▁multip lied ▁by ▁a ▁meg ap ar sec ▁( a ▁very ▁large ▁unit ▁of ▁length ▁used ▁for ▁meas uring ▁the ▁distances ▁between ▁galaxies ), ▁the ▁result ▁is ▁a ▁human - scale d ▁unit ▁of ▁volume ▁approximately ▁equal ▁to ▁ ▁of ▁a ▁te as po on ▁( about ▁ 3   ml ). ▁ ▁Hub ble - bar n ▁Similar ▁to ▁the ▁bar n - m eg ap ar sec , ▁the ▁Hub ble - bar n ▁uses ▁the ▁bar n ▁with ▁the ▁Hub ble ▁length , ▁which ▁is ▁the ▁radius ▁of ▁the ▁visible ▁universe ▁as ▁derived ▁by ▁using ▁the ▁Hub ble ▁constant ▁and ▁the ▁speed ▁of ▁light . ▁This ▁amounts ▁to ▁around ▁ 1 3 . 1 ▁lit res ▁( 3 . 4 6 ▁US ▁gall ons , ▁ 2 . 8 8 ▁Imperial ▁gall ons ). ▁ ▁Power ▁ ▁Don key ▁power ▁This ▁fac et ious ▁engineering ▁unit ▁is ▁defined ▁as ▁ 2 5 0 ▁w att s — about ▁a ▁third ▁of ▁a ▁horse power . ▁ ▁Pir ate - n in ja ▁A ▁Pir ate - n in ja ▁is ▁defined ▁as ▁one ▁kil ow att - hour ▁( 3 . 6 ▁M J ) ▁per ▁Mart ian ▁day , ▁or ▁sol . ▁It ▁is ▁equivalent ▁to ▁approximately ▁ 4 0 . 5 5 ▁w att s . ▁Andy ▁We ir , ▁author ▁of ▁The ▁Mart ian , ▁revealed ▁in ▁a ▁ 2 0 1 5 ▁interview ▁with ▁Adam ▁Sav age ▁that ▁the ▁Cur ios ity ▁ro ver ▁team ▁at