SPHEREx implements a simple and robust design that maximizes spectral throughput and efficiency. SPHEREx achieves this with no moving parts except for one-time deployments of a sunshield and aperture cover. Design features have been proven effective on previous missions, and include:
- 20 cm all-aluminum telescope with a wide 3.5° x 7° field of view, imaged onto four 2k x 2k HgCdTe detector arrays. These H2RG arrays have been qualified for space observations by the James Webb Space Telescope, and are built on a long successful history of space instruments using arrays in smaller formats.
- Four space-demonstrated linear varable filters (LVFs) to produce spectra. The spectrum of each source is obtained by moving the telescope in the dispersion direction of the LVF in discrete steps. This method was demonstrated by LEISA on New Horizons to obtain excellent spectral images of Jupiter and Pluto.
- A telescope that is radiatively cooled to ≤ 80K and two detectors that are cooled to ≤ 55K with 320% total margin on the net heat load. The thermal methods employed on SPHEREx have been previously demonstrated by Planck, Spitzer, and WISE.
|Telescope Effective Aperture||20 cm|
|Pixel Size||6.2" x 6.2"|
|Field of View||2 x (3.5° x 7.0°); dichroic|
|Resolving Power and Wavelength Coverage||λ= 0.75- 4.18 µm; R=41.4
λ= 4.18 - 5.00 µm; R=135
|Arrays||2x Hawaii-2RG 2.5 µm
2x Hawaii-2RG 5.3 µm
|Point Source Sensitivity||18.4 AB mag (5σ) per frequency bin referenced at 2 µm. Sensitivity has 380% total margin to science requirement||Cooling||All-Passive|
|2.5 µm Array and Optics Temperature||80K|
|5.3 µm Array Temperature||55K|
|Payload Mass||68.7 kg|