Lucas Macaj, 23, is a Space Force Guardian based in Colorado
The Colorado Army National Guard has joined the search for a 23-year-old hiker who has vanished inside Rocky Mountain National Park while scaling its tallest peak.
Lucas Macaj of Colorado Springs remains missing Thursday after he was last heard from early Sunday afternoon "when he texted a friend indicating that he was on the summit" of the 14,259 ft. Longs Peak, the National Park Service says.
"It’s hard to think about, especially with all the thoughts that come with it," his girlfriend, Natalie Dodgen, told 9NEWS. "I hope that everyone is doing everything that they can to bring him home at this point."
Park officials announced late Wednesday that "aircraft from the Colorado Army National Guard conducted additional aerial reconnaissance" in the ongoing search for Macaj, but "low clouds at roughly 12,700 feet hampered visibility."
COLORADO HIKER, 23, VANISHES IN ROCKY MOUNTAIN NATIONAL PARK
Lucas Macaj disappeared after texting a friend Sunday indicating that he had reached the summit of Longs Peak, the NPS says. (NPS)
"Team members have been reviewing aerial reconnaissance photos taken on May 13, for any possible clues," they added.
Macaj is a member of the U.S. Space Force, the service branch confirmed to Fox News Digital on Thursday. Peterson Space Force Base in Colorado Springs did not immediately respond to a request for comment.
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Days of searching for Lucas Macaj inside Rocky Mountain National Park have not turned up any clues as to his whereabouts. (NPS/Rocky Mountain National Park)
The NPS says "significant storms moved through high elevations in the park" on the day Macaj vanished, and his vehicle was still parked the following morning at the Longs Peak Trailhead after being reported missing.
Authorities describe Macaj as being 5-feet 9-inches tall with brown hair and green eyes.
"He is likely wearing a dark colored top, tan or brown pants, khaki-colored boots, and a black backpack," the NPS said. "He may also be wearing a beanie and dark colored gloves."
The NPS says "at 14,259 feet, Longs Peak towers above all other summits in Rocky Mountain National Park" and that "the flat-topped monarch is seen from almost anywhere in the park." (NPS)
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In a description of Longs Peak, the NPS warns that "The Keyhole Route can experience winter-like conditions at any time, requiring greater skill and judgment" and to "Be prepared to turn back during sudden, drastic weather changes."
Greg Norman is a reporter at Fox News Digital.
