogen maser
for short-term stability.
The clock is planned to travel to the space station aboard a Japanese HTV
, and is to be externally mounted to the ESA's Columbus Laboratory
. The clock is planned to operate in orbit for 18–36 months.
Launch is planned in 2013 followed by a 12-18 month operations phase.
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
which will place an ultra-stable atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
on the International Space Station. Operation in the microgravity environment of the ISS will provide a stable and accurate time base for different areas of research, including general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
and string theory
String theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...
tests, time and frequency metrology
Metrology
Metrology is the science of measurement. Metrology includes all theoretical and practical aspects of measurement. The word comes from Greek μέτρον , "measure" + "λόγος" , amongst others meaning "speech, oration, discourse, quote, study, calculation, reason"...
, and very long baseline interferometry
Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
.
The payload actually contains two clocks: a caesium ion clock
Caesium standard
A caesium standard or caesium atomic clock is a primary frequency standard in which electronic transitions between the two hyperfine ground states of caesium-133 atoms are used to control the output frequency. They are one of the most accurate types of atomic clock...
for long-term stability and a hydrogen maser
Hydrogen maser
A Hydrogen maser, also known as hydrogen frequency standard, is a specific type of maser that uses the intrinsic properties of the hydrogen atom to serve as a precision frequency reference....
for short-term stability.
The clock is planned to travel to the space station aboard a Japanese HTV
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...
, and is to be externally mounted to the ESA's Columbus Laboratory
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....
. The clock is planned to operate in orbit for 18–36 months.
Launch is planned in 2013 followed by a 12-18 month operations phase.
External links
- ACES page at the ESA DEAD?
- ACES factsheet by the ESA (PDF) DEAD?