Your ill-timed 'obituary', in News, for the Mars rover Spirit (Nature 463, 600; 2010) brings to mind Mark Twain's saying that reports of his death had been exaggerated. Spirit is alive and well — albeit with limited mobility — and is still returning scientific data from Mars more than six years after landing.

As the Martian winter advances in the months ahead, we expect Spirit to hibernate (not die) by cutting off its communication with Earth and conserving electrical power. Once the Martian spring arrives, we expect Spirit to re-awaken and start doing science once again.

We plan to continue using Spirit's wheels to try to reposition the vehicle. But even if very little motion is achieved, we can still carry out an extended science campaign, including tracking Spirit's radio signal to find out whether the core of Mars is molten or solid.

The day will come when an obituary can be written that lauds Spirit's scientific accomplishments. But that day may not arrive for some time yet.