IA contributes to the technology for the detection of gravitational waves
2016 November 28
Configuration of the LISA optical bench. Credits: AEI/MM/exozetAn international consortium, of which the Instituto de Astrofísica e Ciências do Espaço (
IA1) is a member, is defining and producing the prototype of the high power laser heads that will be incorporated into each of the three spaceships of the mission
LISA2, of
ESA. The work of IA's team is to develop a software simulation to assess the best strategies to stabilise the frequency and intensity of the laser beam over time and within the limits required by ESA.
The stabilisation level of the laser beams is critical to the LISA mission due to the fact that the spaceships are separated by two million kilometres and due to the high accuracy required for the measurement of this distance. The laser beam emitted by one of the spaceships reaches the other so weakened that it is impossible to reflect it back. The solution is to send a replica of the received beam by means of a second laser and in tune with the first, which demands a very high stabilisation level.
Manuel Abreu (IA and
Faculdade de Ciências da Universidade de Lisboa), coordinator of IA's participation in the consortium, says: “Due to the nature of the specific gravitational waves to be detected, and which period is several hours, the stabilisation level required would be that of ensuring that the temperature of the room where we are must be stabilised to the thousandth of a degree Celsius during a whole day and that it cannot change. Ensuring that it is stable to that extent is very, very difficult.”
The team at IA simulated the whole optical process of ensuring the stabilisation and which will be implemented in terms of electronics by
LusoSpace, the Portuguese company leader of the consortium. With the acceptance of the preliminary design by ESA, it was demonstrated that the proposed technological solution is viable and that the consortium can move on to the detailed design.
The participation of IA in this consortium is strategic to the development of new technology, but also for the future science that IA will be able to produce with the data collected by LISA. “The more visibility we can get in the domain of LISA, the more we can be part of future work linked to this observatory, which will obviously be fascinating,” says Manuel Abreu.
This work at IA was conducted at Laboratório de Óptica, Lasers e Sistemas (Laboratory of Optics, Lasers and Systems,
LOLS), a technology transfer unit of Faculdade de Ciências da Universidade de Lisboa. The team is composed of
Manuel Abreu, João David Mateus,
David Castro Alves and
Alexandre Cabral.
NOTES
- The Instituto de Astrofísica e Ciências do Espaço (Institute of Astrophysics and Space Sciences – IA) is the largest Portuguese research unit in space sciences and integrates researchers from the University of Lisbon and the University of Porto. The institute encompasses most of the field’s national scientific output and it was evaluated as Excellent in the last evaluation from the European Science Foundation (ESF). IA’s activity is funded by national and international funds, including Fundação para a Ciência e a Tecnologia (UID/FIS/04434/2013), POPH/FSE and FEDER through COMPETE 2020.
- LISA will be a space observatory with the purpose of detecting gravitational waves, periodical contractions and expansions in the curvature of space-time generated by the movement of massive bodies. These waves produce changes in the distance between two objects, for instance, two spaceships. The measurement of gravitational waves provides direct information about the movements of the massive bodies that started them, such as black holes. The LISA concept is based on the measurement of phase differences between two laser beams emitted and received by three spaceships forming an equilateral triangle which sides measure two million kilometres.
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Configuration of the LISA optical bench. Credits: AEI/MM/exozet
