This much was clear as investigators began to probe the loss of the SpaceX Falcon 9/Dragon resupply mission loss: The U.S. is at least temporarily without a means of launching astronauts and cargo to the six-person International Space Station, placing a growing burden on Russia to do what it can to keep the outpost minimally equipped and staffed.

So far, tensions between Washington and Moscow over Russia's intrusion into Ukraine have not seeped into the deceptively tenuous U.S.-led day-to-day operations of the 15-nation station program.

However, Russia, too, is recovering from the failed April 28 launch of its Progress M-27M/59 ISS cargo mission. Russia's federal space agency, Roscosmos, hopes to turn the loss around on July 3 with the launching of the Progress M-28M/60 cargo mission, but is slated to use the same Soyuz 2/1a launch vehicle that contributed to an out of control third-stage separation and subsequent uncontrolled re-entry with the loss of more than three tons of fuel, food, clothing, spare parts and other supplies.

That compounded the re-supply difficulties triggered by the Oct. 28 launch explosion of Orbital ATK's third Antares/Cygnus mission as it lifted off from Wallops Island, Va., with 4,800 pounds of supplies and science experiments, some of which were re-gathered and aboard the Falcon9/Dragon.

“We are disappointed in the loss of the latest SpaceX cargo resupply mission to the International Space Station,” Administrator Charles Bolden stated Sunday. “However, the astronauts are safe aboard the station and have sufficient supplies for the next several months. We will work closely with SpaceX to understand what happened, fix the problem and return to flight. The commercial cargo program was designed to accommodate loss of cargo vehicles. “A Progress vehicle is ready to launch July 3, followed in August by a Japanese HTV flight. Orbital ATK, our other commercial cargo partner, is moving ahead with plans for its next launch later this year. “ 

Down to two Russian and one American crew member as a consequence of the Progress M-27M loss, the ISS is provisioned through October, less than the normal six-month supply cushion that NASA's Mike Suffredini, the ISS program manager, and his Mission Management Team prefer. Their expectation was that the lost Dragon CRS-7 mission, one of eight U. S. Russian and Japanese cargo flights planned for the remainder of this year, would restore the six-month cushion by the start of 2016.

"We’re getting close to six months," Suffredini told a June 26 pre-launch news briefing. "It's not a hard requirement. We are trying to get there while still carrying the spare parts we need and of course all the research we need. But I think by the end of the year, we will be closer to where we would like to be, which is closer to about five to six months. We will try to stay there and gradually get ourselves all the way back up to six months."

Also lost aboard the Dragon CRS-7 was the first of two NASA/Boeing-developed International Docking Adaptors that were to fly to the station in 2015. NASA intended to install the IDA-1 with spacewalks late this summer to establish the first ISS docking port for its Commercial Crew Program Boeing CST-100 and SpaceX crewed Dragon vehicles by the end of 2015.

While NASA did not provide a cost estimate for the IDA-1, it is part of a $100 million development effort to equip the station with two docking ports for Boeing and SpaceX commercial crew vehicles.

The installation of IDA-1 on an external station docking port once used by NASA's retired space shuttle fleet was initially planned for late July. The installation was delayed by the Progress M-27M launch failure. Preparations to restore the ISS to six crew, including a second NASA astronaut for the spacewalk, were put on hold until July 22 so that the Russians could demonstrate a recovery from the failed launch before they placed U.S. Japanese and Russian astronauts on a normally reliable FG version of the Soyuz rocket.

Delivery of the second IDA was tentatively planned for the ninth Falcon 9/Dragon CRS mission planned for a Dec. 9 liftoff.

The loss of the first IDA compounds already mounting problems for NASA's Commercial Crew Program, which is seeking $1.24 billion in its 2016 budget to keep efforts in place to resume U.S. launchings of astronauts to the station by the end of 2017. House and Senate appropriators are providing hundreds of millions of dollars below the figure that NASA administrator Charles Bolden has warned is mandatory if the commercial crew initiative is to meet its target.

NASA's station-resupply strategy began to unravel on Oct. 28, as Orbital ATK's (then Orbital Sciences) third NASA contracted Antares/Cygnus re-supply mission exploded seconds after liftoff from Wallops Island, Va.,

An investigation into the cause of the mishap continues, though participants point to a failure of a turbopump in a Russian supplied first stage rocket engine.

Currently, Orbital ATK is prepping for the launching of its next ISS cargo mission in mid-November, using a United Launch Alliance Atlas V launch vehicle as a substitute for the Antares. Orbital intends to resume launchings at Wallops with a re-engined Antares next year.

The European Space Agency's reliable and capable ISS Automated Transfer Vehicle resupply missions came to an end in February after five flights. ESA has moved from ISS re-supply activities to partner with NASA for the development of a service module for the unpiloted Space Launch System/Orion Exploration Mission test flight planned for 2018.

Meanwhile, the space agency is in the process of re-competing its U. S. ISS commercial resupply needs in order to support an extension of station operations from 2020 to 2024.

SpaceX and Orbital led the way with contracts awarded in late 2008, $1.6 billion to SpaceX for at least 12 missions, $1.9 billion to Orbital ATK for at least eight flights.