# Does a smaller half-life mean that the rate of energy/radiation release is faster?

I had a discussion with someone about using radioactive elements as sources of energy on board long interplanetary voyages. Actually we were talking about going to the moon, and what our source of energy would be. He said that the element that is used should have a long half-life, to have enough of it for the duration of the flight. I said that it would be better to have a short half-life, because the flight is a few tens of hours and since a long one would mean that on average it takes a long time for it to supply significant energy.

----Assumption to be taken: half-life is not probabilistic.----

Does a smaller half-life mean that the rate of energy/radiation release is faster?

The definition of half-life is the amount of time it takes for half an amount(in terms of mass) of a radioactive substance to disintegrate. Since this mass is lost by radiation(energy), does that mean that an inverse proportionality between half-life and rate of energy release exists?

My questions are:

If one has (x) mass of radioactive element (1) which has a half-life (a)

and (x) mass of radioactive element (2) which has a half-life (a/2).

1. Will element (2) release energy faster than element (1)?
2. If the question 1 is true, then does element (2) release energy twice as fast as element (1)?