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Forum:	Mercury - Gemini - Apollo
Topic:	Liberty Bell 7: Static electricity and the hatch

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Your Reply: HTML is ON UBB Code is ON Smilies Legend	[QUOTE]Originally posted by Robert Pearlman: [B]Andy Saunders and George Leopold will discuss "How and Why Did Static Electricity — And Not Gus Grissom — Blow the Hatch on Liberty Bell 7?" during the next NASA History Virtual Talk on Aug. 25 at noon EDT. <BLOCKQUOTE>[i]The hatch blow on Liberty Bell 7, leading to the loss of the spacecraft and almost drowning astronaut Virgil I. "Gus" Grissom? Did Grissom deliberately or accidentally blow the hatch, or did some other technical or procedural deficiency contribute to the failure at the end of the otherwise flawless mission? After 60 years, new research and compelling evidence will be presented to provide what we believe is the most plausible scenario for what exactly happened on July 21, 1961.[/i]</BLOCKQUOTE> The meeting, to be <A HREF="https://teams.microsoft.com/dl/launcher/launcher.html?url=%2F_%23%2Fl%2Fmeetup-join%2F19%3Ameeting_MTI3N2MyNTktMmM2OC00MzUwLWIwZmYtNWZlYjc5OTBjZGEy%40thread.v2%2F0%3Fcontext%3D%257b%2522Tid%2522%253a%25227005d458-45be-48ae-8140-d43da96dd17b%2522%252c%2522Oid%2522%253a%2522906db907-6ff4-48b7-a98b-9c6e0ac8a41f%2522%257d%26anon%3Dtrue&type=meetup-join&dee plinkId=49e91724-e674-4589-b98a-0bef9e3122c7&directDl=true&msLaunch=true&enableMobilePage=true&suppressPrompt=true" target="AirLock">accessed through this link</a>, will be held via Microsoft Teams.[/B][/QUOTE]
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<table border=0 cellpadding=0 cellspacing=0 width="600"><TR><td bgcolor="#000000"><TABLE BORDER=0 cellpadding=4 border=0 cellspacing=1 WIDTH="100%"><TR bgcolor="#660000"><TD COLSPAN=2><CENTER><FONT SIZE="2" COLOR="#ffffff" FACE="sans-serif">T O P I C     R E V I E W</font></CENTER></TD></TR><TR bgcolor="#494949"><TD valign=top><FONT SIZE="2" FACE="sans-serif">Robert Pearlman</FONT></TD><TD><FONT SIZE="2" FACE="sans-serif">Author George Leopold ("Calculated Risk: The Supersonic Life and Times of Gus Grissom") and imaging specialist Andy Saunders ("Apollo Remastered") <A HREF="https://astronomy.com/news/2021/07/did-static-electricity-blow-the-hatch-of-liberty-bell-7" TARGET=_blank>published today</A> (July 21) — the 50th anniversary of the Mercury-Redstone 4 mission — new findings in the cause behind the early hatch jettison on Liberty Bell 7. <BLOCKQUOTE><I>...based on a frame-by-frame re-examination of the highest-quality transfer of the original recovery footage, kindly provided by archivist Stephen Slater. The digital imaging techniques we have applied to this film reveal details previously unavailable. They confirm the recollections of the person closest to Grissom's spacecraft at the critical moment: U.S. Marine Corps Lieutenant John Reinhard, who was situated at the side door of the prime recovery helicopter. Our enhanced footage has even jogged the memory of another eyewitness, U.S. Marine Corps Lieutenant James Lewis, pilot of the primary helicopter sent to recover Grissom and Liberty Bell 7. <P>Based on the available evidence, we conclude that electrostatic discharge generated during the ultimately unsuccessful attempt to recover Grissom's spacecraft most likely caused the premature detonation of the explosive hatch.</I></BLOCKQUOTE> As Tony Reichhardt summarizes for <A HREF="https://www.airspacemag.com/daily-planet/new-evidence-shows-gus-grissom-did-not-accidentally-sink-his-own-spacecraft-sixty-years-ago-180978240/" TARGET=_blank>Air & Space magazine</A>: <BLOCKQUOTE><I>Through careful enhancement of film footage shot during the rescue, and from certain key details Reinhard recalled from that morning, Saunders and Leopold now think they can reconstruct what really happened. Reinhard remembers seeing an electrical arc just as he touched the cutting tool to Liberty Bell 7's antenna — before the helicopter hooked on to the spacecraft to raise the hatch above water. That same electrical charge, conclude the authors, probably caused the hatch to blow.<P>And they've produced photographic proof. In enhanced frames from the film, just as the cutting tool touches the spacecraft, a small, dark object is seen jetting away from the capsule. It's very likely — though not absolutely certain — that this is the hatch, as shown in this short clip (Grissom appears in the video's initial poster frame, to show the location of the hatch).</I></BLOCKQUOTE> <center><iframe width="400" height="225" src="https://www.youtube.com/embed/Y2RqJTBX29E" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen>

Headshot

This sounds plausible, but then the question arises of why did not the door prematurely blow during Alan Shepard's recovery? Was there a fundamental design difference between the two hatches?

ejectr

Shepard had a mechanical latch that allowed him to open it from the inside and drop it into the ocean. No explosive bolts were used on MR 3.

Headshot

Thanks. I was totally unaware of that.

oly

The headline "New Evidence Shows That Gus Grissom Did Not Accidentally Sink His Own Spacecraft 60 Years Ago" indicates that previous evidence shows that Grissom sank the Mercury 4 capsule, which is not the case.

Additionally, the "enhanced" film footage fails to show any details that were not previously known. The smoke pointed out in the footage is a result of the explosive charges detonating, a requirement for the hatch to "blow," and there has never been an argument that the explosive charges did not fire. Film of the smoke from hatch charges firing can be seen here.

For static electricity generated by the rotorcraft to fire the charges, the charges would have to be susceptible to electrostatic discharge.

The capsule would have generated a huge electrostatic charge during launch or reentry. Why did this electrostatic charge not fire the hatch charges or many other explosive charges installed in the spacecraft during the flight?

Part of the helicopter recovery procedure is to cut the capsule whip antenna using shears, which would have created a path to electrostatically bond the helicopter to the capsule. Additionally, connecting the helicopter to the capsule cargo lift cable would complete an electrical discharge path, and dangling the winch cable in the ocean would create an additional discharge path.

I don't buy it.

Robert Pearlman

Andy Saunders and George Leopold will discuss "How and Why Did Static Electricity — And Not Gus Grissom — Blow the Hatch on Liberty Bell 7?" during the next NASA History Virtual Talk on Aug. 25 at noon EDT.

The hatch blow on Liberty Bell 7, leading to the loss of the spacecraft and almost drowning astronaut Virgil I. "Gus" Grissom? Did Grissom deliberately or accidentally blow the hatch, or did some other technical or procedural deficiency contribute to the failure at the end of the otherwise flawless mission? After 60 years, new research and compelling evidence will be presented to provide what we believe is the most plausible scenario for what exactly happened on July 21, 1961.

The meeting, to be accessed through this link, will be held via Microsoft Teams.

ejectr

I'm sure all are aware, Liberty Bell 7 was the first spacecraft with an explosive hatch to be lifted out of the water by a helicopter. It was also the first to ever use an explosive hatch.

oly

It may have been the first use of an “explosive” hatch on a spacecraft, but pyrotechnics were not new to the aerospace industry, they had been in used since 1945, and jet aircraft emergency egress systems had been using pyrotechnics to deploy canopies during the ejection cycle for some time.

The Mercury spacecraft has electrostatic protection designed into many systems, and has numerous pyrotechnic devices installed throughout design. Theoretically, the explosive charge initiator and the hatch explosive charge would be electrically bonded to the spacecraft structure, which should act as a faraday cage for electrostatic discharge caused by the recover helicopter, and any residual static charge gained during re-entry.

The post flight investigation covered the subject of an accidental activation of the initiator, and procedural changes introduced after the investigation resulted in no other Mercury spacecraft experiencing an uncommanded hatch "explosion" during recovery.

If Buzz Aldrin can unknowingly break a circuit breaker while moving about a stationary vehicle, the chance of something accidentally hitting the unsafe initiator as the capsule rides the waves does exist.

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