Tag: heat shield

Did SpaceX’s Endeavour capsule have issues with its heat shield during its most recent return to Earth?

9:43 am

According to a May 23rd Space Explored article based on anonymous sources, the heat shield on SpaceX’s Endeavour capsule experienced “dangerously excessive wear upon reentry” because of a propellant leak.

Hypergolic propellant made its way into the Crew Dragon Endeavour’s heat shield, according to sources at SpaceX and NASA who spoke with Space Explored. This hypergolic propellant is used by the Crew Dragon in its Draco engines – hypergolic means that the two parts spontaneously combust upon contact. It is believed that this hypergolic propellant impacted the integrity of the heatshield, causing dangerously excessive wear upon reentry.

NASA however has now bluntly denied these claims:

“The data associated with Dragon’s recent crew reentries was normal — the system performed as designed without dispute. There has not been a hypergol leak during the return of a crewed Dragon mission nor any contamination with the heat shield causing excessive wear,” the NASA statement reads, in part.

“SpaceX and NASA perform a full engineering review of the heat shield’s thermal protection system following each return, including prior to the launch of the Crew-4 mission currently at the International Space Station,” the NASA statement continues. “The heat shield composite structure (structure below the tile) was re-flown per normal planning and refurbishment processes. The thermal protection system on the primary heat shield for Crew-4 was new, as it has been for all human spaceflight missions.”

Such a flat out denial by NASA strongly suggests that the anonymous sources relied on by Space Explored are not reliable, and got their facts wrong. While NASA will often try to hide or spin any issues to make them seem less worrisome, it has almost never denied the existence of a serious problem, when it was revealed that such a problem had occurred.

I know to say this sounds paranoid, but this story also suggests this claim might be part of the growing effort within the federal bureaucracy and the press to attack SpaceX, because of its new irrational hostility to Elon Musk because he supports achievement and free speech.

At the same time, SpaceX has recently had to discard and replace a Dragon heat shield planned for a future mission because of discovered “manufacturing defect” during normal preflight testing. This confirmed story, combined with the unconfirmed and questionable story above, suggests SpaceX needs to take a closer look at the Dragon heat shield design.

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A spinning heat shield to lower their cost and weight

5:44 pm

Link here. Key quote:

Made of a flexible, strong and heat-resistant material that folds down when not in use, his shield automatically starts spinning like a samara-type tree seed when exposed to the onrush of air that a spacecraft would experience when dropping through a planet’s atmosphere.

As it spins, centrifugal force causes its skirt-like sides to flare out and stiffen. This creates the drag needed to help slow the descent, while also providing a large protective surface for the dissipation of heat. No additional machinery, other than the shield itself, is required for its deployment.

“Since this prototype is lightweight and flexible enough for use on smaller satellites, research could be made easier and cheaper,” says Wu. “The heat shield would also help save cost in recovery missions, as its high induced drag reduces the amount of fuel burned upon re-entry.”

More details here. Very clever. It needs to be tested to see if it can work.

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Orion heat shield redesigned before its launch?

9:59 am

Even before Orion’s first flight next month to test its heat shield, engineers are proposing a major change in the shield’s design and manufacture.

The Orion heat shield’s titanium skeleton and carbon fiber skin was fabricated by Lockheed Martin — the craft’s prime contractor — in Colorado. The skeleton was shipped to Textron Defense Systems in Massachusetts for installation of a fiberglass-phenolic honeycomb structure. More than 330,000 individual cells make up the honeycomb, and Textron technicians — using a special dispensing gun — filled the cells by hand with a material called Avcoat. The Avcoat insulation is supposed to ablate away during the Orion spacecraft’s re-entry, protecting the underlying structure from searing temperatures. The Apollo moon capsule used the same type of manually-applied material for its heat shield, and it worked so well Lockheed Martin and NASA decided to dust off the design.

Engineers scaled up the heat shield for the Orion crew capsule, which is about four feet wider at its base than the Apollo command module. “That’s what worked for Apollo, and that’s what we’ll work with for this mission,” Bray said, referring to the EFT-1 launch in December.

But a review of the heat shield on the Orion spacecraft set for launch Dec. 4 revealed the Avcoat was slightly more uneven than expected, according to Jim Bray, crew module director at Lockheed Martin, Orion’s prime contractor.

It also appears that it is too expensive to build the shield by hand, as it was done during Apollo. Instead, they intend to build future heat shields as single blocks assembled not by hand but by machine.

This is another example of why SLS/Orion is an incredible money black hole. What is the point of next month’s test flight of the heat shield if the shield they are testing is not going to be used on future flights?

Meanwhile, the press (apparently ignorant and uninformed about this subject and brainwashed by a NASA Orion press event) is filled with numerous stories claiming that this test flight is NASA’s first step to getting to Mars. What hogwash.

I especially like this quote from the space.com article:

On Dec. 4, NASA officials are expected to launch the Orion spacecraft on its first test flight, putting the capsule through its paces in space before it splashes down in the Pacific Ocean. The goal of the flight is to see how some key Orion systems — like its huge heat shield and parachutes — work before launching humans into deep space sometime in the future. [emphasis mine]

Yet, most of the heat shield test data obtained by this test flight will be worthless and inapplicable to future Orion capsules. In other words, this test flight is, as I said, hogwash, a public relations stunt to sell Orion to Congress and to uneducated reporters. It is also an enormous waste of taxpayer money and the limited resources NASA has.

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