From the Raytheon site, http://www.polar.org/hr/employ/index.asp
In addition to your skills and experience, you must meet several other requirements that have been established under the guidance of the National Science Foundation. Failure to meet these requirements may result in withdrawal of an employment offer.
You must be a U.S. citizen or permanent resident.
You must have a valid passport or the ability to obtain one.
After receiving an offer of employment, you must pass:
A pre-employment background check.
A pre-employment drug screen.
Stringent physical and dental examinations.
A psychological examination (winter season only).
Once hired, you must comply with applicable safety, environment, health, and waste management policies and procedures, and be committed to completing your employment contract in Antarctica.
NOTE: Only authorized personnel are allowed on all U.S. stations and vessels. Your spouse, children, pets, etc. are not allowed to travel to Antarctica at any point during your contract.