Thank you very much Sandoval
Yes, Sigrid all alone on the ship does hark back to Ripley from the Alien films. In fact the Majestic's
final log entry is a homage
(or rip off!) of the final entries of Ripley in the first Alien film and Elizabeth Shaw at the end of Prometheus - the last woman standing and all that!
As for the torus, it's either a macguffin with no real purpose other than to sit there and be mysterious, or there is some earth-shattering hidden motive to its construction.
I'll let you decide which!