NASA and the Private Sector - Page 216

Last week, the head of Russia's space agency suggested that the International Space Station was dependent on Russian spacecraft to stay in orbit. But mega-billionaire and Twitter tsunami generator Elon Musk says his own spacecraft can easily fill in to help steer the ISS away from space junk and maintain its altitude.

On Thursday, Dmitry Rogozin, head of Russian space agency Roscosmos, unleashed a tweetstorm in response to the threat of US sanctions that could impact the space program.

In the thread, Rogozin points out that Russian engines help steer the ISS in space. Then the rant took a bizarre turn as he floated the idea of dropping the ISS on our heads should the US and other participating nations kick Russia out of the ISS program.

"If you block cooperation with us, who will save the ISS from an uncontrolled deorbit and fall into the United States or Europe? There is also the option of dropping a 500-ton structure to India and China. Do you want to threaten them with such a prospect? The ISS does not fly over Russia, so all the risks are yours."

Musk answered Rogozin's rhetorical question the following day, replying on Twitter by simply sharing the SpaceX logo.

Russian spacecraft attached to the Russian segment of the ISS are used to adjust the flying laboratory's path and literally help keep it high enough in low Earth orbit so it doesn't fall out of the sky. With some rearranging, SpaceX Dragon capsules could serve the same purpose, according to Musk and others.

Rogozin is known in space circles for his caustic and mocking tone. When sanctions against Russia were announced in 2014, he suggested NASA use a trampoline to send astronauts to orbit. At the time the US was dependent on Russian Soyuz spacecraft to reach the ISS, a situation that changed with the introduction of the SpaceX Crew Dragon vehicle for crewed missions.

Musk responded to this barb six years later, in 2020, after a SpaceX Crew Dragon carried NASA astronauts to the ISS for the first time.

"The trampoline is working," he said at a press conference after the launch.

NASA sent a statement via email late Thursday in response to Rogozin's comments, saying the space agency "continues working with all our international partners, including the State Space Corporation Roscosmos, for the ongoing safe operations of the International Space Station.

"The new export control measures will continue to allow US-Russia civil space cooperation. No changes are planned to the agency's support for ongoing in-orbit and ground station operations. The new export control measures will continue to allow US-Russia civil space cooperation."

After NASA announced its intention to continue business as usual with Russia in orbit, Rogozin backed off his belligerent tone, tweeting, "As diplomats say, 'our concerns have been heard'... In the meantime, we continue to analyze the new US sanctions to detail our response."

There are currently two Russian cosmonauts living on the ISS, alongside four American astronauts and the European Space Agency's Matthias Maurer from Germany.

Next month, three more Russian cosmonauts are set to launch to the ISS. Shortly thereafter, the two cosmonauts on board and one NASA astronaut will return to Earth in a Russian capsule, touching down in Kazakhstan.

What Happened:

Our investigation verified that the payload fairing did not fully deploy prior to upper stage ignition due to an electrical issue. The separation mechanisms (our fairing has 5 of these) were fired in an incorrect order, which resulted in off-nominal movement of the fairing that caused an electrical disconnection. Due to the disconnection, the last separation mechanism never received its command to open, which prevented the fairing from separating completely before upper stage ignition.

Separately, we discovered a software issue that resulted in the upper stage engine being unable to use its Thrust Vector Control system. This led to the vehicle tumbling after the off-nominal stage separation, and caused the end of the mission.

What We Learned:

The root cause of the fairing separation issue was an error in an electrical harness engineering drawing. This harness was built and installed onto the vehicle exactly as specified by our procedures and the engineering drawing, but the drawing error led to two harness channels (pictured below at the locations ‘4’ and ‘5’) being swapped. Prior to the LV0008 flight, we had conducted an end-of-line signal test to verify the separation system and ensure that the system was wired correctly. This test would have been able to detect an error in the harness build or installation, but it was unable to detect an error in the design. The swapped separation channels caused a different deployment sequence than we expected, and this led to the failure to open the fairing. We’ve been able to recreate the failure mode by conducting several experiments at our factory with real flight hardware, one of the benefits of having an active production floor with several launch vehicles in various states of production at the same time.

After determining the root cause of the software issue, we found that our flight control software was vulnerable to a specific “packet loss” failure mode. A missed series of signals resulted in a chain of events, resulting in the upper stage’s inability to recover from its tumble. Although we had designed our software suite to be resilient to packet loss, an unlikely combination of factors caused a failure that we didn’t predict. We have been able to use our hardware-in-the-loop simulator to step through exactly what happened and diagnose the root cause with high confidence.

How We Fixed It:

Through the investigation process we had identified two problems that needed fixing: the harness issue and the software issue. Soon after discovering the harness drawing error, we fixed the drawing and incorporated the change on previously built harnesses. We also implemented a new end-of-line signal test that will allow us to identify this class of issue in the future, if it were to occur, prior to launch. On the software side, we’ve introduced a trio of upgrades designed to make our system even more resilient to packet loss and other similar failure modes. Through constant iteration and extensive testing, we have been able to demonstrate that the changes eliminate the failure mode we saw on LV0008, while making the software suite much more robust.

Here at Astra, iteration and learning are core parts of our culture. I’ve been continuously impressed with the speed, passion, and diligence that the team showed as they worked through these complex issues to identify exactly what occurred and determine the right path forward to resolve each problem. With the root causes identified and corrective measures in place, we’re preparing to return to the launch pad with LV0009 soon — stay tuned!