[Steely Tom]

It always amazes me how long it takes to get to targets like this. Two years, screaming through space, so we can collect a sample, and then wait a few more years to get it back. With these time scales, I wonder how many people see a project through to completion.

Well, one reason is that things in space are just a long way away, but another is that our spacecraft can't carry very much fuel and as a result have to spend most of their time coasting.

In the case of the OSIRIS-REx mission, they used a "gravity-assist" maneuver to accelerate the spacecraft without the use of very much fuel by means of Earth's gravitational field and relative speed with respect to the target; this took a long time to set up.

Without the gravity-assist maneuver the mission would not have been possible; the amount of fuel necessary would have required a more expensive booster rocket to get the spacecraft into space; this would have caused the mission go too far over budget.

[TheZMan]

Thanks for the reply - I get all of that. I do hope in my lifetime we develop a feasible propulsion method that solves these problems.