Ion engines?

<span class="Apple-tab-span" style="white-space: pre"> </span>I was reading the Knight Hawks expanded rules, and I noticed that it states clearly that the chem drives cannot accomplish an interstellar jump and that the atomic drives can.  However, it does not say if ion drives can.  I did the math and, according to the rules (where jump speed is 12,000,000 kilometers and the ion engines accelerate 10,000 km (1 hex) a turn) and ion drives could attain jump speed with a little over 1000 units of hydrogen (with a max load of 10,000 units in all of the engines).  Could they be allowed to jump, jump with a penalty to misjump (due to a less exact acceleration, less rapid deceleration, etc.), or what?  Thoughts?