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I did a quick search and it seems there is neither? - "SPHEREx relies on an entirely passive cooling system — no electricity or coolants are used during normal

I did a quick search and it seems there is neither? - "SPHEREx relies on an entirely passive cooling system — no electricity or coolants are used during normal operations" https://www.jpl.nasa.gov/news/6-things-to-know-about-spherex-nasas-newest-space-telescope/ https://www.jpl.nasa.gov/news/6-things-to-know-about-spherex... edit to add: - "The telescope is passively cooled to below 80 K in low-Earth orbit by three nested V-groove radiators. An additional radiator cools the long wavelength focal plane temperature below 60 K to reduce detector dark current." https://arxiv.org/abs/2404.11017v1 https://arxiv.org/abs/2404.11017v1

dylan604 2y ago
The Spitzer used passive cooling, but only as a method to reduce the amount of coolant required. It still needed a coolant. "One of the most important advances of this redesign was an Earth-trailing orbit.[1] Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from Earth, and consequently require large amounts of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling. The sun shield protected the rest of the spacecraft from the Sun's heat, the far side of the spacecraft was painted black to enhance passive radiation of heat, and the spacecraft bus was thermally isolated from the telescope. All of these design choices combined to drastically reduce the total mass of helium needed, resulting in an overall smaller and lighter payload, resulting in major cost savings, but with a mirror the same diameter as originally designed. This orbit also simplified telescope pointing, but did require the NASA Deep Space Network for communications"[0] [0]https://en.wikipedia.org/wiki/Spitzer_Space_Telescope https://en.wikipedia.org/wiki/Spitzer_Space_Telescope
perihelions 2y ago
I found an explanation of the "v-groove" radiator geometry, if anyone else was curious about it: (.pdf) https://ttu-ir.tdl.org/server/api/core/bitstreams/71aee1e9-3f65-466f-a804-2737eefd2bed/content https://ttu-ir.tdl.org/server/api/core/bitstreams/71aee1e9-3...

dylan604 2y ago

The Spitzer used passive cooling, but only as a method to reduce the amount of coolant required. It still needed a coolant. "One of the most important advances of this redesign was an Earth-trailing orbit.[1] Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from Earth, and consequently require large amounts of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling. The sun shield protected the rest of the spacecraft from the Sun's heat, the far side of the spacecraft was painted black to enhance passive radiation of heat, and the spacecraft bus was thermally isolated from the telescope. All of these design choices combined to drastically reduce the total mass of helium needed, resulting in an overall smaller and lighter payload, resulting in major cost savings, but with a mirror the same diameter as originally designed. This orbit also simplified telescope pointing, but did require the NASA Deep Space Network for communications"[0] [0]https://en.wikipedia.org/wiki/Spitzer_Space_Telescope https://en.wikipedia.org/wiki/Spitzer_Space_Telescope

perihelions 2y ago

I found an explanation of the "v-groove" radiator geometry, if anyone else was curious about it: (.pdf) https://ttu-ir.tdl.org/server/api/core/bitstreams/71aee1e9-3f65-466f-a804-2737eefd2bed/content https://ttu-ir.tdl.org/server/api/core/bitstreams/71aee1e9-3...