He mentions tethering spacecraft either to another spacecraft or to a counterweight to allow for rotation and artificial gravity while travelling.

It seems he considers that as Martian gravity is only 38% that of the Earth gravity it shouldn’t be that big a problem as it is with the negligible gravity during space travel, and I guess this might be more easily complemented with an exercise regime.

This could potentially be a serious problem but at the moment we don’t have the data to know if it is a showstopper or not, it’s a shame the Mars Gravity BioSatellite was cancelled, it was a clever idea to be able to get that data in an easy way.

We should at least colonise Mars, at which point the colonists will probably begin the rather slow process of terraforming. We could do that now, with current technology. Zubrin’s updated Mars Direct mission plan is one such example. We now know Mars has abundant water and cave systems which would allow for the creation of propellant via electrolysis, while cave systems would help provide some shelter from radiation and could be sealed to create a higher pressure environment such that only breathing apparatus would be necessary and not entire space suits.

We should colonise Mars because it will open up the pathway to the main asteroid belt which can then be mined and perhaps even inhabited.

People always say we should focus on Earth first but that just seems like an excuse to do nothing, the issues we have on Earth will not be solved by diverting the relatively small amount of resources required for a more ambitious Space Programme towards them.

I think there will be an initial spike of signups, but over the long term the cancellations may outweigh the signups and subscriptions could decrease. Especially if they don’t have another hit show like Stranger Things or Squid Game etc.