A Couple of Mission Updates

Polaris Dawn is go for Tuesday Morning, Sept. 10

Liftoff is scheduled for 0738 UTC, 3:38 AM ET.  As before, there are two additional launch opportunities within the four-hour window at 5:23 AM ET and 7:09 AM ET. If needed, backup opportunities are available on Wednesday, September 11 at the same times.   

The US Space Force weather squadron isn't very optimistic here, citing a 40% chance of acceptable weather - also known as a 60% chance of bad weather.   

Considering the crew has been in isolation on the Cape since August 20, this has to be a hardship for them. Flight commander Jared Isaacman has said that because of the lack of room left on the Crew Dragon with all the things they're bringing that he wanted to make sure the weather for both launch and landing were less of a factor than on conventional missions. He's concerned they don't have enough room for the food and supplies they'd prefer to bring.  All the previous schedule shifts we've seen have been due to weather.

In the wake of scrubbing ESCAPADE 

The next big, interesting, planetary mission is Europa Clipper headed for the Jovian moon Europa to search for conditions favorable to life under the ice surface of the ocean covering the moon. The mission just completed the probe's pre-launch review and is now cleared to prepare for its mission, NET October 10th at 12:31PM ET on a Falcon Heavy from pad 39A on the KSC side. This is where the Polaris Dawn capsule and its Falcon 9 booster are currently waiting for its launch. 

A major issue in the design review was raised about transistors (MOSFETs - or metal-oxide-semiconductor field-effect transistors) used in various places on Europa. Other users have reported these transistors have failed under radiation conditions they were certified to work under. Within days, the JPL had verified that samples of the transistors they had used also failed.  

“That led to four months of around-the-clock testing at multiple locations around the country,” said Jordan Evans, Europa Clipper project manager at the Jet Propulsion Laboratory, as engineers sought to understand how various systems on the spacecraft were affected by radiation damage to those transistors. 

“This was a huge lift, and I think ‘huge lift’ is a huge understatement,” said Laurie Leshin, director of JPL, at the briefing. It involved testing not just at JPL but also the Goddard Space Flight Center and Applied Physics Laboratory.

Those tests found that none of the systems on Europa Clipper were impaired by potential damage to those transistors. “Every one of those circuits is different,” Evans said, with different consequences for failures among the 200 circuits studied. “We determined that we have sufficient margin in every one of those circuits to accomplish this mission.”

NASA continued with Europa Clipper launch preparations, like installing its solar panels, while studying if spacecraft transistors could support the planned mission. Image credit: NASA/Kim Shiflett

Starliner's Return Flight Wasn't Exactly Perfect

Something to keep in mind, from the Ars Technica summary of the return flight.

A couple of fresh technical problems cropped up as Starliner cruised back to Earth. One of 12 control jets on the crew module failed to ignite at any time during Starliner's flight home. These are separate thrusters from the small engines that caused trouble earlier in the Starliner mission. There was also a brief glitch in Starliner's navigation system during reentry.

Starliner fans can't exactly call that flight proof that NASA was too cautious in sending Butch and Suni home by SpaceX.