The Laser Interferometer જગ્યા Antenna (LISA) mission has received the go ahead of European જગ્યા Agency (ESA). This paves the way for developing the instruments and spacecrafts commencing January 2025. The mission is led by ESA and is a result of collaboration between ESA, its Member State જગ્યા agencies, નાસા, and an international consortium of scientists.
Scheduled to be launched in 2035, LISA will be the first જગ્યા-આધારિત ગુરુત્વાકર્ષણ તરંગ observatory dedicated to detection and study of millihertz ripples caused by distortions in the fabric of જગ્યા-time (ગુરુત્વાકર્ષણ તરંગો) સમગ્ર બ્રહ્માંડ.
Unlike the ground based ગુરુત્વાકર્ષણ તરંગ detectors (LIGO, VIRGO, KAGRA, and LIGO India) which detect ગુરુત્વાકર્ષણ તરંગો in frequency range of 10 Hz to 1000 Hz, LISA will be designed to detect ગુરુત્વાકર્ષણ તરંગો of much longer wavelengths in the low frequency range between 0.1 mHz and 1 Hz.
અલ્ટ્રા-લો-ફ્રિકવન્સી (10-9-10-8 હર્ટ્ઝ) ગુરુત્વાકર્ષણ તરંગો (GWs) with wavelengths from weeks to years from supermassive binary કાળા છિદ્રો can be detected using ground-based પલ્સર ટાઇમિંગ એરે (PTAs). However, low frequency ગુરુત્વાકર્ષણ તરંગો (GWs) with frequency between 0.1 mHz and 1 Hz can neither be detected by LIGO nor by Pulsar Timing Arrays (PTAs) – the wavelength of these GWs is too long for LIGO and too short for PTAs to detect. Hence, the need for જગ્યા-based GW detector.
LISA will be a constellation of three spacecrafts in accurate equilateral triangle formation in space. Each side of the triangle will be 2.5 million km long. This formation (of the three spacecrafts) will ભ્રમણકક્ષા Sun in an Earth-trailing heliocentric ભ્રમણકક્ષા between 50 and 65 million km from Earth while maintaining a mean inter-spacecraft separation distance of 2.5 million km. This space-based configuration makes LISA an extremely large detector to study low frequency ગુરુત્વાકર્ષણ તરંગો that ground-based detectors can not.
For detection of GWs, LISA will use pairs of test masses (solid gold-platinum cubes) free-floating in special chambers at the heart of each spacecraft. ગુરુત્વાકર્ષણ ripples will make extremely small changes in the distances between test masses in the spacecrafts which will be measured through laser interferometry. As demonstrated by LISA Pathfinder mission, this technology is capable of measuring changes in distances to a few billionths of a millimetre.
LISA will detect GWs caused by merger of supermassive કાળા છિદ્રો at the centre of galaxies thus will shed light on evolution of galaxies. The mission should also detect the predicted gravitational 'રિંગિંગ' formed in the initial moments of the બ્રહ્માંડ in the first seconds after the big bang.
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સંદર્ભ:
- ESA. સમાચાર -અવકાશ સમયની લહેરોને પકડવી: LISA આગળ વધશે. 25 જાન્યુઆરી 2024 ના રોજ પોસ્ટ કરવામાં આવ્યું. પર ઉપલબ્ધ https://www.esa.int/Science_Exploration/Space_Science/Capturing_the_ripples_of_spacetime_LISA_gets_go-ahead
- નાસા. લિસા. પર ઉપલબ્ધ છે https://lisa.nasa.gov/
- Pau Amaro-Seoane et al. 2017. Laser Interferometer જગ્યા Antenna. Preprint arXiv. DOI: https://doi.org/10.48550/arXiv.1702.00786
- Baker et al. 2019. The Laser Interferometer જગ્યા Antenna: Unveiling the Millihertz Gravitational Wave Sky. Preprint arXiv. DOI: https://doi.org/10.48550/arXiv.1907.06482
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