Given realistic propulsion options, and the requirement that the spacecraft can slow down to orbit its target, the targetstar 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。
2
The specific targetstar has not yet been selected, but its choice will be narrowed by a number of factors.
目前尚未确定某颗目标恒星，但已经将选择缩小到几个因素上了。
3
Although studies of the interstellar medium do not depend on the precise choice of targetstar, the other scientific objectives clearly require that the targetstar has a planetary system.