The case against: We need more proof

If it can be shown that life in our own solar system has appeared not on one planet but on two, the inference is that it will appear on any planet where conditions are right. And the implications here are of vital importance both scientifically and philosophically.

On the other hand, we have to exert a certain amount of caution. The meteorite has lain in the Antarctic for thousands of years, and it certainly came from space. But did it come from Mars?

It is quite true that the composition and characteristics of this meteorite tie in very well with what we believe the Martian surface to be like. Yet we have no positive proof, and I am bound to say that I have definite reservations.

I think we must wait until we can obtain samples that we are quite certain come from Mars. We need to send up an unmanned probe, land it on Mars and bring it back with samples. This was done long ago by the Russians with regard to the moon, and I have little doubt that we can do the same with Mars within the next 10 years.

Even if we do find evidence of life, I am sure that it will be primitive - certainly no little green men, and probably nothing so advanced as even a dandelion.

These latest reports are quite reasonable, but I am not yet confident, partly because I am not absolutely certain that the meteorite is of Martian origin, and because the analysis of these life forms is not yet complete. But certainly, it is a fascinating episode and we must wait and see.

There may once have been life on Mars - there may even be primitive life there now - but I, for one, am unsure.

Patrick Moore

The writer is an astronomer.