WASHINGTON — The Aug. 24 failure of a Russian Soyuz-U rocket carrying supplies for the international space station poses no immediate logistical threat to the well-stocked orbital outpost, but U.S. lawmakers immediately seized upon the mishap to push what have become competing visions for NASA’s post-shuttle human spaceflight program.

The Soyuz-U, used to loft Russian-built Progress cargo capsules, is similar in design to the Soyuz-FG that currently is the only means of launching astronauts to the space station. The third stage of those two rockets is “particularly similar,” Michael Suffredini, NASA’s space station program manager, said.

Russian space officials said a third-stage engine malfunction was the cause of the Aug. 24 failure.

The Soyuz-U and Soyuz-FG “are very similar,” independent Russian space expert Aleksandr Zheleznyakov told Space News Aug. 25. “Soyuz-FG is more a modern version with fuel injecting heads in the first and second stage, which increases the load [by] 200 to 300 kilograms.”

Suffredini also said a crewed Soyuz launch scheduled for September and a Soyuz cargo launch scheduled for October could be delayed as a result of the failure.

Another mission, the scheduled Aug. 26 launch of a Russian Glonass navigation satellite aboard yet another Soyuz variant, also has been postponed until further notice.

With NASA’s space shuttle fleet now retired, Russia’s Soyuz rockets and capsules are the only means of flying crews to the space station. There are two international alternatives for delivering cargo, one operated by Europe and one by Japan, as well as two U.S. commercial systems in development and expected to enter service next year.

NASA also is funding development of commercially operated crew transportation systems that it hopes will begin ferrying astronauts to and from the space station starting as soon as 2017. For the longer term, the agency is working on the congressionally mandated Space Launch System (SLS), which along with the planned Orion crew capsule would serve as a government-owned backup to commercial systems and later would be used for missions to deep space destinations.

Although the SLS/Orion and commercial crew programs are billed as complementary, they draw from a funding pool that many believe is not big enough to support both.

In the hours after the Progress vehicle crashed in Siberia, at least two U.S. lawmakers issued statements saying the failure highlights the need to accelerate work on their preferred crew-carrying systems.

Sen. Kay Bailey Hutchison (R-Texas) demanded that NASA immediately start work on the SLS.

“As we have already seen with the multi-year delay with commercial providers of cargo to the space station, the country would greatly benefit from the timely implementation of the NASA Authorization Act of 2010 and development of the Space Launch System as a back-up system,” Hutchison said in an Aug. 25 press release.

Rep. Dana Rohrabacher (R-Calif.) took the opposite tack, calling on NASA to siphon funds from SLS and other programs to the commercial crew program.

“I am calling on General [Charles] Bolden, the NASA Administrator, to propose an emergency transfer of funding from unobligated balances in other programs, including the Space Launch System, to NASA’s commercial crew initiative,” Rohrabacher said in a press release. “NASA could potentially transfer several hundred million dollars from this long term development concept, since the SLS project has not even started, to the more urgently needed systems that can launch astronauts to [the international space station], reliably and affordably.”

The Soyuz-U failure was the second straight mishap involving a Russian rocket. On Aug. 18, a Russian Proton rocket placed a telecommunications satellite into a useless orbit.

The Soyuz-U’s third stage malfunctioned 325 seconds into the flight, according to an Aug. 24 press release from Roscosmos, the Russian space agency. The rocket, which over the years has been among the world’s most reliable, lifted off from the Baikonur Cosmodrome in Kazakhstan at 9 a.m. EDT.

During an impromptu press conference from NASA’s Johnson Space Center in Houston about three hours after the launch, Suffredini said the rocket shut itself down when its on-board computers detected a problem with the third-stage engine.

“Given the trajectory and the energy of the spacecraft at the time, the vehicle impacted in the Altai region of the Russian Federation,” Suffredini said. “And that, unfortunately, is about what we know today, because telemetry was lost shortly thereafter.”

According to a transmission to space station Commander Andrey Borisenko from the top Russian controller at Mission Control Moscow, communications with the rocket and cargo capsule were lost shortly after the launch went awry. NASA rebroadcast the Russian-language message, with an accompanying English translation, prior to its press conference.

“We attempted to contact the vehicle through every possible channel,” the Roscosmos controller, Maxim Matuchen, said.

The Progress M-12M space freighter would have been the 44th to reach the space station. It was carrying 2.9 metric tons of cargo, including about 1.3 metric tons of dry goods — mostly consumables — with “water, fuel and gas” representing the rest of the payload, Suffredini said.

The supplies were bound for the Russian segment of the international space station, Suffredini said.

The loss does not pose an immediate logistical threat to space station operations. The final space shuttle mission, STS-135, dropped off an enormous shipment of consumables back in July.

“We’re in a good position, logistically, to withstand this loss of supplies,” Suffredini said. “The way we had done our logistics with the shuttle flight, we had put ourselves in a position to get to the end of the calendar year 2012.” 

A commission comprising Russian government and industry officials has been set up to investigate the launch failure, Roscosmos said on its website.

Suffredini said he expects NASA will have some visibility into that investigation.

“This has been an extremely bad week for the Russian space industry,” Simon Saradzhyan, a Russian defense and space expert at the Harvard University in Cambridge, Mass., said Aug. 25. “Russia’s only two makers of heavy-lift rockets — Khrunichev and TsSKB-Progress — have seen their rockets fail spectacularly.”

Khrunichev builds the Proton; TsSKB Progress builds the Soyuz rockets.

Saradzhyan said it could be weeks before the Russian investigation roots out the cause of the Soyuz-U’s upper-stage engine failure.

Meanwhile, calls placed Aug. 24 to the press service of Roscosmos in Moscow and to TsSKB-Progress of Samara were not returned.

Nosheen Shakil contributed to this story from Moscow.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.