HOUSTON — The B612 Foundation has completed an independent program concept and implementation review of the Silicon Valley nonprofit’s proposed asteroid-hunting Sentinel Space Telescope, according to Mission Director Harold Reistema.

The first privately funded deep space mission, Sentinel is a five-plus-year initiative to detect and track near Earth asteroids (NEAs) that pose a future collision threat, The ambitious project, which will rely on an equally challenging fund-raising campaign to meet a price tag estimated at “several hundred million dollars,” is headed toward a system requirements review in the second quarter of 2013 and a target launch in 2017-2018, Reitsema told an Oct. 11 teleconference.

“We have a real concept now for how we want to do the mission,” says Reitsema, a former director for science mission development at Ball Aerospace of Boulder, Colo., Sentinel’s prime contractor. “Ball has helped put together a very good mission design based on previous missions that have successfully flown in space, retiring a lot of the development effort.” Those projects include NASA’s Kepler and Spitzer space telescopes.

The two-day, mid-September review was carried out in Boulder by an independent, 11-member Sentinel Space Review Team chaired by Thomas Gavin, former director for Solar System Exploration at NASA’s Jet Propulsion Laboratory, and comprising veteran engineers from NASA, industry and the military.

The session addressed mission requirements; spacecraft subsystems; development, test and verification strategies; and development and test plans for the primary long-wavelength IR detector; as well as management and organizational requirements.

“We feel this mission is absolutely crucial,” said Ed Lu, B612 chief executive officer, former NASA astronaut and Google executive, during the teleconference. “We could not be working on anything more important,” he said of the foundation’s decision to establish the special review team and host a nine-member NASA technical review group established under the terms of a Space Act Agreement between the space agency and the foundation. “We want to have the highest chance of mission success.”

The foundation and Ball, working under an initial contract, still are discussing the terms of a longer-term agreement or series of milestone-driven accords to see the project to the launch pad, according to Lu and Reitsema.

Borrowing from Ball’s previous work, the 50-cm Sentinel IR telescope would circle the Sun in a Venus-like orbit, enabling experts to catalogue 90% of the NEA population, including bodies as small as 30 meters. The results would provide years and perhaps decades of warning to respond to an impending impact that could cause regional or global catastrophe.

Founded a decade ago, B612 announced plans for the Sentinel mission in late June, along with a funding-raising campaign. In September, the foundation announced major new donors but not specific contribution amounts. Lu says the organization is not yet prepared to discuss either overall fund-raising goals or mission costs while it negotiates the terms of a development contract.

“We have made very good progress,” he told the teleconference. “It’s progressing like every other large fund-raising campaign. We will release more specifics on our goals in the near future.”