Tomorrow's Kin — Nancy Kress

The aliens have arrived... they've landed their Embassy ship on a platform in New York Harbor, and will only speak with the United Nations. They say that their world is so different from Earth, in terms of gravity and atmosphere, that they cannot leave their ship. The population of Earth has erupted in fear and speculation.

One day Dr. Marianne Jenner, an obscure scientist working with the human genome, receives an invitation that she cannot refuse. The Secret Service arrives at her college to escort her to New York, for she has been invited, along with the Secretary General of the UN and a few other ambassadors, to visit the alien Embassy.

The truth is about to be revealed. Earth's most elite scientists have ten months to prevent a disaster―and not everyone is willing to wait.