Why is LIFE aiming for mid-infrared, what is the advantage? Why only mid-infrared and not also NIR/Optical? Why do we need to go to space for that?

By going to the mid-infrared regime one probes the thermal emission of the exoplanets (in contrast to investigating exoplanets in reflected light, which is done at optical/near-infrared wavelength). For reference: the thermal emission of Earth peaks at a wavelength of roughly ~11 micron. Measuring the thermal emission of an exoplanet provides constraints on its effective … Continued

Are there examples where interferometry was already used for exoplanet detections?

While interferometric nulling at mid-infrared wavelength was successfully applied at the Multiple Mirror Telescope (MMT) with the BLINC instrument, the Keck Interferometer Nuller (KIN) and the Large Binocular Telescope Interferometer (LBTI) to search for exozodiacal dust disks, thus far no exoplanets were detected using the nulling technique. However, the Hi5 project, currently under development for … Continued

What exactly does nulling mean and why is it so difficult?

(see also above “How does nulling interferometry work?”) The term “nulling” refers to the fact that the light of the central star is effectively suppressed (i.e., “nulled”) so that the significantly fainter signals for nearby planets become detectable. Temperate, terrestrial exoplanets are typically 107-108 times fainter at MIR wavelengths than Solar-type stars. Effective nulling is … Continued

Why does the array rotate? Is this absolutely necessary?

No, strictly speaking, rotating the array may not be absolutely necessary. However, it was shown in the past that such a rotation introduces a temporal modulation of the planet signal that appears to be very robust against instrumental noise effects. This means that the planetary signal can be more easily extracted from the data and … Continued

What is phase chopping?

Phase chopping is a calibration technique. In nulling interferometry there are multiple ways how the beams from the various apertures can be combined (even for the same number of apertures (e.g, four) different beam combination schemes are possible). Phase chopping is a special technique that can only be applied in specific beam combination schemes such … Continued

How does nulling interferometry work?

(Taken from here incl. slight modifications) Nulling interferometry is the name given to an instrumental technique based on interference between several telescopes / apertures and aiming at detecting directly exoplanets. The principle is to create a virtual “blind spot” at the exact location of a bright source, a star, in order to reveal the much … Continued

Why does LIFE plan to use four collector spacecraft and not only two?

The number of collector spacecraft is not defined yet, but if it is higher than 2 the nulling technique can more effectively suppress the stellar light and it is also easier to discriminate axis-symmetric emission (e.g., exo-zodiacal dust) from asymmetric emission (e.g., exoplanet). In addition, the total collecting area of LIFE is important as this … Continued

What is the status/will there be an imaging simulator? What input do you need from the community?

In comparison to including, for instance, a more realistic treatment of instrumental noise, adding another observing mode to LIFEsim that creates mock imaging data has lower priority at the moment. We encourage colleagues interested in science cases requiring an imaging mode for LIFE to create their own back-of-the-envelope estimates for the required sensitivity, spectral resolution … Continued

What are the limitations of LIFEsim? Where/when can I download it?

LIFEsim is in continuous development and new features will be regularly added in the coming months. It will be publicly available at https://github.com/fdannert/LIFEsim. At the moment, LIFEsim features the most relevant astrophysical noise sources, such as geometric stellar leakage, thermal background noise from the local zodiacal dust cloud and from exozodi disks, and the shot … Continued