Moon 2024 - Blog Posts

Rockets, Racecars, and the Physics of Going Fast

When our Space Launch System (SLS) rocket launches the Artemis missions to the Moon, it can have a top speed of more than six miles per second. Rockets and racecars are designed with speed in mind to accomplish their missions—but there’s more to speed than just engines and fuel. Learn more about the physics of going fast:

Take a look under the hood, so to speak, of our SLS mega Moon rocket and you’ll find that each of its four RS-25 engines have high-pressure turbopumps that generate a combined 94,400 horsepower per engine. All that horsepower creates more than 2 million pounds of thrust to help launch our four Artemis astronauts inside the Orion spacecraft beyond Earth orbit and onward to the Moon. How does that horsepower compare to a racecar? World champion racecars can generate more than 1,000 horsepower as they speed around the track.

As these vehicles start their engines, a series of special machinery is moving and grooving inside those engines. Turbo engines in racecars work at up to 15,000 rotations per minute, aka rpm. The turbopumps on the RS-25 engines rotate at a staggering 37,000 rpm. SLS’s RS-25 engines will burn for approximately eight minutes, while racecar engines generally run for 1 ½-3 hours during a race.

To use that power effectively, both rockets and racecars are designed to slice through the air as efficiently as possible.

While rockets want to eliminate as much drag as possible, racecars carefully use the air they’re slicing through to keep them pinned to the track and speed around corners faster. This phenomenon is called downforce.

Steering these mighty machines is a delicate process that involves complex mechanics.

Most racecars use a rack-and-pinion system to convert the turn of a steering wheel to precisely point the front tires in the right direction. While SLS doesn’t have a steering wheel, its powerful engines and solid rocket boosters do have nozzles that gimbal, or move, to better direct the force of the thrust during launch and flight.

Racecar drivers and astronauts are laser focused, keeping their sights set on the destination. Pit crews and launch control teams both analyze data from numerous sensors and computers to guide them to the finish line. In the case of our mighty SLS rocket, its 212-foot-tall core stage has nearly 1,000 sensors to help fly, track, and guide the rocket on the right trajectory and at the right speed. That same data is relayed to launch teams on the ground in real time. Like SLS, world-champion racecars use hundreds of sensors to help drivers and teams manage the race and perform at peak levels.

Knowing how to best use, manage, and battle the physics of going fast, is critical in that final lap. You can learn more about rockets and racecars here.

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NASA Photographers Share Their Favorite Photos of the SLS Moon Rocket

NASA’s Space Launch System (SLS) rocket is on the launch pad at NASA’s Kennedy Space Center in Florida and in final preparations for the Artemis I mission to the Moon. Now that our Moon rocket is almost ready for its debut flight, we wanted to take a look back at some of the most liked photographs of our SLS rocket coming together over the years.

We asked NASA photographers to share their favorite photos of the SLS rocket for Artemis I at different phases of testing, manufacturing, and assembly. Here are their stories behind the photos:

“On this day in March 2018, crews at NASA’s Marshall Space Flight Center in Huntsville, Alabama, transported the intertank structural test article off NASA’s Pegasus barge to the Load Test Annex test facility for qualification testing.” —Emmett Given, photographer, NASA’s Marshall Space Flight Center

“This is the liquid oxygen tank structural test article as it was moved from the Pegasus barge to the West Test Area at our Marshall Space Flight Center on July 9, 2019. The tank, which is structurally identical to its flight version, was subsequently placed in the test stand for structural testing several days later. I remember it being a blazing hot day!” —Fred Deaton, photographer, NASA’s Marshall Space Flight Center

“The large components of the SLS rocket’s core stage can make you forget that there are many hands-on tasks required to assemble a rocket, too. During the mating of the liquid hydrogen tank to the forward section of the rocket’s 212-foot-tall core stage in May 2019, technicians fastened 360 bolts to the circumference of the rocket. Images like this remind me of all the small parts that have to be installed with care, expertise, and precision to create one huge Moon rocket. Getting in close to capture the teammates that work tirelessly to make Artemis a success is one of the best parts of my job.” —Eric Bordelon, photographer, NASA’s Michoud Assembly Facility

“An incredible amount of precision goes into building a rocket, including making sure that each of our SLS rocket’s four RS-25 engines is aligned and integrated into the core stage correctly. In this image from October 2019, I attempted to illustrate the teamwork and communication happening as technicians at NASA’s Michoud Assembly Facility in New Orleans do their part to help land the first woman and the first person of color on the Moon through the Artemis missions. It’s rare to see the inside of a rocket – not as much for the NASA and Boeing engineers who manufacture and assemble a rocket stage!” —Jared Lyons, photographer, NASA’s Michoud Assembly Facility

“When the fully assembled and completed core stage left the Michoud factory in January 2020, employees took a “family photo” to mark the moment. Crews transported the flight hardware to NASA’s Pegasus barge on Jan. 8 in preparation for the core stage Green Run test series at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. When I look at this photo, I am reminded of all of the hard work and countless hours the Michoud team put forth to build this next-generation Moon rocket. I am honored to be part of this family and to photograph historic moments like this for the Artemis program.” —Steven Seipel, MAF multimedia team lead, NASA’s Michoud Assembly Facility

“This photo shows workers at Stennis prepare to lift the SLS core stage into the B-2 Test Stand for the SLS Green Run test series in the early morning hours of Jan. 22, 2020. I started shooting the lift operation around midnight. During a break in the action at about 5:30 a.m., I was driving my government vehicle to the SSC gas station to fuel up, when I saw the first light breaking in the East and knew it was going to be a nice sunrise. I turned around and hurried back to the test stand, sweating that I might run out of gas. Luckily, I didn’t run out and was lucky enough to catch a beautiful Mississippi sunrise in the background, too.” —Danny Nowlin, photographer, NASA’s Stennis Space Center

“I like the symmetry in the video as it pushes toward the launch vehicle stage adapter. Teams at NASA’s Marshall Space Flight Center in Huntsville, Alabama, loaded the cone-shaped piece of flight hardware onto our Pegasus barge in July 2020 for delivery to NASA’s Kennedy Space Center in Florida. The one-point perspective puts the launch vehicle stage adapter at the center of attention, but, if you pay attention to the edges, you can see people working. It gives a sense of scale. This was the first time I got to walk around Pegasus and meet the crew that transport the deep space rocket hardware, too.” —Sam Lott, videographer, SLS Program at Marshall Space Flight Center

“This was my first time photographing a test at our Stennis Space Center, and I wasn't sure what to expect. I have photographed big events like professional football games, but I wasn't prepared for the awesome power unleashed by the Space Launch System’s core stage and four RS-25 engines during the Green Run hot fire test. Watching the sound wave ripple across the tall grass toward us, feeling the shock wave of ignition throughout my whole body, seeing the smoke curling up into the blue sky with rainbows hanging from the plume; all of it was as unforgettable as watching a football player hoist a trophy into the air.” —Michael DeMocker, photographer, NASA’s Michoud Assembly Facility

“When our SLS Moon rocket launches the agency’s Artemis I mission to the Moon, 10 CubeSats, or small satellites, are hitching a ride inside the rocket’s Orion stage adapter (OSA). BioSentinel is one of those CubeSats. BioSentinel’s microfluidics card, designed at NASA’s Ames Research Center in California’s Silicon Valley, will be used to study the impact of interplanetary space radiation on yeast. To me, this photo is a great combination of the scientific importance of Artemis I and the human touch of more than 100 engineers and scientists who have dedicated themselves to the mission over the years.” —Dominic Hart, photographer, NASA’s Ames Research Center

“I was in the employee viewing area at Kennedy when the integrated SLS rocket and Orion spacecraft was rolled out to the launchpad for its wet dress rehearsal in March 2022. I really like this photo because the sun is shining on Artemis I like a spotlight. The giant doors of the Vehicle Assembly Building are the red curtain that opened up the stage -- and the spotlight is striking the SLS because it’s the star of the show making its way to the launchpad. I remember thinking how cool that NASA Worm logo looked as well, so I wanted to capture that. It was so big that I had to turn my camera sideways because the lens I had wasn’t big enough to capture the whole thing.” —Brandon Hancock, videographer, SLS Program at NASA’s Marshall Space Flight Center

“I made this image while SLS and Orion atop the mobile launcher were nearing the end of their four-mile trek to the pad on crawler-transporter 2 ahead of launch. Small groups of employees were filtering in and out of the parking lot by the pad gate to take in the sight of the rocket’s arrival. The “We Are Going!” banner affixed to the gate in the foreground bears the handwritten names of agency employees and contractors who have worked to get the rocket and spacecraft ready for the Artemis I flight test. As we enter the final days before launch, I am proud to have made my small contribution to documenting the historic rollout for this launch to the Moon.” —Joel Kowsky, photographer, NASA Headquarters

More Photo-worthy Moments to Come!

NASA photographers will be on the ground covering the Artemis I launch. As they do, we’ll continue to share their photos on our official NASA channels.

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Our Space Launch System Rocket’s “Green Run” Engine Testing By the Numbers

We continue to make progress toward the first launch of our Space Launch System (SLS) rocket for the Artemis I mission around the Moon. Engineers at NASA’s Stennis Space Center near Bay St. Louis, Mississippi are preparing for the last two tests of the eight-part SLS core stage Green Run test series.

The test campaign is one of the final milestones before our SLS rocket launches America’s Orion spacecraft to the Moon with the Artemis program. The SLS Green Run test campaign is a series of eight different tests designed to bring the entire rocket stage to life for the first time.

As our engineers and technicians prepare for the wet dress rehearsal and the SLS Green Run hot fire, here are some numbers to keep in mind:

212 Feet

The SLS rocket’s core stage is the largest rocket stage we have ever produced. From top to bottom of its four RS-25 engines, the rocket stage measures 212 feet.

35 Stories

For each of the Green Run tests, the SLS core stage is installed in the historic B-2 Test Stand at Stennis. The test stand was updated to accommodate the SLS rocket stage and is 35 stories tall – or almost 350 feet!

4 RS-25 Engines

All four RS-25 engines will operate simultaneously during the final Green Run Hot Fire. Fueled by the two propellant tanks, the cluster of engines will gimbal, or pivot, and fire for up to eight minutes just as if it were an actual Artemis launch to the Moon.

18 Miles

Our brawny SLS core stage is outfitted with three flight computers and special avionics systems that act as the “brains” of the rocket. It has 18 miles of cabling and more than 500 sensors and systems to help feed fuel and direct the four RS-25 engines.

733,000 Gallons

The stage has two huge propellant tanks that collectively hold 733,000 gallons of super-cooled liquid hydrogen and liquid oxygen. The stage weighs more than 2.3 million pounds when its fully fueled.

114 Tanker Trucks

It’ll take 114 trucks – 54 trucks carrying liquid hydrogen and 60 trucks carrying liquid oxygen – to provide fuel to the SLS core stage.

6 Propellant Barges

A series of barges will deliver the propellant from the trucks to the rocket stage installed in the test stand. Altogether, six propellant barges will send fuel through a special feed system and lines. The propellant initially will be used to chill the feed system and lines to the correct cryogenic temperature. The propellant then will flow from the barges to the B-2 Test Stand and on into the stage’s tanks.

100 Terabytes

All eight of the Green Run tests and check outs will produce more than 100 terabytes of collected data that engineers will use to certify the core stage design and help verify the stage is ready for launch.

For comparison, just one terabyte is the equivalent to 500 hours of movies, 200,000 five-minute songs, or 310,000 pictures!

32,500 holes

The B-2 Test Stand has a flame deflector that will direct the fire produced from the rocket’s engines away from the stage. Nearly 33,000 tiny, handmade holes dot the flame deflector. Why? All those minuscule holes play a huge role by directing constant streams of pressurized water to cool the hot engine exhaust.

One Epic First

When NASA conducts the SLS Green Run Hot Fire test at Stennis, it’ll be the first time that the SLS core stage operates just as it would on the launch pad. This test is just a preview of what’s to come for Artemis I!

The Space Launch System is the only rocket that can send NASA astronauts aboard NASA’s Orion spacecraft and supplies to the Moon in a single mission. The SLS core stage is a key part of the rocket that will send the first woman and the next man to the Moon through NASA’s Artemis program.

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What You Need to Know About Our Space Launch System (SLS) Rocket’s Green Run Test

The comprehensive test series called Green Run for our Space Launch System (SLS) rocket is underway at Stennis Space Center in Mississippi. 

During Green Run, the rocket’s massive, 212-foot-tall core stage — the same flight hardware that will help launch Artemis I to the Moon – will operate together for the first time. 

Here’s what you need to know about this top-to-bottom test series of our megarocket’s huge core:

The Meaning Behind the Name 

Why is it called Green Run? “Green” refers to the new, untested hardware (AKA the core stage), and “run” represents the succession of tests the core stage paces through. One by one, this series will bring together several “firsts” for the rocket stage as the flight hardware undergoes eight different tests. Each test is designed to gradually bring our rocket’s core stage and all its systems to life for the first time. 

So far, engineers have completed three of the series: the modal test, the avionics power-on, and the safety systems checkout. The safety systems are designed to end the test and shutdown systems automatically under undesirable conditions.

You can follow the progress of Green Run with this Green Run checklist infographic. Our team will be updating in real time as each Green Run test is completed.

Setting the Stage

The world’s tallest rocket stage is tested in an equally giant test stand.  We upgraded the B-2 Test Stand used for the Saturn V rocket stages during the Apollo Program and, later, for the Space Shuttle Program. Now, the B-2 Test Stand is customized for testing our SLS core stage. When all four core stage engines fire up, they can generate some serious heat. So, the B-2 Test Stand will use roughly 100,000 gallons of water every 18 seconds to protect the stand and the hardware.

Hot fire in 3, 2, 1…

Speaking of engines firing up, the core stage will really show what it is capable of during the grand finale of Green Run. The goal is for the entire core stage to operate as one for up to 8.5 minutes — and that includes an impressive firing of all four RS-25 engines simultaneously. Just like at launch, more than 733,000 gallons of liquid propellant will flow from the two propellant tanks through the fuel lines to feed the RS-25 engines.  When operating at sea level on the test stand, the cluster of four RS-25 engines will produce just over 1.6 million pounds of thrust – the same amount it will produce during the early phase of launch. During ascent, the core stage will produce a maximum thrust of over 2 million pounds.

Data, data, data

All the Green Run tests, check outs and the 100 terabytes of collected data certify the core stage design and help verify the stage is ready for launch. To put the sheer amount of data collected during Green Run into perspective, just one terabyte is the equivalent of roughly 500 hours of movies. Even the Library of Congress’s collection only amounts to a total of 15 terabytes!

Next stop: Kennedy

The next time our SLS rocket’s core stage fires up will be on the launch pad at Kennedy Space Center for the debut of the Artemis program. This inaugural SLS flight will be just the beginning of increasingly complex missions that will enable human exploration to the Moon and, ultimately, Mars.

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The Artemis Story: Where We Are Now and Where We’re Going

Using a sustainable architecture and sophisticated hardware unlike any other, the first woman and the next man will set foot on the surface of the Moon by 2024. Artemis I, the first mission of our powerful Space Launch System (SLS) rocket and Orion spacecraft, is an important step in reaching that goal.

As we close out 2019 and look forward to 2020, here’s where we stand in the Artemis story — and what to expect in 2020. 

Cranking Up The Heat on Orion

The Artemis I Orion spacecraft arrived at our Plum Brook Station in Sandusky, Ohio, on Tuesday, Nov. 26 for in-space environmental testing in preparation for Artemis I.

This four-month test campaign will subject the spacecraft, consisting of its crew module and European-built service module, to the vacuum, extreme temperatures (ranging from -250° to 300° F) and electromagnetic environment it will experience during the three-week journey around the Moon and back. The goal of testing is to confirm the spacecraft’s components and systems work properly under in-space conditions, while gathering data to ensure the spacecraft is fit for all subsequent Artemis missions to the Moon and beyond. This is the final critical step before the spacecraft is ready to be joined with the Space Launch System rocket for this first test flight in 2020!

Bringing Everyone Together

On Dec. 9, we welcomed members of the public to our Michoud Assembly Facility in New Orleans for #Artemis Day and to get an up-close look at the hardware that will help power our Artemis missions. The 43-acre facility has more than enough room for guests and the Artemis I, II, and III rocket hardware! NASA Administrator Jim Bridenstine formally unveiled the fully assembled core stage of our SLS rocket for the first Artemis mission to the Moon, then guests toured of the facility to see flight hardware for Artemis II and III. The full-day event — complete with two panel discussions and an exhibit hall — marked a milestone moment as we prepare for an exciting next phase in 2020.

Rolling On and Moving Out

Once engineers and technicians at Michoud complete functional testing on the Artemis I core stage, it will be rolled out of the Michoud factory and loaded onto our Pegasus barge for a very special delivery indeed. About this time last year, our Pegasus barge crew was delivering a test version of the liquid hydrogen tank from Michoud to NASA’s Marshall Space Flight Center in Huntsville for structural testing. This season, the Pegasus team will be transporting a much larger piece of hardware — the entire core stage — on a slightly shorter journey to the agency’s nearby Stennis Space Center near Bay St. Louis, Mississippi.

Special Delivery

Why Stennis, you ask? The giant core stage will be locked and loaded into the B2 Test Stand there for the landmark Green Run test series. During the test series, the entire stage, including its extensive avionics and flight software systems, will be tested in full. The series will culminate with a hot fire of all four RS-25 engines and will certify the complex stage “go for launch.” The next time the core stage and its four engines fire as one will be on the launchpad at NASA’s Kennedy Space Center in Florida.

Already Working on Artemis II

As Orion and SLS make progress toward the pad for Artemis I, employees at NASA centers and large and small companies across America are hard at work assembling and manufacturing flight hardware for Artemis II and beyond.  The second mission of SLS and Orion will be a test flight with astronauts aboard that will go around the Moon before returning home. Our work today will pave the way for a new generation of moonwalkers and Artemis explorers.

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