Thiruvananthapuram, Jul 28 (IANS): There is not going to be a replacement for such a great person as former president A.P.J. Abdul Kalam, as he was a "karmayogi", a former colleague at ISRO said on Monday.

Speaking to the media after hearing about the demise of Kalam on Monday, his former colleague S. Nambi Narayanan said he was a great person.

"We were very close as I was reporting to him. I recall working with him. If I were to say in one sentence, I will say he was a 'karmayogi'. The country has lost a great scientist, a great person and one who can never be replaced," said Narayanan, who was exonerated by the CBI in the infamous ISRO spy scandal.

Kalam joined the ISRO in the late 1960s and was there till the early 1980s.

Kalam was the project director of India's first indigenous satellite launch vehicle, which successfully deployed the Rohini satellite in orbit in July 1980.

"We were very close and once when I was in Paris, I had a personal problem involving my young son and he (Kalam) was returning from the US. When I told him about my son, he said not to worry and he took care of him," Narayanan recalled.

Kalam, while being a scientist at the ISRO, used to stay at a very small lodge in the Kerala capital and used to have his food from a small hotel near the lodge.

When he came to the city for the first time after becoming president, he sent out word to the hotel owner and a cobbler who used to repair his shoes to meet him at Raj Bhavan.

Kalam spent some time with the two and they were very pleased.

"The biggest quality of Kalam was that he had no airs and was so unassuming while being with his juniors at the ISRO. He was a very good listener and was always willing to help anyone who approached him with doubts," recalled another former colleague.