for a few hours the overall heat leak could be about 32 500 kj for the whole mission which could increase the temperature of for example solid hydrogen from 10 k to close to 14 k the triple point of hydrogen in this example with chrs the mass of crew module with radiation shielding could be reduced from more than 26 500 kg to less than 17 800 kg chrs could save nearly 8 800 kg for a 4 m diameter and 8 m long cylindrical crew module and halves the required shielding mass when compared with polyethylene shields such could for example save close to 44 million dollars in launch cost based on 5000 kg estimate for spacex felcon 9 in another embodiment the space thermal system may also include a cryocooler for example a 14k cryocooler in the design to actively store the hydrogen at a desired cryogenic temperature and in for example solid form such a cryocooler for example a 14k cryocooler may be beneficial on space missions lasting more than 1 year fig3 illustrates an embodiment showing a space thermal system and a ground cooling system around a crew module it shows half of a section view of.