ESA will implement the eLISA mission in 2034

In 2034, the European Aeronautics Agency (ESA) will officially implement the eLISA mission. Accordingly, the set of three spacecraft will be launched into orbit and they will study gravitational waves that could one day extend our understanding of the universe.

>>>Video: ESA will implement the eLISA mission in 2034

The gravitational wave was first predicted by Albert Einstein's general theory of relativity nearly a century ago. Basically, gravitational waves are quite similar to sound waves but instead of being transmitted in air, gravitational waves ripple in the space / time structure. Although it has been predicted and searched for decades, no one has ever observed the gravitational waves. It is thought that gravitational waves are produced by all phenomena in the universe, such as the merger of black holes, giant stars and asteroids pushing each other and even cases. Big Bang explosion.

What makes the gravitational wave of interest to scientists is that unlike light, electronics or other forces, gravitational waves travel without interference. Dust, gas and light trails do not affect them, which means astronomers can use gravitational waves to search farther away in deep space or even return to the farthest time available. can.

The history of the universe according to our knowledge

The eLISA team said that the discovery and research of gravitational waves can also open new insights into dark energy, the artifacts of the young universe (also called cosmic strings ), quasars. , the structure of the Milky Way (our galaxy) and helps describe in detail the history of black holes . This is important because astronomers believe that all bright galaxies possess supermassive black holes at their center, so learning about black holes will help better understand the evolution of main galaxies. Gravitational waves can also expand the Hubble constant - a constant that describes the expansion of the universe and allows for new studies of general relativity.

The problem with gravitational waves is the detection of ripples in space-time that require extremely high-sensitivity devices. The proposed method is a laser interferometer, whereby a laser will interfere with itself when transmitted over long distances. The interference pattern will give scientists a tool to measure the smallest movements in space. However, this is also a technique that requires distance of distance calculation and almost absolute stability.

Laser interferometer on eLISA

Previous attempts to probe gravitational waves from the Earth were not effective because the baseline was not large enough and especially there were too many shocks surrounding the exploration. Therefore, the eLISA mission will include a 3-spacecraft squadron and conduct exploration from space. The three ships will fly in a precise formation to create a giant Michelson interferometer floating in space with a baseline of up to 1 million kilometers. This system works by multiplying the differential changes in the length of the baselines when attractive ripples stretch and narrow the space-time.

The "scientific ships" (according to the team's call) and their loads are specially designed so that each ship's operation does not affect each other. Although it will take another 20 years for the new eLISA squadron to be launched into orbit, but the design of the fascinating interferometry, telescope and reference sensors has been planned and prepared for a decade. by.

eLISA will fly around the Sun at 1 Lagrange point (L1 - point between the Sun and Earth where gravity is balanced, allowing objects to stand still). The ships will maintain their position according to an almost triangular formation, the distance between ships is between 1 and 5 million km. Thereby, the squadron will fly in a trajectory called "Cartwheel" around a common mind. The vessel can be kept at a constant distance from the Earth and allows travel up to 70 million km away according to the communication limits between eLISA vessels.

Inside each vessel, thermal stability is the test mass. These are cubes, 46mm in size, made of solid, non-magnetic gold-platinum alloy. They drift freely in vacuum chambers. This may sound redundant in space but the ships continuously release air when operating, so the test volumes need to be protected. In addition, ultraviolet light will glow in the vacuum chamber periodically to release electrons and keep the environment inside the vacuum chamber neutral to electricity before the possibility of being bombarded by cosmic rays.

Simulation of eLISA's micro push system

The entire eLISA system will automatically move to maintain the central position of the test blocks. Each vacuum chamber has capacitive sensors that monitor changes in the test block's correlation with the ship and the laser interferometer will measure the change between the test blocks together. If the test unit leaves the center, the ship's micro push system will automatically be activated to adjust their position.

The measurement activity of eLISA is carried out through a 20cm diameter telescope. The telescope will emit a Nd: YAG laser along the base length (Nd: YAG is a solid laser using a Yttrium-Aluminum-Garnet crystal), which is covered with a rare Neodymium element of the shell. Earth to act as an activation medium The wavelength of Nd: Yag is 1064nm in the near infrared spectrum. If optical bending occurs , the received light will interfere with the light of the original laser. Interference allows the system to calculate the motion moments of test blocks with extremely high sensitivity. On eLISA there is even a system to remove laser noise.

With the use of laser interferometers, eLISA can use test masses to accurately measure the distance to the ratio below the picometer (less than 1/31 Helium atom size). This allows eLISA to detect gravitational waves at frequencies from 0.1mHz to 100mHz and can determine the frequency, phase and polarity of waves. In addition, eLISA can observe the whole sky and analyze / distinguish overlapping signals.

Simulation image of 1 of 3 eLISA spacecraft

The first goal of eLISA will be small double stars. They will act as a calibration tool because the positions and cycles of the stars have been determined. This allows researchers to apply extrapolation and create reliability for future exploration.

Time Sumner, a leading physics professor at the eLISA team at the Royal London Institute, said: "This mission will allow us to study the universe in a whole new way - we will be" settled. Listen "as well as see. Over the centuries, astronomy has lifted the mystery of the electromagnetic spectrum with light, infrared, X-rays, etc. With gravitational waves, we will have a method. Just like we used to watch TV without sound, now there are both sounds and pictures to feel more clearly what's happening, the possibilities of gravitational waves are really mesmerizing. or we will be able to solve questions about black holes, observe the gravitational force more accurately than before and even You can know what happens in seconds after the Big Bang ".

LISA Pathfinder in the space compartment with scientists at ESA

To test eLISA technology, ESA will launch LISA Pathfinder (LPF) in 2015 under a six-month mission to test the systems to be used on eLISA, the effectiveness of optical measurement methods and technology limitations.

eLISA is classified by ESA as the L3 (Large) mission class and will be implemented after the L2 mission - extended X-ray research in 2028 by ESA.