Washinton - A group of scientists who worked on the Phoenix Mars lander last year say they have found evidence of liquid salt water on the red planet.

An analysis of photographs from the lander that explored Mars for six months shows drops of what could be salty, liquid water on the legs of the lander.

They believe the droplets were kicked up from just below the planet's surface when Phoenix landed in May and say they grew and merged over time much as water particles would do.

Washington  - US President Barack Obama praised the people of Northern Ireland for rejecting violence and standing up for peace against "those who would seek to destroy it."

Obama spoke at a White House ceremony Tuesday to celebrate Saint Patrick's Day with the traditional visit by the Irish prime minister, Brian Cowen.

The meeting comes as authorities in Northern Ireland continue to investigate the murders of two British soldiers and a policeman by an extremist splinter group associated with the now disbanded Irish Republican Army (IRA).

Washington  - Ruth Bader Ginsburg, a member of the top court in the United States, said Tuesday she will be undergoing chemotherapy after surgery last month for pancreatic cancer.

The 75-year-old Supreme Court justice said her surgery last month was a complete success and described the chemotherapy treatment as a precautionary move. Ginsburg, the only woman on the nine-member court, said she expected to continue working full-time.

Washington  - The construction of new homes in the United States unexpectedly surged in February, the Commerce Department said Tuesday, signalling that the housing downturn at the heart of the US economic crisis may finally have reached bottom.

Privately-owned housing starts in February were 583,000 at an annual rate, up 22 per cent from January but still down 47.3 per cent from the same month in 2008. Economists had expected a further monthly decline to 450,000 last month, according to a Bloomberg News survey.

San Francisco  - Actress Natasha Richardson was in serious condition at a Montreal hospital Tuesday after suffering head injuries Monday afternoon in a skiing accident, according to Canadian news reports.

The British actress, 45, is a member of the Redgrave acting dynasty and the wife of Liam Neeson. She suffered the injury at the Mont Tremblant ski resort in Quebec, according to People magazine online.