Alpha Centauri is the closest star system to our own, only four light-years away. It consists of three stars: Alpha Centauri A and B, which are similar to the Sun, and Proxima Centauri, a red dwarf that hosts the nearest known exoplanet, Proxima b. Could there be other planets orbiting these stars, perhaps even ones that could support life?
A new satellite mission aims to find out. The mission is called TOLIMAN, after the ancient Arabic name for Alpha Centauri. It is a collaboration between the University of Sydney and EnduroSat, a Bulgarian company that specializes in micro-satellites.
The mission is also supported by Breakthrough Initiatives, a philanthropic organization that funds projects related to the search for extraterrestrial intelligence.
The goal of TOLIMAN is to detect Earth-like planets in the habitable zone of Alpha Centauri A and B, the region where liquid water could exist on the surface.
To do this, the mission will use a technique called astrometry, which measures the tiny wobbles of stars caused by the gravitational pull of their planets.
This method is complementary to other techniques such as transit photometry and radial velocity, which look for dips in starlight or shifts in star spectra due to planetary orbits.
TOLIMAN will employ a custom-designed space telescope that will fit inside a 12-liter cube. The telescope will have a high-resolution camera and a coronagraph, a device that blocks out the bright light of the stars to reveal their fainter companions.
The telescope will also use a novel optical system called aperture masking interferometry, which combines the light from different parts of the telescope’s mirror to create interference patterns that reveal information about the star system.
The mission will launch in 2024 and orbit the Earth for two years. During this time, it will observe Alpha Centauri A and B for about 20 minutes every day, collecting data that will be analyzed by scientists on the ground.
The mission hopes to achieve an astrometric precision of 10 microarcseconds, which is equivalent to measuring the width of a human hair from 500 kilometers away.
If TOLIMAN succeeds in finding planets around Alpha Centauri A and B, it will open up new possibilities for further exploration and characterization. For instance, future missions such as James Webb Space Telescope or Breakthrough Starshot could target these planets for spectroscopic analysis or direct imaging, looking for signs of atmospheres, oceans, or even life.
TOLIMAN is an ambitious and innovative mission that will push the boundaries of satellite technology and exoplanet science. It will also bring us closer to answering one of the most profound questions in human history: are we alone in the universe?