U.S. photo-intelligence capabilities from space have been "stretched" because of last Friday's explosion of a Titan 34D booster rocket but are "not in crisis," according to a former Defense Department official familiar with such top-secret reconnaissance.

Some nongovernment experts on space programs have said that only one U.S. photo-intelligence satellite is in orbit, a KH11, and that the last of that model was destroyed in the Titan explosion.

They have also said there is no immediate prospect of launching a new photo-intelligence satellite because the KH11's larger successor, the KH12, can only be boosted into space by the shuttle.

Other sources with direct knowledge of the highly classified program take issue with that analysis. Avoiding mention of numbers and types, they suggest that the United States has more photo-intelligence capability from space than a lone KH11.

There are "adequate resources to cover our needs" and more "assets" in space capable of providing visual and other intelligence data than experts outside government realize, the former Pentagon official said.

Another soruce said of the Titan explosion, "It was not a KH11," adding that what was atop the Titan 34D was associated with a "black [intelligence] program."

The major problem created by the second Titan 34D failure in seven months and the Jan. 28 shuttle disaster, he and other sources said, is not loss of two intelligence-gathering satellites but of ways to launch other important, larger satellites.

These include new-generation DSP early-warning satellites, sophisticated Magnum electronic intercept satellites, new KH-12 photo-reconnaissance satellites, SDS information-relay satellites and jam-proof DSCS III high-frequency communications satellites.

"If the number of geopolitical problem areas grow," a former Pentagon official said, "we could run out of capability . . . . But as of now we have adequate resources . . . . "

The sophisticated $800 million KH11 has been the backbone of the space-intelligence system for 10 years. Able to circle the globe in 90 minutes, it can be directed to take pictures almost anywhere on Earth from 150 miles in space and return them immediately.

Last August, a KH11 was destroyed when a Titan 34D failed after launch. At that time, the United States had available what one official called "ample" photo satellites. Because of security, the nongovernment experts said they are not certain how many KH11s were built or orbited and how long they remain operational.

The first KH12 was built specifically to be orbited by the shuttle, which can carry a greater payload than the Titan 34D. But, according to revised shuttle projections, will not be launched until July 1987 at the earliest, Pentagon sources said.

Also waiting to go into orbit aboard a Titan 34D, one source said, is the DSP (defense support program) satellite, which has been ready for several months at Cape Canaveral. Probes into the Titan crashes have delayed its launch.

The DSP would be pushed into stationary orbit far above the Soviet Union where it would be the first device to "see" with infrared detectors signs of a Soviet missile launch.

Three older DSP satellites are in operation and two earlier ones remain in orbit as backups, one source said. Such redundancy offers an indication of the extra capability built into the space-defense program.

The newest DSP, unlike the older ones, can counter Soviet attempts to hide space launches and transmit data in a manner that cannot be jammed, sources said.