Might not be time to get Sasha's body from Mars this trip. But what about another trip (if they follow the old timeline/plotline somewhat)? As a meta perspective of course. They can't assume they will even make it to Iscandar at this point. They can't even assume they will make it past the Gamilus Fleet at Pluto at this point.
As we've not (I assume) seen much more than the preview of this episode, we can't be entirely certain about what is going on by the time
Yamato gets to Mars. In the original version is was the Moon to Mars and they were under attack by another Gamilas carrier and its fighter wing.