NASA said it would use high-resolution cameras aboard satellites and the International Space Station to look for possible crash sites in the Indian Ocean. The U.S. space agency is also examining archived images collected by instruments on its Terra and Aqua environmental satellites, said NASA spokesman Allard Beutel.
"Our satellites and space-based cameras are designed for long-term scientific data gathering and Earth observation. They're really not meant to look for a missing aircraft, and obviously NASA isn't a lead agency in this effort. But we're trying to support the search, if possible," Beutel said.
Truss said the aircraft flying on Monday would be focused on searching by sight, rather than radar, which can be tricky to use because of the high seas and wind in the area. Civilian aircraft, which can carry more people, have joined the search.
(Read more: MH370: Timeline of latest developments)
Hijack or sabotage?
Investigators believe someone on the flight shut off the plane's communications systems. Partial military radar tracking showed it turning west and re-crossing the Malay Peninsula, apparently under the control of a skilled pilot.
That has led them to focus on hijacking or sabotage, but investigators have not ruled out technical problems. Faint electronic "pings" detected by a commercial satellite suggested it flew for another six hours or so, but could do no better than place its final signal on one of two vast arcs north and south.
The lack of solid news has meant a prolonged and harrowing wait for families of the passengers, who have complained in both Beijing and Kuala Lumpur about the absence of information.
A Malaysian statement said a "high-level" team briefed relatives in Beijing on Sunday in a meeting that lasted more than six hours.
While the southern arc is now the main focus of the search, Malaysia says efforts will continue in both corridors until confirmed debris are found.
(Read more: Investigators conclude flight MH370 was hijacked)
"We still don't even know for certain if the aircraft is in this area," Truss said of the southern Indian Ocean search.
"We're just clutching at whatever little piece of information that comes along to try to find the place we can concentrate the efforts."