Try riot starships (even Mk. I will do), each with 2 force-field modules (and whatever you want for the other modules). Then when you get the shard, move the shard under the riot controls' shields, and then group move the cluster to your home. Then your shard will stay under the protection of those force-fields on the journey back.
Despite how low HP those force-field modules have (by force-field standards), they will significantly increase the expected life span of whatever is under it (in this case, the shard). Plus, the other modules should slow down a large number of the incoming ships (by engine damage) the AI will throw at you, helping the rest of your escort fleet.
Now, if your escort fleet itself is not strong enough to survive the onslaught, then you are not ready to get the second shard yet. Research and build some better stuff, then try again.