Twenty-nine year old Ikenna Iffih, from Boston, Massachusetts, a former computer science student has been sentenced to six months house arrest, two years probation and a ban from using computers for recreational purposes after he repeatedly hacked into the Nasa computer system last year.

Iffih gained access to a Nasa research project over a four month period in 1999 but did not get hold of any sensitive information. He also admitted to damaging another US government defence agency website and causing thousands of dollars worth of damage to another makring company's website.

Iffih pleased guilty to the charges of defacing a commercial website and wilful malicious interference of communications in June.

Nasa have been the target of several hackers recently and over the last six months have arrested at least four others who have attacked Nasa computer systems. One of them, a 20-year old Californian who pleaded guilty to hacking into several of Nasa's computers could face up to a 16 year jail sentence.