NASA has cut ties with a private group that intends to launch an asteroid-survey mission. The decision clouds the prospects of the only large-scale space telescope being developed to seek space objects that have the potential to wreak havoc on Earth.

NASA said Tuesday that it has ended its commitment to provide analytical and data-downlink support to Sentinel, a US$450-million satellite designed to spot 90% of near-Earth objects (NEOs) larger than 140 metres. NASA said the decision was made because the project has missed its development deadlines, and the money held in reserve for Sentinel operations is needed elsewhere. 

The Sentinel team vows to continue, but it is unclear whether the project can overcome perennial cash-flow problems and NASA’s vote of no confidence. Money for the spacecraft’s development was supposed to come from private donors, but fund-raising has lagged behind expectations.

Sentinel’s struggles are “disappointing,” says Timothy Spahr, CEO of space consultancy NEO Sciences. If the mission ever launches, it has the potential to make a big dent in the estimated half-million-plus undetected and potentially devastating asteroids that come within 45 million kilometres of Earth’s orbit. An object no more than 55 metres across ravaged trees across 2,000 square kilometres of Siberian forest in the so-called Tunguska event of 1908; a direct hit from a Tunguska-sized asteroid could lay waste to a large city. Of the roughly 363,000 near-Earth asteroids as big as the Tunguska object, only 565 had been discovered as of a year ago.

A steady flow of scientific reports has urged the launch of a space-based telescope dedicated to finding these objects. In 2005, the US Congress passed a law requiring NASA to track down 90% of all objects 140 metres and bigger by 2020. The space agency’s NEO budget has risen dramatically in recent years, but NASA continues to rely primarily on a patchwork of ground-based telescopes for NEO surveillance and expects to miss its deadline.

Hoping to make progress toward that goal, NASA signed a 2012 agreement with the B612 Foundation, a non-profit group in Mill Valley, California, led by former astronaut Ed Lu. The agency agreed to provide assistance worth roughly $30 million if B612 met a number of development milestones. But the group has missed its technical deadlines and raised only $1.6 million in 2013, the most recent year for which figures are available. The foundation needs roughly $30-40 million annually to keep Sentinel on track.

NASA notified B612 in August that it was dissolving their agreement. The end of the deal, first reported by, “in no way changes the resolve of the B612 Foundation to move forward,” B612 Foundation CEO Lu says in a statement. But it may sway the chances of a different survey effort: NEOCam, an asteroid-spotting mission now under consideration by NASA. The NEOCam team, headed by astronomer Amy Mainzer of the Jet Propulsion Laboratory in Pasadena, California, expects to learn in the next few weeks whether it has made the first cut for funding from NASA’s Discovery programme, which supports relatively modest space missions. If NEOCam is selected, it will compete with a small number of other projects for a 2021 launch slot.

I have nothing but admiration for the hearts and dedication of the Sentinel team,” says planetary scientist Richard Binzel of the Massachusetts Institute of Technology in Cambridge. “But this is such a large problem to tackle that it is going to require a dedicated space agency effort.”

Some scientists think that without Sentinel as a distraction, NASA is more likely to fund a dedicated NEO telescope. “The promise of something for free was impeding NASA from making what was seen as a critical investment,” says NEOCam team member Mark Sykes of the Planetary Science Institute in Tucson, Arizona.

Sentinel isn’t the first ambitious NEO-spotting project to fall by the wayside, Spahr notes. “There’s a long history of things that didn’t work. But failure drives things forward.”

This article is reproduced with permission and was first published on September 29, 2015.