Speeds to totally escape from asteroid surface gravity would, for 3g/cc asteroids of widths 10m, 20m, 40m, or 80m, be in cm/s: .65, 1.30, 2.59, or 5.18, thus at most the length of a finger in 1 second. Thus the asteroid monitoring things could previously have very easily landed simply by sticking out 3-4 long rod effective legs with simple wide feet to halt such a very slow drop down. And now to depart before the small asteroid was to drop into the asteroid collection which it had been lightly propelled to reach, the monitoring equipment etc. could easily use such simple landing legs to effectively jump off at such a slow escape speed. Then it could lightly propel to eventually reach some other recently found asteroid to later land on and monitor.
Such an asteroid monitoring set plus its communications cube only needed ion jets to reach any wanted place in space. Ion jets ionize some elements, then using electrostatic or electromagnetic forces, efficiently accelerate such almost massless ions out to very super fast speeds, a thousand times faster than rocket fuel chemical combustion flames! But such very speedy ion jets were too massively complicated to be forceful enough to lift off from Earth.
Ion jets had been proposed starting quite early in the 1900s, then tried (high up above most of our atmosphere) after the middle of that century. Energy for them can come within our Solar system from simply using Solar light energy converting panels. Then it's sufficient to occasionally just resupply fresh ion jet propellant such as some collected usable asteroid elements.
In the future, if attempting to send anything outside our Solar system, like an unmanned space probe to study some other star's planetary system, ion jets would be the best most efficient now available propulsive system to accelerate out, then later slow down. Best should be to slowly accelerate with a large safely contained antimatter + matter supply for all the required energy, and also a large supply of element(s) which over the years of far travel time can be ionized and sped jetting out super fast.
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