WASHINGTON — When the Space Development Agency formally launched in March, it was billed as a major step forward for the Pentagon’s growth in space, with an ambitious plan to launch hundreds of small satellites into orbit.

But just four months into the job, Fred Kennedy, the group’s first director, quit, leading to questions about whether the strategy for which he advocated would last — or if the group itself had a future.

Derek Tournear, a space expert with a background in industry and stints at the Defense Advanced Research Projects Agency as well as Intelligence Advanced Research Projects Activity, stepped in to fill the void left by Kennedy’s departure. But while Kennedy’s vision is largely still intact, Tournear has tweaked it in ways he believes will better serve the Pentagon.

“There’s a lot of small changes,” Tournear told reporters Sept. 18 during the Air Force Association’s annual conference. “The biggest overall change is the ability to operate in a slightly higher LEO [low-Earth orbit] environment.”

One change involves the transport layer — a set of hundreds of satellites, each costing between $12 million and $20 million, which will provide the backbone of the Space Development Agency’s architecture. The transport layer was to sit in LEO at a height of about 400-500 kilometers. Under Tournear, that height shifted to about 1,000-1,500 kilometers, primarily due to advances in off-the-shelf electronics, he said.

That change “flows down throughout the entire architecture” and means fewer satellites are needed in each layer because of the coverage that extends as height increases. However, Tournear noted, the change in satellite numbers won’t be “significant” and will still involve something in the range of 200-300 systems on every layer of the SDA plan.

Other changes were driven by feedback from a July request for information, which Tournear said garnered more than 150 responses.

“We received a lot of technical data that we did not have before, that helped us mature what we think state of the art is for capabilities on the satellites. That will allow us to customize when we actually put out solicitations. A lot of that had to do with exactly what orbits, and the number of satellites, we needed to be able to field for different missions. And then we got another class of responses that were really focused on big-picture architecting on how you can get all these big systems to work together. And that certainly narrowed down what our architecture looks like now,” he said.

He noted that feedback is being factored in with “tranche 0,” a group of dozens of satellites planned to launch in fiscal 2022 as test beds for the broader transport layer.

One change the Pentagon hoped to see but didn’t get was a $15 million reprogramming request. Congress rejected the request earlier this year. Tournear said the denial means the agency will stay on its current path instead of quickening existing processes.

“The reprogramming was only to accelerate our plan. Our plan [is] to hit those dates for fiscal 2022 and fiscal 2024: FY22 is our “tranche 0” (our training tranche), and “tranche 1” is FY24. That was always based on what was in the president’s budget request, which is the roughly $150 million in FY20, no money in FY19. Since we didn’t get that reprogramming request, we didn’t get any money in FY19. It didn’t hurt that plan, but it did prevent us from accelerating beyond that plan.”

In the short term, the SDA is focused on getting a small-scale demo of the transport layer up and running, with two optical cross-links that share information among the satellites as well as beaming down to ground stations. Tournear said to expect contract solicits for that test to come “imminently,” followed by solicitations for experiments for tracking advanced missile threats.