SPICA (spacecraft)

The Space Infrared Telescope for Cosmology and Astrophysics (SPICA), initially called HII/L2 after the launch vehicle and orbit, is a proposed infrared space telescope, follow-on to the successful Akari spacecraft.

Background

The project is led by the Japan Aerospace Exploration Agency (JAXA), and the telescope will be launched on JAXA's next-generation flagship launch vehicle (H3). The Ritchey-Chrétien telescope's 2.5-metre mirror (similar size to that of the Herschel Space Observatory) is to be made of silicon carbide, possibly by the European Space Agency (ESA) given their experience with Herschel. Currently planned to be launched in 2025, the spacecraft's main mission will be the study of star and planetary formation. It will be able to detect stellar nurseries in galaxies, protoplanetary discs around young stars, and exoplanets, helped by its own coronograph for the latter two types of objects.

Description

It is intended to use a halo orbit around the L2 point; it is intended to use mechanical cryocoolers rather than liquid helium, allowing the mirror to be cooled to 7000450000000000000♠4.5 K (versus the 7001800000000000000♠80 K or so of a mirror cooled only by radiation like Herschel's) which provides substantially greater sensitivity in the 10–100 μm infrared band (IR band); the telescope is intended to observe in longer wavelength infrared than the James Webb Space Telescope.

Large-aperture Cryogenic Telescope^[2]

SPICA will employ a 2.5 m diameter Ritchey-Chretien telescope with a field of view of 30 arc minutes.

Focal-Plane Instruments^[2]

• SMI (SPICA Mid-infrared Instrument): 20–40 μm
  • SMI-LRS (Low-Resolution Spectroscopy): 17-36 μm. It aims at detecting PAH dust emission as a clue of distant galaxies and emission of minerals from planet formation regions around stars.
  • SMI-MRS (Mid-Resolution Spectroscopy): 18-36 μm. Its high sensitivity for line emission with a relatively high wavelength resolution (R = 2,000) enables characterization of distant galaxies and planet formation regions detected by SMI-LRS.
  • SMI-HRS (High-Resolution Spectroscopy): 12-18 μm. With its extremely high wavelength resolution (R = 28,000), SMI-HRS can study the dynamics of molecular gas in planet formation regions around stars.
• SAFARI (SPICA Far-infrared instrument): 34–210 μm

Timeline

The mission has been planned for many years; the launch date as of 2005 was "early 2010s", though as of 2009 a great deal of hardware had been designed but very little built, the SPICA website indicates that in summer 2009 the mission is still at the conference stage,^[3] and the 2009 paper says 'within ten years'.^[4] An internal review at ESA at the end of 2009 suggested that the technology readiness for the mission was not adequate.^[5] In 2010, it was expected to be launched in 2018.^[6] In 2014, it was expected to be launched in 2025.^[7] As of 2016, the earliest possible ESA participation would be as the M5 mission, for a nominal launch date of 2029/2030.

Objectives

As in the name, the main objective is to make advancement in the research of cosmology and astrophysics. Specific research fields includes

• The birth and evolution of galaxies
• The birth and evolution of stars and planetary systems
• The evolution of matter

Discovery science

• Constraints on the emission of ground state Н₂ emission from the first (population III) generation of stars
• The detection of biomarkers in the mid-infrared spectra of exo-planets and/or the primordial material in protoplanetary disks
• The detection of Н₂ haloes around galaxies in the local Universe
• With sufficient technical development of coronagraphic techniques: the imaging of any planets in thehabitable zone in the nearest few stars
• The detection of the far infrared transitions of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium. The very large molecules thought to comprise the PAHs, and which give rise to the characteristic features in the near-infrared, have vibrational transitions in the far-infrared which are widespread and extremely weak
• The direct detection of dust formation in super novae in external galaxies and the determination of the origin of the large amounts of dust in high redshift galaxies

See also

• Akari
• Herschel Space Observatory
• ALMA
• James Webb Space Telescope

References

External links

• Homepage at the Japan Aerospace Exploration Agency
• Homepage at the European Space Agency