These space vessels dump some of their fuel containers after using the fuel to boost their vessel off earth right? Then in space there is nothing which decelerates the vessel on its way to Mars, thus using less fuel per km from then on to get to target site. Scientists using similar technology (who want to create a similar fuel cell device to use for cars) would have to factor in gravity and friction which decelerates our cars plus general non littering road rules. Also our much smaller budgets to buy such a fuel cell for our personal cars. I am optimistic though that the fuel device you are thinking of is quite probable in the near future as fuel efficiency and sustainable energy sourced batteries/fuel devices improves every year.
These space vessels dump some of their fuel containers after using the fuel to boost their vessel off earth right? Then in space there is nothing which decelerates the vessel on its way to Mars, thus using less fuel per km from then on to get to target site. Scientists using similar technology (who want to create a similar fuel cell device to use for cars) would have to factor in gravity and friction which decelerates our cars plus general non littering road rules. Also our much smaller budgets to buy such a fuel cell for our personal cars. I am optimistic though that the fuel device you are thinking of is quite probable in the near future as fuel efficiency and sustainable energy sourced batteries/fuel devices improves every year.