Mission type | Space observation |
---|---|
Operator | JAXA / ISAS |
Website |
www |
Mission duration | Planned: 3 years |
Spacecraft properties | |
Manufacturer | Institute of Space and Astronautical Science |
Dry mass | Approx. 450 kg [1] |
Power | < 500 W [1] |
Start of mission | |
Launch date | 2032 (planned) [2] |
Rocket | H3 |
Launch site | Tanegashima LA-Y2 |
Contractor | Mitsubishi Heavy Industries |
Main | |
Diameter | LFT: 40 cm
[3] HFT: 20 cm [3] |
Focal length | ~1,100 mm [4] |
Transponders | |
Capacity | 10 Gb/day [1] |
Instruments | |
Superconducting polarimeters | |
Large-class Missions |
LiteBIRD (Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) is a planned small space observatory that aims to detect the footprint of the primordial gravitational wave on the cosmic microwave background (CMB) in a form of polarization pattern called B-mode.
LiteBIRD and OKEANOS were the two finalists for Japan's second Large-Class Mission. [5] [6] In May 2019, LiteBIRD was selected by the Japanese space agency. [7] LiteBIRD is planned to be launched in 2032 with an H3 launch vehicle for three years of observations at the Sun-Earth Lagrangian point L2. [2] [8]
Cosmological inflation is the leading theory of the first instant of the universe, called the Big Bang theory. Inflation postulates that the universe underwent a period of rapid expansion an instant after its formation, and it provides a convincing explanation for cosmological observations. [3] Inflation predicts that primordial gravitational waves were created during the inflationary era, about 10−38 second after the beginning of the universe. [9] The primordial gravitational waves are expected to be imprinted in the CMB polarization map as special patterns, called the B-mode. [9] Measurements of polarization of the CMB radiation are considered as the best probe to detect the primordial gravitational waves, [10] that could bring a profound knowledge on how the Universe began, and may open a new era of testing theoretical predictions of quantum gravity, including those by the superstring theory. [9]
The science goal of LiteBIRD is to measure the CMB polarization over the entire sky with the sensitivity of δr <0.001, which allows testing the major single-field slow-roll inflation models experimentally. [1] [11] The design concept is being studied by an international team of scientists from Japan, U.S., Canada and Europe. [5] [12]
In order to separate CMB from the galactic emission, the measurements will cover 40 GHz to 400 GHz during a 3-year full sky survey using two telescopes on LiteBIRD. [3] [5] The Low Frequency Telescope (LFT) covers 40 GHz to 235 GHz, and the High Frequency Telescope (HFT) covers 280 GHz to 400 GHz. LFT has a 400 mm aperture Crossed-Dragone telescope, and HFT has a 200 mm aperture on-axis refractor with two silicon lenses. [3] [5] [13] The baseline design considers an array of 2,622 superconducting polarimetric detectors. [3] [13] The entire optical system will be cooled down to approximately 5 K (−268.15 °C; −450.67 °F) to minimize the thermal emission, [14] and the focal plane is cooled to 100 mK with a two-stage sub-Kelvin cooler. [3]