The Enemy Stars by Poul Anderson [REVISED PAPERBACK / 1965]
The Enemy Stars by Poul Anderson
REVISD PAPERBACK  BERKLEY BOOKS
Vintage mass market paperback in excellent condition. Like new and unread.
The time is the 23rd century, and ships are crawling outward from Earth into the interstellar depths. It will take them centuries to reach even the nearest stars - but once they do, future travel will be instantaneous, because the ships carry matter transmitters that are not subject to the limitations of lightspeed.
In the meantime, crews can flit back and forth between the ships and Earth, but until now their only purpose has been to stand watch. Until now. At last one ship has made contact with the stars...