Under 28 USC 1866
(g) Any person summoned for jury service who fails to appear as
directed may be ordered by the district court to appear forthwith and
show cause for failure to comply with the summons. Any person who
fails to show good cause for noncompliance with a summons may be fined
not more than $1,000, imprisoned not more than three days, ordered to
perform community service, or any combination thereof.
There are certain statutory requirements disqualifying a prospective juror, such as being unable to speak English, not being a citizen, of having a conviction or pending felony charge, otherwise you are at the mercy of the court, and may vary from federal court district to district. Typically, however, you just need to explain the hardship that jury duty would pose.
In California, failure to appear for a state jury summons is treated as contempt of court, for which you can also be punished. However, disobedience would have to be willful, not just negligent. California follows a "two strikes" policy, meaning that after you miss the first obligation, they send a more strongly worded second notice.
There is no real likelihood that you will be prosecuted if you don't receive and respond to the jury summons, as long as you were not willfully ignoring the summons. When people leave the country for a long period, they typically leave someone "in charge" to take care of details (property taxes etc.). If you failed to give your assistant an instruction regarding jury summonses, or if they willfully tossed the notice, you would not be held criminally or civilly liable.