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I am pleased that the International Astronomical Union (IAU) has pledged to pay heed to public opinion when naming celestial bodies (24 August, p 7) . I only wish it had done so sooner. I was a member of the first crewed flight around the moon. In training, I chose names for a few of …

I would like to make some corrections to your article on drug trials carried out by the US Department of Defense on volunteer army personnel (3 August, p 6) . I was involved in the trials at Edgewood Arsenal until 1971, not "during much of... the 70s" as you say. Our standards were as high, …

In his look at the wider benefits of vaccines, Michael Brooks describes type 1 and type 2 helper T-cells as competitive, with levels of one going down as the other goes up (17 August, p 38) . He then describes a hypothesis that vaccines reduce allergies by boosting type 1 helper T-cells, reducing the number …

• Parasitic worms secrete chemicals that damp down our type 2 immune response in order to promote their own survival. This has the benefit for their human hosts of reducing allergic reactions.

The creation of a new form of intelligence that humans can't understand (10 August, p 32) might herald the appearance of "zombies" – intelligent entities that can do everything a human can but which are not conscious. The prospect of witnessing them discussing consciousness and giving every appearance of knowing what they are talking about …

The best defence against being tagged with nanocrystals sprayed by drones controlled by border guards, police or the army (24 August, p 19) would surely be to hide in a crowd. If that fails and you become the only person tagged, thwart the system by coating lots of other people and vehicles with the spray, …

Beth O'Leary discusses calls to create a national park to cover the Apollo landing sites on the moon (24 August, p 27) . You can play with words, but a US national park is always going to be seen as just that – a park that belongs to the US, and most of the world …

Elon Musk proposes a Hyperloop transport system to link San Francisco and Los Angeles, carrying passengers inside pods, enclosed within a tube. A fan is to provide air for passengers, and create a compressed-air film beneath the "skis" on which the pods run. This may work in a tube at 0.1 per cent of atmospheric …

Andy Robinson and John Long point out that contraception tilts the reproductive balance towards those genetically programmed to want children, so in the long run it can do nothing to prevent runaway population growth ( 20 July, p 28 and 3 August, p 31 ). This point has been made before, most famously by Garrett …

Reader Martin McCann suggests that there may have been four Hadley cells in the Northern hemisphere, and four in the Southern, in the mid-Cretaceous (17 August, p 31) . Not four, but possibly five. Adjacent cells rotate in opposite directions, and air will always rise at the equator and descend at the poles. It follows …

Both George Ellis and Francis Crick can be right in their apparently contradictory claims about whether causality is "top down" or "bottom up" (17 August, p 28) , if their claims are expressed carefully enough. Reality apparently consists of a small number of basic ingredients, which obey simple relationships with immensely complex consequences. Any given …

You report ideas for laser-propelled interstellar craft (24 August, p 8) . Almost 10 years ago you reported on a similar idea of spacecraft powered by beams of plasma (newscientist.com/article/dn6543) . At the time, I noted that, apart from the issue of maintaining a narrow beam, there were two other problems. First, all the research …

• The proposal is to "phase-lock" the lasers to keep the beam tight – though no one has yet managed this on a large scale. And yes, you would need a laser at the other end to slow the craft down – which will make the first trip interesting.

James Fenton writes to ask a very reasonable question: why not use movement sensing cameras to allow computers to lip-read (20 July, p 29) ? As anyone who has learned sign language or taken a Deaf Awareness course will know, even the best lip-readers can only pick up at most 40 per cent of what …

• Our report on the search for sarin in Syria should have referred to "telltale signs of nerve agent", not of nerve damage (31 August, p 8) . • Wild horses have dragged it from us that in our story on their travails in the US (31 August, p 14) Dustin's surname should have been …