The escape pod’s been jettisoned, with Martha inside; that’s the worst thing that could’ve happened, because it’s being pulled towards the sun. The heat shields won’t last much longer; she and Riley won’t live long enough to be burned alive, which Martha supposes is some small consolation.
She’s not giving up hope though, not yet. The Doctor will save them, she has to believe that; if there’s any possible way, he’ll find it because he’s brilliant.
But just in case, she’ll phone her mum. If she doesn’t make it, nobody will ever know, but at least she’ll have said goodbye.