The hypothalamus of the brain detects a drop in blood temperature.
The hypothalamus stimulates the pituitary to secrete TSH (thyroid-stimulating hormone).
This hormone stimulates the thyroid to increase its secretion of thyroxine.
The higher concentration of thyroxine increases metabolism and heat production increases.
The blood is warmed back to normal temperature.
Hypothalamus detecting raised blood temperature and reduces its stimulation of the pituitary.
High thyroxine levels inhibiting the release of TSH from the pituitary.
The increased level of thyroxine leads to the limitation or reduction of its secretion.
Body’s metabolism slows down as a result of less thyroxin. The body’s temperature goes down.
The nickel and iron of an iron rich asteroid could be extracted by the Mond process . This involves passing carbon monoxide over the asteroid at a temperature between 50 and 60 °C for nickel, higher for iron, and with high pressures and enclosed in materials that are resistant to the corrosive carbonyls. This forms the gases nickel tetracarbonyl and iron pentacarbonyl - then nickel and iron can be removed from the gas again at higher temperatures, perhaps in an attached printer, and platinum, gold etc. left as a residue.