"Firefly" and "Serenity" may be dead, but actress Jewel Staite doesn't hesitate in chiming in with the old cliche that no one (and no thing) stays dead in science-fiction.

"I think it's safe to say, for now, that we're finished," Staite told reporters during a Wednesday phone conference. "There's always been talk of a couple more movies being done in the future, but I think it's up to Joss [Whedon]. But I would do it in a heartbeat. I had such an amazing time on that show."

In the meantime, Staite has taken over the role of Dr. Keller, the main medical official in "Stargate: Atlantis," which premieres its fourth season Friday night on SciFi Channel. She takes on a role originally played by Paul McGillion as Dr. Carson Beckett, and she knows she has a lot of expectation to live up to.

"All I can really say is that I hope I'm bringing something new and interesting to the dynamic and relationship between the characters," Staite said. "I don't view myself as replacing anyone. It would seem presumptuous of me to say that I would be replacing him as I know how beloved a character he was. I can only hope that people give Keller a chance, and enjoy her. She has a lot of complexity, and she is a lot of fun. And there is definitely a lot of surprises coming to her personality later this season."

At the same time, she knows that in today's dramatic television world, no one is safe, no matter how popular they are.

"I definitely flip to the last page every time I read a script just in case," Staite said. "I've been lucky because I usually don't have to go out on any field missions, so I am out of danger so far."

Staite has a number of scenes in the upcoming fourth season with Amanda Tapping, who joins the show after 10 years on "Stargate SG-1" as well as David Hewlett's character of Rodney McKay, but it's series star Joe Flanigan she says she wants more time with.

"I hardly get any scenes with Joe," Staite said. Keller "and Carter have bonded because they are both new. She's bonded with McKay mostly because she likes to tease him and flirt with him and make him feel uncomfortable, and she's bonded with Ronon (Jason Momoa) a little bit."

While Dr. Keller may be a strong female character much like Tapping's Samantha Carter and Rachel Luttrell's Teyla, it doesn't mean she is without some human issues.

"She is a bit of a scaredy-cat, and not very good in dire or violent situations," Staite said of Keller. "She scares very easily. But as for her biggest strength, she is real great under pressure. That is when she's at her best. Anything that has to do with medicine of a complicated medical situation, she is just there, she is on it."

As long as the medical ward isn't too high up, because Keller also is afraid of heights, Staite said.

"Stargate: Atlantis" premieres its fourth season Friday at 10 p.m. ET on SciFi Channel.