The lunar craft to be used in India's first unmanned mission to the Moon [Images] -- Chandrayaan-I -- successfully passed a test for its endurance in harsh space environment crossing a major milestone in preparation for the odyssey expected some time next month.

The two-week vacuum test to evaluate the thermal design of the spacecraft and to verify its endurance in the harsh environment of space has just been completed at Indian Space Research Organisation Satellite Centre in Bengaluru [Images], sources in the space agency said.

"The test was satisfactory," an ISRO official told PTI on Thursday.

"Environment and accoustics tests will follow, and the pre-shipment review is expected by this month-end," the official added.

A formal announcement on the date of the eagerly awaited launch is expected to be made by Chairman of the Bengalur-headquartered ISRO G Madhavan Nair next week.

An ISRO official said on condition of anonymity that October 22 is the first available date for the ambitious launch and the launch window has been fixed for between October 22 and 26.

ISRO officials said it is an "exceptional example" of international collaboration towards exploring the moon.

The nearly 1,400 kg Chandrayaan-I satellite will be launched by the 316-tonne Polar Satellite Launch Vehicle (PSLV-XL) from Satish Dhawan Space Centre at the spaceport of Sriharikota.

There are six scientific payloads from NASA [Images], ESA and Bulgaria in addition to the five Indian instruments onboard Chandrayaan-I, which is an unique exploratory mission that will undertake full mapping of the moon which does not exist today.

The spacecraft will however not land on the moon.