The Nasaghasts are a trio of violent wraiths that reside in the Kennedy Space Center. Originally the crew of a shuttle mission that was sabotaged, when they died in the explosion they were exposed to "crazy space radiation" that somehow turned the three of them into the ghasts. Ever since, they have haunted they Space Center, remaining dormant until a NASA astronaut is attacked or threatened.
When this happens, the Nasaghasts awaken and hunt down the attacker. They are relentless in their pursuit and will not rest until their target has been killed. However, they will not act preemptively to protect an astronaut; only once the attack or threat has been made will they react. They will also only respond when the attack is made against someone who is an actual astronaut. When Dan McNinja attacked a NASA employee following the shuttle explosion, this did not provoke the Nasaghasts, since due to space missions being suspended, the employee was merely a "scientist" and not an "astronaut". It seems they will also stand down if the astronaut who had been threatened calls off the attack.
Two of the three Nasaghasts were destroyed by Dr. McNinja with holy shurikens when he attempted to steal a shuttle with the help of another version of Chuck Goodrich to prevent a future where the Earth is conquered by dinosaurs from outer space. Doc had provoked the Nasaghasts when he punched an astronaut who had discovered their intrusion. In the bad future where the invasion occurs, the remaining Nasaghast is awakened when this same Chuck Goodrich participates in the attack by the human resistance on the dinosaur army. It swoops in and destroys any dinosaur that threatens Chuck, but only Chuck. When a Horrorsaurus nearly wipes out the rest of the human forces, the ghast refuses to do anything about it until Chuck attacks the Horrorsaurus himself. When the Horrorsaurus retaliates by killing Chuck, the Nasaghast destroys the Horrorsaurus before returning to the Kennedy Space Center.