Well surely will include astrobiologists. That is if it is safe enough to send scientists. If it gets as easy as traveling to Antarctica. And if the astrobiologists are able to withstand spending months on end in a tiny enclosed space like that, etc etc. Maybe some will be able to do it.

Do bear in mind this will be an extremely risky mission. I think it will be to Mars orbit for planetary protection reasons. I think preceded by many missions to the Moon and closer at hand.

The first missions to the Moon didn't have any scientists at all. Just astronauts, fighter pilot by training, able to respond quickly and decisively and accurately in a crisis. And all of them able to do the piloting etc. in any emergency.

Only with Apollo 17 did we send our first scientist to the Moon.

I wouldn't be surprised if it was the same for Mars for at least the first two or three missions. Though requiring a different type of specialist. They would have to have immense patience as well as the ability to respond quickly and accurately to any crisis and have lots of technical knowledge about the workings of the spacecraft and its systems.

When they get to Mars, if they are able to drive the rover around in real time via telepresence, in response to requests from Earth they would be able to speed things up hugely compared to control from Earth. And could learn enough science to do experiments. They'd get feedback from Earth within a few minutes when closest to Earth. Sort of like the way it works on the ISS. Still to this day, the people who go up there are primarily astronauts many of them. The scientists who designed the experiments are often back on Earth.

So I think astronauts. And would have to include at least two doctors for safety (in case one of them is ill as a doctor can't treat themselves if they are in some extreme danger e.g. on point of dying). With one doctor, everyone on the crew has a doctor except for the doctor him or herself. That's not much good.

I think as for Apollo the top priority when selecting crew would be safety of the mission. And though there were complaints that Apollo was not science driven - and I think it is important that it is science driven - but it can be science driven and still not include any scientists.

But ideally if you possibly can, include one scientist. Or two. If room for two, large crew, then I'd say one planetary geologist and one astrobiologist. If only one, would be tricky, someone who is cross disciplinary I think one person who is both astrobiologist and planetary geologist at the same time.

If it is a very large crew, or later on, I think it would be great if you had poets, composers, maybe science journalists and so on - good communicators able to convey what is happening to the rest of us and to help it to be a source of inspiration. For science journalists, if she was interested I'd vote for the likes of Emily Lakdawalla  - someone like that, good communicator who can explain things very well to the rest of us. :). And also a trained scientist herself, a planetary geologist.

Or the UK sky at night team, Chris Lintot and Maggie Aderin-Pocock. Anyone like that, people who are good scientists themselves, so are not just baggage, would contribute to the expedition, but also good communicators too, and enthusiastic, able to really let us all feel what is going on. If anyone like that can be found who also wants to go and is also psychologically and physically able to withstand the expedition.

With Apollo - the astronauts were great at what they did. But they weren't the best of communicators, it was rather dry and bland in that respect. They were absolutely the right people to send on such a dangerous mission. But along with scientists selected because they are the very best in their field as much as possible, later expeditions once it is safe to send them - I think should also include people selected so that they are good at communicating to help take the rest of us along with them :).

Of course if you can combine both in one person, someone who is top flight as a scientist in a field that is directly relevant to Mars studies as their speciality - and an excellent communicator, enthusiastic, and able to convey that well too, that would be best of all :).