Given realistic propulsion options, and the requirement that the spacecraft can slow down to orbit its target, the target star cannot be more than 15 light-years from Earth.

根据实际的推进选择，以及航天器能够减速以环绕其目标公转的需要，目标恒星不能离地球超过15光年。

youdao

This is what you term the 'Secret Space Program' because they use Secret Black Budget funding to go out by magnetic light and not propulsion.

这就是你们所说的“秘密太空计划”，因为他们用秘密黑芽基金，通过地磁光而非推动力对外扩张。

youdao

There isn't enough room here to discuss the various propulsion schemes for accelerating a craft to at least 1/10th the speed of light.

没有太多的余地可以考虑，以将航空器加速到至少光束的十分之一。

youdao

The Death Star project concept falls in a practical sense at the first hurdle as nobody knows how to build a near light speed propulsion engine for it.

FORBES: White House Denies Petition Request To Build A Death Star

The problem came to light when a Propulsion Drive Electronics (PDE) control unit picked up a difference in pressures between the oxidiser and the fuel going through one of the ATV's four "propulsion chains".

BBC: NEWS | Science/Nature | Space truck orbits despite fault

Not worrying about propulsion and working at the speed of light allows for precise engagement and the resulting low collateral damage.

FORBES: U.S. Navy Pioneers Next-Gen Electric Weaponry