Kenta Shinohara, the author of Kanata no Astra Astra Lost In Space posted a picture from the final chapter on Twitter
(The truth is that the picture is fake, he drew it as a joke).
He said he ended up drawing the manga series a bit longer than he planned, and it made the final (physical) volume very thick, the release date was postponed to February, 2018. But he was supposed that readers would be complement with the end.
Check out this article to get more information about the manga:
Via - Official Twitter Account: