NASA’s Remembrance:

This time of year serves to remind the human race that there is nothing routine about space flight, with three tragic anniversaries – Apollo 1, Challenger, and Columbia – all falling within five calendar days of each other early into each new year.

While the accidents, their causes, and the drive to mitigate repeat disasters are all well documented, the reminder – marked by NASA’s Day of Remembrance on the last Thursday of each January – serves to remind the current space program workforce that they have a job to do: to ensure no more names are added to the list of the fallen astronaut heroes.

KSC Director Bob Cabana knows what it’s like to put his life on the line for a mission into space. The retired USMC Colonel flew on four Space Shuttle missions and personally knew some of the lost heroes. He also was in charge of the spaceport that witnessed the final launches of the three surviving orbiters, each of which returned their crews home safely.

“Each year as I pause on our Day of Remembrance to honor those who made the ultimate sacrifice in our quest to explore space, I dedicate myself to ensuring that I do my very best to help prevent the loss of another life, whether as a crew member or in the line of duty supporting America’s space program,” noted Director Cabana in an address to the workforce.

“The business we are in is very demanding and terribly unforgiving of any mistakes we make.

“After laying the wreath, I took time to read the names on the mirror. They were some of my closest friends. They trusted us to do our best to protect them and keep them safe; they left loved ones behind who will always have an empty space that they once filled.”

KSC is currently transitioning to launch humans into space once again. As much as the new vehicles – ranging from commercial spaceships to NASA’s Orion capsule via the Space Launch System (SLS) - will be deemed “safer” than the Space Shuttle, it is unlikely the word “safe” will be taken for granted for decades to come, at least not when it involves sending crews uphill, riding on top of an explosion.

While the reminders this time of year are painful, the lessons from the three major disasters serve as motivation to ensure no more mistakes, to bring each crew back home safely and avoid another disaster which may result in the end of NASA in this risk adverse era.

“As we transition to a new future of commercial space operations and exploration beyond Earth, we cannot forget the lessons of our past,” added Director Cabana.

“They must be captured and passed on to ensure we do not repeat the same mistakes; that we do not take for granted our ability to launch humans into orbit; that just because we escaped harm in the past, it is no justification for success in the future; and that we have no hesitancy to share our concerns with anyone above or below us in the chain of command when it comes to the processing of critical space hardware that impacts the lives of our crew members, coworkers, and ourselves.

“We do amazing things at KSC, and we will continue to excel in the future because we have a culture of trust and integrity that binds us together. Let’s not lose that. Let’s not add any more names to the mirror. Let’s continue to do our best to ensure the health and safety of our crews and everyone else who works here at KSC.

“Thank you for your dedication to NASA, to KSC, and to human space exploration.”

Columbia’s loss remains the freshest in our minds. The beloved flagship which pioneered the Space Shuttle Program earned high praise from veteran commander John Young for her debut mission in 1981 and again from her inaugural pilot Bob Crippen who delivered a highly emotional tribute to Columbia during STS-107′s memorial speech – an amazing human tribute to a machine, one which is unlikely to be surpassed.
 
To vast amounts of people, both those who worked with the orbiters and those which followed their missions, the orbiters were living machines, almost differently sentient via their own personalities and quirks driven by a willingness to fight against the laws of physics to protect their crews.

Columbia had won that battle 27 times previous, before being mortally wounded during STS-107′s launch – a wound that sealed her fate during reentry 16 days later. Despite the gaping wound in her left wing, Columbia fought to the last during those final moments nine years ago today, as recognized by one of her engineers.
 
“Columbia’s lasting memorial in my eyes was her bravery that often gets over-looked,” noted one United Space Alliance engineer assigned to Columbia and who asked not to be named. “It was like she knew. I know that may sound strange – given she’s a machine, but I can’t – no matter how many times I look at the data – work out how she stayed mainly in one piece for so long, with her left wing terribly mis-shaped.
 
“Even with what we believe was – and I pray – an unconscious crew, and with her structure collapsing all around her, she still made multiple RCS (Reaction Control System) firings and rudder movements, fighting all the way to try and correct the drag. She should have been pulled over before she finally broke up, but she fought back, again and again.
 
“When I first got to see the data, I cried my eyes out. She was so brave to the end – I’m so proud of her and I’ll never forget her.”

Nine years later, Columbia continues to remind KSC’s current workforce of the need to work toward ensuring their future vehicles are in the best possible state for successfully launching and returning crews. Her remains continue to be held in a special room inside the very Vehicle Assembly Building (VAB) she and her surviving sisters were processed in for their missions.

However, Columbia’s AND Challenger’s spirits remain in space – and while it may take a stretch of the imagination, their memories were honored as they watched over each one of their three sisters as Discovery, Endeavour, and Atlantis each enjoyed their victory laps around the planet one final time before descending into the atmosphere to conclude their service lives with a successful reentry and landing.

Sadly, the future which Columbia strived to create is currently less than desirable. As the U.S. Space Agency struggles to find a proper sense of direction, the future of NASA and humanity’s crewed exploration of space remains locked in PowerPoints and developmental contracts.

While political bickering continues over how to budget the future, its impact on the relatively small percentage of funding for what remains an admired space program threatens to disrespect the very heroes honored at this time of year.

Such frustrations were brilliantly captured in an article written by former SSP manager Wayne Hale.

“Do you think that they (the fallen astronauts) would be proud of their country which can no longer send humans into space? Do you think they would be proud of their space agency which has no coherent plan to continue with exploration?” Mr. Hale wrote in on his site.

“Do you think that they would be proud of their government which has fallen into bickering so badly that even the half of 1 percent of the federal budget that used to enable the future has been significantly reduced?  Or do you think that they would be proud of a commercial sector that is long on PR and short on delivering new commercial spacecraft?”
 
A proud nation such as the United States needs to honor its heroes and provide the inspiration of the next generation to step up to the plate to become part of the legacy and push forward humanity’s future in space.

*Discuss this article here*

To read about the orbiters -  from birth, processing, every single mission, through to retirement, click here for the links:
http://forum.nasaspaceflight.com/index.php?topic=25837.0

(Images: NASA, L2, Associated Press).

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At the same time, the Shuttle Program has taught NASA and the space community the limits and specifications of the space vehicle’s systems. While some of these lessons have been learned through non-lethal failures/anomalies of Shuttle systems (such as the Flow Control Valve failure and resolution last year), two of the biggest lessons from the Space Shuttle Program were learned through the loss of orbiters Challenger and Columbia and their respective crews.

Challenger: O-rings, Field Joints, and Heaters:

The storied nature of the events leading up to the disintegration of the orbiter Challenger and the STS-51L stack on January 28, 1986 is one that will forever remain in the forethought of those in the Space Shuttle Program.

Nonetheless, while the reasons behind the disaster are remember to this day, it is important to remember the changes to the Solid Rocket Booster O-rings and field joints that came about as a result of the Rogers Commission investigation.

During the Rogers Commission hearings in 1986, Richard Feynman famously placed a small O-ring into a glass of ice water. When he removed the O-ring from the glass, he shocked many people by breaking the O-ring with little effort.

While this demonstration served as a visual representation of the brittle nature of the O-rings when exposed to cold temperatures, the display also served the engineering and physics communities in their understanding of the chemical composition of the O-rings.

By breaking the O-ring with ease, Feynman showed the inability of the FKM (Fluoroelastomer) component of the O-rings to maintain pliability in cold temperatures. This failure showed that when the O-rings were cooled below their Tg (glass transition temperature), they lost their elasticity – thereby eliminating their ability to flex and seal the joint casings of the SRBs during ignition and flight.

As the Rogers Commission determined, once the SRB O-rings are cooled near but not beyond their Tg limit, they became compressed and require a “longer than normal amount of time to return to their original shape” (in the case of Challenger, a circular shape with enough pliability to seal any gaps created from the flexing of the SRB cases during ignition and flight).

Since the temperatures at Challenger’s launch pad dipped well into the 20s (degrees F) the night before liftoff, the O-rings lost their pliability. As the temperatures on January 28 rose above freezing levels, a majority of the O-rings regained enough pliability to sufficiently seal the joint casing at SRB ignition.

Furthermore, while the ambient temperature at the time of Challenger’s launch was within Launch Commit Criteria guidelines, the temperature of the O-rings remained well below the ambient air temperature.

As a result, two of the O-rings on the Right Hand SRB did not regain enough pliability and failed across 70 degrees of arc at the moment of SRB ignition at the aft field joint at a circumferential point near the aft ET/SRB attach strut.

A complete blow-through of the SRB propellant flame was prevented in the early stages of Challenger’s flight due to aluminum oxides from burned solid propellant that became lodged within the secondary O-ring, thereby creating a temporary seal of the field joint.

Abnormally strong wind sheer encountered between T+37 seconds and T+64 seconds dislodged the temporary O-ring-like seal and allowed a hot gas penetration through the SRB field joint. The slipstream around the shuttle stack diverted the escaping SRB flame plume onto the External Tank and SRB/ET attach strut.

At T+64.66 seconds, the plume impingement on the ET weakened the structural integrity of the LH2 (Liquid Hydrogen) portion of the tank to a point permitting an LH2 leak. Within two seconds, pressure in the LH2 tank began dropping.

A T+72.284 seconds, the plume burned through the Right Hand SRB/ET attach bolt, severing the strut and allowing the SRB to rotate around its forward attach strut and causing a sharp, lateral acceleration to the right.

The aft dome of the External Tank’s LH2 tank failed at T+73.124 seconds, resulting in a massive propulsive force that pushed the LH2 tank into the LO2 (Liquid Oxygen) tank. At roughly the same time, the Right Hand SRB completed its rotation forward and struck the Inter-tank region of the ET.

Structural failure and breakup of the Challenger/51-L stack began almost immediately. Contrary to popular opinion and initial reports, the Challenger stack did not explode. A majority of the External Tank disintegrated from the loss of the structural integrity and the burning of LH2 and LO2 while the Challenger orbiter was forced from its ‘correct’ attitude in relation to the local slipstream and torn apart by divergent aerodynamic forces in excess of 20g — four times the maximum structural limit of the orbiter.

Following the loss of Challenger, NASA spent 2½ years upgrading the shuttle’s safety systems, including a redesign of the SRB field joint to include the addition of a third O-ring, the inclusion of a new, internal metal latch, and a redesign of insulation. These enhancements were designed to fortify the ability of the O-rings and fields joints to prevent hot gas penetration through the SRB joints.

Furthermore, electric heaters were installed into each joint. These heaters maintain O-ring temperatures during periods of cold ambient temperature. In this manner, the O-rings remain pliable and retain their ability to form a complete seal of the SRB joints.

These heaters remain a vital part of the SRB system to this day and are activated whenever the ambient temperature drops below 50-degrees F.

Furthermore, today’s Weather Launch Commit Criteria state: “Prior to external tank propellant loading, tanking will not begin if: a. The 24-hour average temperature has been below 41 degrees or b. The temperature has fallen below 33 degrees at anytime during the previous 24 hours.”

Moreover, “After tanking begins, the countdown shall not be continued nor the shuttle launched if: a.) The temperature exceeds 99 degrees for more than 30 consecutive minutes or b.) The temperature is lower than the prescribed minimum value for longer than 30 minutes unless sun angle, wind, temperature and relative humidity conditions permit recovery.”

This prescribed minimum value is determined by a 5-minute average of temperature, wind, and humidity levels. The prescribed minimum value temperature consideration becomes valid when the ambient temperature reaches 48-degrees F.

As a result, the lowest acceptable ambient temperature – with wind speed and ambient humidity factored in – is anywhere between 48-degrees and 36-degrees F.

This table can also be used to “determine when conditions are again acceptable for launch if parameters have been out of limits for 30 minutes or less. If longer than 30 minutes, a mathematical recovery formula of the environmental conditions is used to determine if a return to acceptable parameters has been achieved. Launch conditions have been reached if the formula reaches a positive value.”

Since the redesign of the SRB joints, only one serious O-ring anomaly has occurred. On STS-71 (June 1995), “evidence that hot exhaust gases had strayed dangerously within the booster nozzle” was discovered during post-flight inspections.

After discovery of this issue, Endeavour’s STS-69 mission was delayed indefinitely to allow NASA engineers as much time as necessary to investigate the failure and correct the problem.

Repairs to the O-ring nozzle seals on the STS-69 stack took place at the launch pad and involved “vacuum back-fill operations around the nozzle seals” and the installation of nozzle plugs.

STS-69 launched successfully on September 7, 1995. Post-flight SRB inspections revealed nominal performance of the O-rings around the nozzle seals.

To this day, NASA continues to closely monitor all O-ring and SRB field joint conditions pre- and post-launch. The addition of new thermal cord barriers to the SRB field joints along with the ongoing replacement of O-ring materials to increase the resiliency and design of the O-rings serves as the best demonstration of NASA’s commitment to SRB design and safety following the lessons learned for from the 51-L accident.

Columbia – Like losing a family member:

Lessons learned from the loss of Columbia in 2003 have also played a major role in improving the shuttle’s safety record.

The vehicle and her seven member crew were lost after a liberated piece of External Tank’s insulating foam impacted and breached a RCC (Reinforced Carbon Carbon) panel on Columbia’s left wing during the January 16th launch, Columbia stood no chance of surviving the unforgiving environment of re-entry on February 1.

While vast improvements have been made to the mitigation of foam releases from the ET during ascent are well documented, additional safety protocols were included in the post-Return To Flight “NASA Culture”, such as “Time Outs” – where any engineer can stop work on shuttle hardware if he/she seems anything they aren’t happy with – have aided the safety of the remaining fleet.

“We have a very strong timeout policy on the floor,” noted KSC Launch Director Mike Leinbach. “If one of the processing guys seems something wrong, they’ll call a time out, we’ll stand down and talk about it – and that’s heralded throughout the program. It’s an amazing program and it works well.

“The thing that really makes this all come together are the people that process these vehicles. I’m extremely proud of each and every one of them, and happy to represent them.

Many of these engineers are faced with the final year of working in the space program, as the shuttle comes to a close. However, their dedication to the vehicles is obvious, with the orbiters treated as beloved vehicles to such an extent Mr Leinbach noted it felt like losing a member of the family when Columbia was destroyed during re-entry.

“We couldn’t do all this work if we didn’t enjoy it and it’s is the love of the people doing the work. It’s an amazing amount of work, some of it is very repetitive – but you’d be amazed how often a repetitive job becomes a job of love by the people themselves.

“‘Yeah, I’ve torqued this bolt down on this ship 100 times, but by God I’m going to do bolt 101 the same way.’,” added Mr Leinbach as an example. “You have to see and feel it to understand, I wish I could explain it – just an amazing team to see at work.

“It comes from within and one of the times that I like to reflect on – even though its sad – is the Columbia accident. We lost seven astronauts and that was awful, just devastating, but we also lost an orbiter.

“It’s hard to explain to people but when we lost Columbia it was like losing a family member. It’s almost that deep when you work on these machines day in and day out.”

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A liberated piece of External Tank’s insulating foam impacted and breached a RCC (Reinforced Carbon Carbon) panel on Columbia’s left wing during the January 16th launch, Columbia had no chance of surviving the unforgiving environment of re-entry.

Despite some voices – mostly those opposed to extending the shuttle program due to their Ares-based interests – citing scary loss of vehicle probability numbers for the remaining flights, the space shuttle is far safer than before STS-107.

Extensive modifications to the External Tanks have seen a huge reduction in foam liberation, with the 2008 missions recording four of the cleanest flights in the shuttle programs history, resulting in no damage to the orbiter’s Thermal Protection System (TPS).

Since Return To Flight (RTF), no orbiter has suffered TPS damage that has even come close to calling up the additional backup of LON (Launch On Need) – which utilizes a plan to call up the next scheduled shuttle on a rescue mission.

Knowing an orbiter hasn’t suffered any damage has proved to be one of the key RTF improvements, thanks to multiple checks throughout the mission.

Those methods involve hardware and process improvements, such as the WLEIDS (Wing Leading Edge Impact Detection System), used to ‘feel’ for any impact threats to the orbiter RCC/TPS that may have been missed by the multitude of imagery and radar tracking techniques that follow the shuttle during her ride uphill.

Flight Day 2 now involves the use of another RTF capability, the Orbiter Boom Sensor System (OBSS), used to check critical areas of the orbiter TPS, prior to Flight Day 3′s RPM (Rbar Pitch Maneuver) photography – resulting in thousands of images of every inch of the vehicle, checked over by the Damage Assessment Team (DAT) on the ground.

Post undocking Late Inspections again utilize the OBSS for a final check of the TPS, ahead of clearance for re-entry, with post flight inspections and reviews ensuring any lessons learned from the previous flight are taken onboard for the upcoming mission. The resulting details, even for the slightest anomaly, are nothing short of impressive.

Unfortunately, the shuttle is a hugely complex vehicle, and is by its very design “unsafe”, but so is space flight in general. Protecting against the threats, to the greatest possible extent, is – without any doubt – being carried out by the engineers and managers tasked with caring for the vehicles and their crews.

Examples can be seen almost on a daily basis, where dissent is welcomed and problems are discussed, as opposed to hidden or shouted down, an allegation of “bad culture” cited by the investigations into the losses of Challenger and Columbia.

Any engineer can now call a “Time Out” and managers can call for a “Safety Stand Down”, should there be the slightest concern about a process being carried out on the flight hardware, an example of which occurred just last week.

“Had instances in operations over last couple of weeks that appear to have a common element – little errors on the part of techs,” noted a recent Shuttle Stand-Up/Integration Report on L2, relating to a small issue with the processing of the Reusable Solid Rocket Motors (RSRM).

“In an effort to refocus people and take a time out and think about that, they had a Safety Stand Down Thursday morning.”

“Leadership went out into various areas and talked to folks about some of those instances; made a plea for them to take a deep breath and focus on the task at hand. Think this was a positive thing.”

Examples of the intense process of ensuring the next mission is safe to proceed towards its launch date can be seen during the FRR (Flight Readiness Review) period, which results in literally 1000s of pages of documentation on each and every aspect of the vehicle and her mission.

The importance of the FRR process, and its ability – more so insistence – on full and frank communication, can be seen in a rallying call from Mission Management Team (MMT) co-chair Leroy Cain, who – alongside shuttle manager John Shannon – are carrying on the impressive management of the program, since taking over from former SSP manager Wayne Hale.

“Had a good (SSP) FRR last week. We know the work we have going forward, and have some new work probably that we weren’t aware of at the FRR,” noted Mr Cain on last week’s Stand-Up report. “It is going to be a very busy week to get ready for the (Agency) FRR next week in Florida.

“Please work very hard to that end (preparing their documentation for the FRR). I think the team is doing great; communication is really, really good. From the few items we have going on, I’m seeing great communication up and down, and back and forth across the teams. We really need to continue that.”

Mr Cain went on to note to the extensive shuttle team that he understands there is a lot going on with the Agency, with a new administrator still to be chosen, the possibility of the shuttle program being extended, doubts over the future of the Constellation program – and asked the team to continue to stay focused on the most important upcoming event – STS-119.

“Outside the work we are doing here, as it pertains to getting ready for STS-119/15A, there is a whole lot of distraction outside of our SSP world and ISS world that is easy for us to get mired down in,” he added. “But we have one mission in front of us right now that we need to keep focused on.

“I’m very happy to say that I see the team has our focus set in the right place, the right way. Please continue that; please continue to emphasize that with your troops.

“We must fly the best mission we can on STS-119. That is our focus right now; that is the only thing that matters right now to the team. Everything else will sort itself out over time. That is our number one priority.

“So please stay focused, keep doing great work, keep talking to each other, and let’s have a good week.”

While the risk of losing another vehicle is sometimes in the lap of the Gods, there is no doubt the teams are doing their absolute best to ensure Columbia’s legacy is one of safe and successful missions until the fleet is retired, and beyond.

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