Chile's 33 trapped miners have been warned that the rescue operation may take several months.
The miners have been stuck 700 metres below ground for three weeks and Chilean rescue workers are now hoping to release them by Christmas. When they were told the news, they're said to have reacted calmly, but the authorities fear they're likely to become depressed.
They have been sent supplies including food in the form of cans of a milk-like drink that is rich with calories and protein and tastes like chocolate with vanilla. Although the miners have lost a significant amount of weight, officials are trying to ensure they don't bulk up before their rescue. Officials say the miners will have to be no more than 90 centimetres around the waist to make it out of the tunnel.
The escape tunnel will be about 66 centimetres wide - the diameter of a typical bike tyre and stretch for more than 688 metres through solid rock.
Chile's health minister said officials were planning exercise and other activities to keep the miners healthy and trim, using some of the passages that remain accessible to the miners. He also said they would be sent anti-depressants to keep their spirits up.
A team of submarine commanders has been called in for advice on close-quarters living and NASA is advising on "life sciences" and giving the men a sense they control their own destinies.