What the heck is that thing?

It’s fair to assume that question was on the minds of many people who traveled along Colo. 128 south of Boulder this week if they happened to catch a glimpse of what appeared to be a large, silver projectile perched alongside the highway and pointed north toward town.

The object — mounted on a long arm protruding from the back of a Ball Aerospace pickup truck — had been set up about 1 ½ miles east of Colo. 93 on the north side of Colo. 128 since Monday, according to several passersby.

Mark McDade, who works at the nearby National Wind Technology Center, finally pulled over Wednesday morning after driving by all week.

The people at the site told McDade they worked for aerospace companies Ball and Lockheed Martin, but didn’t reveal much else.

“I asked (one person) if it was military technology, and he said, ‘No.’ Then I asked him if it was commercial proprietary, and he literally kept his mouth shut,” McDade said with a chuckle. “The hush-hush nature of the whole thing is what really got me curious.”

On Thursday, though, Lockheed officials threw cold water on the mystery when spokeswoman Suzanne Smith wrote in an email that the company was “just testing one of its sensor technologies.”

She wouldn’t elaborate.

But for those who spotted it by chance, the object — which Lakewood resident John Henry dubbed a “bullet-looking missile thing” — certainly sparked some healthy curiosity.

A small group of workers milled around the test site Thursday morning. Two panel trucks loaded with other equipment were parked nearby, as well as a rented RV, a portable toilet, several cars and another odd-looking cylindrical object — this one with a black, plastic nose instead of the pointed tip of its more menacing counterpart.

Despite several motorists and a few cyclists pulling over to inquire about the eye-catching scene, the workers on site were mostly tight-lipped, with one man acknowledging only that they were doing “engineering testing.”

The man refused to give his name or say who he or anyone else at the site worked for. At some point after a Daily Camera reporter arrived, somebody covered up the Ball insignia on the side of the pickup truck bearing the pointy sensor.

Henry, who had brought his mountain bike to the nearby High Plains trailhead, said he’d seen the object at two sites along Colo. 128 — the second one located just east of McCaslin Boulevard — every day this week when driving up the highway from the Broomfield area.

“I’m not too worried about it,” he said.

McDade said the person he spoke to Wednesday morning at one point gestured toward some of his colleagues and the missile-like cylinder as she said, “Those guys made a rather unfortunate choice of enclosure.”

Officials with Ball confirmed Thursday that they are a subcontractor on the project, but deferred specific questions to Lockheed.

Lockheed’s Smith said that testing along the public roadway was permitted by the Colorado Department of Transportation, and funded internally.

She said testing concluded Thursday.

When asked to further explain the nature of the sensor technology being tested, she said that information was “competition-sensitive.”

Joe Rubino: 303-473-1328, rubinoj@dailycamera.com or twitter.com/rubinojc