LOS ANGELES -- NASA announced the end of its Opportunity rover's mission on Wednesday, 15 years after its arrival on Mars.

The announcement was made at a press conference at the agency's Jet Propulsion Laboratory in Pasadena, California, following NASA's last attempt to communicate with the rover on Tuesday night which got no response.

The rover has not been heard from for eight months since a planet-wide dust storm on the red planet in June last year. Mission team members have tried to rouse the rover ever since, but failed to set up communication again.

"Saying goodbye is hard, but it comes the time," said John Callas, project manager for Opportunity.

The golf-cart-sized rover far exceeded its planned 90-day mission lifetimes. It has traveled over 45 kilometers on Mars and worked for nearly 15 years.

Opportunity landed on Mars on Jan. 24, 2004. First among the mission's scientific goals was to search for and characterize a wide range of rocks and soils for clues to past water activity on Mars.