Category: Space

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NASA’s “Snoopy” Award: Honoring the Heroes Behind the Scenes

When we think of space travel, we often think of astronauts—those brave individuals who venture into the unknown. However, the success of any space mission relies heavily on the countless unsung heroes working tirelessly behind the scenes. NASA, America’s premier space agency, has found a unique way to honor these individuals: the Silver Snoopy award.

The Silver Snoopy award, named after the beloved character from the Peanuts comic strip, is a special honor bestowed upon NASA employees and contractors who have made significant contributions to human flight safety or mission success. The award represents the astronauts’ personal recognition of excellence and is presented at the recipient’s workplace, with their coworkers present.

But why Snoopy? The choice of Snoopy as the mascot for the award has an interesting backstory. After the Mercury and Gemini projects, NASA wanted to create a greater awareness among its employees about the impact they had on flight safety and mission success. They needed a symbol that would be widely recognized and loved by the public.

Enter Al Chop, the director of the public affairs office for the Manned Spacecraft Center, who suggested using Snoopy, the adventurous beagle from Charles M. Schulz’s comic strip “Peanuts.” Schulz, a staunch supporter of the U.S. space program, loved the idea and even drew the image that the award pin is based on, at no cost to NASA.

The Silver Snoopy award isn’t just a certificate or a handshake. It includes a sterling silver “Silver Snoopy” lapel pin that has flown on a NASA mission, a commendation letter, and a signed, framed Silver Snoopy certificate. Also, Snoopy decals and posters are handed out to the honored individual.

But how does one earn such an honor? The criteria for consideration are quite extensive. An employee or contractor must contribute significantly beyond their normal work requirements to the development and implementation of human spaceflight programs, ensuring quality and safety. This could mean achieving specific goals that have a significant impact on a particular human spaceflight program or contributing to major cost savings. The employee could also have been instrumental in developing modifications that increase reliability, efficiency, or performance, or in developing a beneficial process improvement of significant magnitude.

The Silver Snoopy award has been a part of NASA’s tradition since 1968, when it was first awarded to some of the crew who worked on the LTA-8 project, a test version of what would become the lunar module. Since then, almost fifteen thousand people have been awarded a Silver Snoopy. However, the award is limited to no more than 1% of eligible recipients, and an individual can only receive the Silver Snoopy award once in their lifetime.

The Silver Snoopy award has a cultural impact beyond NASA’s walls. The pins have become collectibles, often fetching more than $1,000 on eBay. Adding to their appeal is the claim that each pin has been to space and back before it is awarded.

The legacy of the Silver Snoopy award was further cemented when a five-foot-tall statue of Snoopy in a spacesuit was erected outside of the Kennedy Space Center in 2009 to commemorate the 40th anniversary of Snoopy’s role in the Apollo 10 mission. Each time a Silver Snoopy is awarded, it reaffirms the role of the beloved cartoon dog and the unsung heroes in NASA’s space program.

From engineers to safety inspectors, from scientists to support staff—each recipient of the Silver Snoopy award plays an integral role in the success of our journey into space. The next time you look at the night sky and marvel at the wonders of space exploration, remember that there are countless Silver Snoopy recipients who have helped make those marvels possible.

In closing, Charles M. Schulz’s son Craig was once quoted as saying that his father was thrilled to work with the space program. The elder Schulz drew an original sketch of Snoopy in a space suit, complete with helmet, scarf, and little gearbox, and from this drawing, the Silver Snoopy award was cast. Today, the award continues to honor those who work tirelessly behind the scenes, ensuring the safety and success of each space mission.

Indeed, the Silver Snoopy award is a symbol of the collective human effort and ingenuity that makes space exploration possible. It serves as a reminder that every small step on Earth enables giant leaps in space.

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Rocket Engines, Acoustics, and the Resonance of Launch

The realm of rocket science, while primarily governed by mathematical equations and physics principles, is also deeply intertwined with the more nuanced domain of acoustics. It is not only the intense heat and force of the rocket exhaust that can cause potential damage during a launch; the powerful vibrations produced by the noise can also contribute to destructive outcomes. This phenomenon, the destructive power of sound, echoes the biblical story of the trumpets of Jericho, where the walls of the city were said to have tumbled down due to the resonance of the sound.

The launch of the SpaceX Starship on April 20, 2023, provides an illustrative example of this phenomenon. SpaceX’s Starship, the most powerful rocket ever built, conducted its first-ever fully stacked test flight on that day. However, upon its liftoff, a scene of wreckage emerged: the rocket’s 33 first-stage Raptor engines blew out a crater beneath the orbital launch mount, causing significant damage to the concrete pad and nearby infrastructure.

The damage was not solely attributable to the exhaust plume from the rocket engines. Instead, a significant factor was the lack of a flame trench, a structure designed to deflect plume exhaust away from the pad during liftoff. Flame trenches, which are common features of launch pads for powerful rockets, redirect the energy of the exhaust plume and thus mitigate the direct impact on the pad. But there is an additional, less obvious, factor in play – the acoustic vibrations generated by the rocket engines.

The Starship’s first-stage Raptors produce about 16.5 million pounds of thrust when firing at full capacity. This incredible force generates not only a physical push against the launch pad but also a cacophonous roar of sound. When this sound hits the concrete and other materials in the vicinity, it creates a vibrational response in those materials. These vibrations can cause the materials to resonate, and if the resonance reaches a high enough level, the materials can crack or even shatter.

Elon Musk, the founder of SpaceX, acknowledged the potential impact of the acoustics of launch. In a tweet after the launch, he suggested that the force of the engines when they throttled up may have shattered the concrete, rather than simply eroding it. This suggests that the acoustic vibrations from the engines may have contributed to the damage.

This destructive potential of sound brings to mind the biblical story of the trumpets of Jericho. According to the story in the Book of Joshua, the Israelites were instructed to march around the city once a day for six days, and on the seventh day, they marched around the city seven times. On the seventh lap, the priests blew their trumpets, the people shouted, and the walls of Jericho fell down flat. This story has often been interpreted to suggest that the walls were brought down by the sound from the trumpets, an idea that resonates with the modern understanding of acoustic resonance and its destructive potential.

The tale of Jericho and the recent Starship launch serve as powerful reminders of the interconnectedness of science and history, and of the hidden power of sound. Both events underscore the importance of considering not just the overtly visible forces at work in any situation, but also the more subtle, hidden factors, such as the acoustics of launch in rocket science.

As SpaceX and other space agencies continue to push the boundaries of rocket science, understanding and addressing these acoustic challenges will be crucial to ensuring successful and safe launches. After the Starship incident, Musk indicated that SpaceX was already developing a massive water-cooled steel plate to provide protection to the orbital launch mount, suggesting that the company is actively working on solutions to these challenges.

In the end, the story of the SpaceX Starship launch serves as both a cautionary tale about the power of sound and a testament to the potential of human ingenuity to overcome such challenges. The same science that explains the destructive potential of sound also provides the tools to mitigate its effects, demonstrating that with knowledge and innovation, we can turn potential obstacles into opportunities for progress.

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Calculating the Ideal Size of a Rocket Engine and the Decision to Combine Multiple Engines

Designing a rocket requires careful consideration of a number of variables, including the size and number of engines. So, how does one calculate the ideal size of a rocket engine and when does it make sense to combine several engines? Let’s delve into these fascinating aspects of rocket design.

Calculating the Ideal Size of a Rocket Engine

The performance of a rocket engine is typically evaluated by its thrust. Calculating the thrust of a rocket engine involves several variables including the mass flow rate through the engine, the exit velocity of the exhaust, and the pressure at the nozzle exit. The mass flow rate, in particular, is determined by the throat area of the nozzle, the smallest cross-sectional area of the nozzle.

The mass flow rate (m dot) is given by the formula

m . = A * p t T t γ R ( γ + 1 2 ) – γ + 1 2 ( γ – 1 )

The area ratio from the throat to the exit (Ae) sets the exit Mach number. The formula for the area ratio is

A e A * = ( γ + 1 2 ) – γ + 1 2 ( γ – 1 ) ( 1 + γ – 1 2 M e 2 ) M e γ + 1 2 ( γ – 1 )

Once we have the exit Mach number, we can calculate the exit pressure (pe) and exit temperature (Te) using the isentropic relations at the nozzle exit. The formulas for the exit pressure and temperature are

p e p t = ( 1 + γ – 1 2 M e 2 ) – 1 T e T t = ( 1 + γ – 1 2 M e 2 ) – γ γ – 1

Knowing the exit temperature, we can calculate the exit velocity (Ve) using the equation for the speed of sound and the definition of the Mach number. The formula for the exit velocity is

V e = M e γ R T e

Finally, we can calculate the thrust (F) of the rocket using the generalized thrust equation, which accounts for the fact that the exit pressure is only equal to free stream pressure at some design condition. The formula for the thrust is

F = m . V e + ( p e – p 0 ) A e

When to Combine Multiple Engines

Adding more engines or scaling up the size of existing engines are both valid ways of increasing thrust. However, the decision to use one approach over the other involves a careful balancing act.

On one hand, using a single large engine can lead to unstable exhausts where the combustion products ‘stick’ to one side of the nozzle, to a first degree of approximation similar to how a shower head when not turned on fully will run in a single stream rather than many small jets. The Rocketdyne F-1 engine used on the Saturn V is often considered the biggest practical size of engine. The Saturn V used 5 such engines, which meant that if one were to fail, there’d be very little in the way of backup.

On the other hand, using many smaller engines, while solving the problem of having a backup, presents its own set of challenges. The more engines you have, the higher the chances that having one fail catastrophically will result in the destruction of the entire craft. The plumbing alone can be a logistical nightmare to solve, as demonstrated by the N-1 rocket, which used 30 smaller engines in its first stage and flew four times, exploding on each occasion.

Moreover, it’s important to note that thrust is close to but not quite additive when multiple engines are involved. Plume-plume interactions can result in total thrust being slightly less than the sum of the thrusts from the individual engines.

Additionally, when multiple engines are used, the engines’ thrust can be vectored in different directions. However, the thrust available for acceleration of the spacecraft is reduced by the factor cos(θ), commonly referred to as “cosine losses”. This effect is due to the thrust not being aligned with the spacecraft’s center of mass, leading to a slight loss of linear acceleration.

Conclusion

Designing a rocket engine involves complex mathematical calculations and engineering considerations. Choosing the right size and number of engines is a balancing act, involving trade-offs between thrust, stability, complexity, and risk of catastrophic failure. The ideal solution often lies somewhere in between the extremes of a single large engine and many smaller ones.