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By NASA
NASA Teams responsible for preparing and launching Artemis II at NASA’s Kennedy Space Center in Florida are set to begin a series of integrated tests to get ready for the mission. With the upper stage of the agency’s SLS (Space Launch System) integrated with other elements of the rocket, engineers are set to start the tests to confirm rocket and ground systems are working and communicating as planned.
While similar to the integrated testing campaign conducted for NASA’s uncrewed Artemis I test flight, engineers have added tests ahead of Artemis II to prepare for NASA’s first crewed flight under the Artemis campaign – an approximately 10-day journey by four astronauts around the Moon and back. The mission is another step toward missions on the lunar surface and helping the agency prepare for future astronaut missions to Mars.
Interface Verification Testing
Verifies the functionality and interoperability of interfaces across elements and systems. Teams will conduct this test from the firing room in the Launch Control Center and perform health and status checks of various systems and interfaces between the SLS core stage, the solid rocket boosters, and the ground systems. It will ensure different systems, including core stage engines and booster thrust control, work as planned. Teams also will perform the same series of tests with the interim cryogenic propulsion stage and Orion before conducting a final interface test with all segments.
Program Specific Engineering Test
Teams will conduct separate engineering tests for the core stage, rocket boosters, and upper stage following the interface verification tests for each part of the rocket.
End-to-End Communications Testing
Integrated test of SLS core and upper stages, and Orion command and telemetry radio frequencies with mission control at NASA’s Johnson Space Center in Houston to demonstrate flight controllers’ ability to communicate with the ground systems and infrastructure. This test uses a radio frequency antenna in the Vehicle Assembly Building (VAB), another near the launch pad that will cover the first few minutes of launch, as well as a radio frequency that use the Tracking Data Relay Satellite and the Deep Space Network. Teams will do two versions of this test – one with the ground equipment communicating with a radio and telemetry station for checkouts, and one with all the hardware and equipment communicating with communications infrastructure like it will on launch day.
Countdown Demonstration Test
Teams will conduct a launch day demonstration with the Artemis II astronauts to test launch countdown procedures and make any final necessary adjustments ahead of launch. This test will be divided into two parts. The first will be conducted while SLS and Orion are in the VAB and include the Artemis II crew departing their crew quarters after suiting up at the Neil A. Armstrong Operations and Checkout Building and driving to the VAB where they will enter Orion like they will on launch day and practice getting strapped in. Part two will be completed once the rocket is at the launch pad and will allow the astronauts and Artemis launch team to practice how to use the emergency egress system, which would be used in the event of an unlikely emergency at the launch pad during launch countdown.
Flight Termination System End-to-End Test
Test to ensure the rocket’s flight termination system can be activated in the event of an emergency. For public safety, all rockets are required to have a flight termination system. This test will be divided into two parts inside the VAB. The first will take place ahead of Orion getting stacked atop SLS and the second will occur before the rocket and spacecraft roll out to the launch pad.
Wet Dress Rehearsal
Teams will practice loading cryogenic liquid propellant inside SLS once it’s at the launch pad and run through the launch countdown sequences just prior to engine ignition. The rehearsal will run the Artemis II launch team through operations to load liquid hydrogen and liquid oxygen into the rocket’s tanks, conduct a full launch countdown, demonstrate the ability to recycle the countdown clock, and also drain the tanks to give them an opportunity to practice the timelines and procedures they will use for launch.
Teams will load more than 700,000 gallons of cryogenic, or super cold, propellants into the rocket at the launch pad on the mobile launcher according to the detailed timeline they will use on the actual launch day. They will practice every phase of the countdown, including weather briefings, pre-planned holds in the countdown, conditioning and replenishing the propellants as needed, and validation checks. The Artemis II crew will not participate in the rehearsal.
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Mapping Sub-cm Orbital Debris in LEO concept.NASA/Christine Hartzell Christine Hartzell
University of Maryland, College Park
The proposed investigation will address key technological challenges associated with a previously funded NIAC Phase I award titled “On-Orbit, Collision-Free Mapping of Small Orbital Debris”. Sub-cm orbital debris in LEO is not detectable or trackable using conventional technologies and poses a major hazard to crewed and un-crewed spacecraft. Orbital debris is a concern to NASA, as well as commercial and DoD satellite providers. In recent years, beginning with our NIAC Phase I award, we have been developing the idea that the sub-cm orbital debris environment may be monitored by detecting the plasma signature of the debris, rather than optical or radar observations of the debris itself. Our prior work has shown that sub-cm orbital debris may produce plasma solitons, which are a type of wave in the ionosphere plasma that do not disperse as readily as traditional waves. Debris may produce solitons that are co-located with the debris (called pinned solitons) or that travel ahead of the debris (called precursor solitons). We have developed computational models to predict the characteristics of the plasma solitons generated by a given piece of debris. These solitons may be detectable by 12U smallsats outfitted with multi-needle Langmuir probes.
In this Phase II NIAC award, we will address two key technical challenges that significantly effect the value of soliton-based debris detection: 1. Develop an algorithm to constrain debris size and speed based on observed soliton characteristics. Our prior investigations have produced predictions of soliton characteristics as a function of debris characteristics. However, the inverse problem is not analytically solvable. We will develop machine learning algorithms to address this challenge. 2. Evaluate the feasibility and value of detecting soliton velocity. Multiple observations of the same soliton may allow us to constrain the distance that the soliton has traveled from the debris. When combined with the other characteristics of the soliton and knowledge of the local plasma environment, back propagation of the soliton in plasma simulations may allow us to extract the position and velocity vectors of the debris. If it is possible to determine debris size, position and velocity from soliton observations, this would provide a breakthrough in space situational awareness for debris that is currently undetectable using conventional technology. However, even if only debris size and speed can be inferred from soliton detections, this technology is still a revolutionary improvement on existing methods of characterizing the debris flux, which provide data only on a multi-year cadence. This proposed investigation will answer key technological questions about how much information can be extracted from observed soliton signals and trade mission architectures for complexity and returned data value. Additionally, we will develop a roadmap to continue to advance this technology.
2025 Selections
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Last Updated May 27, 2025 EditorLoura Hall Related Terms
NIAC Studies NASA Innovative Advanced Concepts (NIAC) Program Keep Exploring Discover More NIAC Topics
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NASA Innovative Advanced Concepts
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies concept.NASA/Benjamin Hockman Benjamin Hockman
NASA Jet Propulsion Laboratory
The goal of this effort is to develop a robust and affordable mission architecture that enables the gravimetric density reconstruction of small body interiors to unprecedented precision. Our architecture relies on the novel concept of “Gravity Poppers,” which are small, minimalistic probes that are deployed to the surface of a small body and periodically “pop” so as to perpetuate a random hopping motion around the body. By tracking a large swarm of poppers from orbit, a mother spacecraft can precisely estimate their trajectories and continuously refine a high-resolution map of the body’s gravity field, and thus, its internal mass distribution. Hopping probes are also equipped with minimalistic in-situ sensors to measure the surface temperature (when landed) and strength (when bouncing) in order to complement the gravity field and build a more accurate picture of the interior. The Phase I study focused on feasibility assessment of three core technologies that enable such a mission: (1) the mechanical design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to iteratively refine a gravity model of the body. The key finding was that the concept is feasible, and demonstrated to have the potential to resolve extremely accurate gravity models, allowing scientists to localize density anomalies such as “weighing” large boulders on the surface. This Phase II Proposal aims to further develop these three core technologies through continued mission trade studies and sensitivity analysis, case studies for simulated missions, and hardware prototypes demonstrating both hopping behavior and tracking performance.
2025 Selections
Facebook logo @NASATechnology @NASA_Technology
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Last Updated May 27, 2025 EditorLoura Hall Related Terms
NIAC Studies NASA Innovative Advanced Concepts (NIAC) Program Keep Exploring Discover More NIAC Topics
Space Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
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By NASA
6 Min Read A Defining Era: NASA Stennis and Space Shuttle Main Engine Testing
The numbers are notable – 34 years of testing space shuttle main engines at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, 3,244 individual tests, more than 820,000 seconds (totaling more than nine days) of cumulative hot fire.
The story behind the numbers is unforgettable.
“It is hard to describe the full impact of the space shuttle main engine test campaign on NASA Stennis,” Center Director John Bailey said. “It is hundreds of stories, affecting all areas of center life, within one great story of team achievement and accomplishment.”
NASA Stennis tested space shuttle main engines from May 19, 1975, to July 29, 2009. The testing made history, enabling 135 shuttle missions and notable space milestones, like deployment of the Hubble Space Telescope and construction of the International Space Station.
The testing also:
Established NASA Stennis as the center of excellence for large propulsion testing. Broadened and deepened the expertise of the NASA Stennis test team. Demonstrated and expanded the propulsion test capabilities of NASA Stennis. Ensured the future of the Mississippi site. The first space shuttle main engine is installed on May 8, 1975, at the Fred Haise Test Stand (formerly A-1). The engine would be used for the first six tests and featured a shortened thrust chamber assembly.NASA Assignment and Beginning
NASA Stennis was not the immediate choice to test space shuttle main engines. Two other sites also sought the assignment – NASA’s Marshall Flight Center in Alabama and Edwards Air Force Base in California. However, following presentations and evaluations, NASA announced March 1, 1971, that the test campaign would take place in south Mississippi.
“(NASA Stennis) was now assured of a future in propulsion testing for decades,” summarized Way Station to Space, a history of the center’s first decades.
Testing did not begin immediately. First, NASA Stennis had to complete an ambitious project to convert stands built the previous decade for rocket stage testing to facilities supporting single-engine hot fire.
Propellant run tanks were installed and calibrated. A system was fashioned to measure and verify engine thrust. A gimbaling capability was developed on the Fred Haise Test Stand to allow operators to move engines as they must pivot in flight to control rocket trajectory. Likewise, engineers designed a diffuser capability for the A-2 Test Stand to allow operators to test at simulated altitudes up to 60,000 feet.
NASA Stennis teams also had to learn how to handle cryogenic propellants in a new way. For Apollo testing, propellants were loaded into stage tanks to support hot fires. For space shuttle, propellants had to be provided by the stand to the engine. New stand run tanks were not large enough to support a full-duration (500 seconds) hot fire, so teams had to provide real-time transfer of propellants from barges, to the run tanks, to the engine.
The process required careful engineering and calibration. “There was a lot to learn to manage real-time operations,” said Maury Vander, chief of NASA Stennis test operations. “Teams had to develop a way to accurately measure propellant levels in the tanks and to control the flow from barges to the tanks and from the tanks to the engine. It is a very precise process.”
NASA Stennis teams conduct a hot fire of the space shuttle Main Propulsion Test Article in 1979 on the B-2 side of the Thad Cochran Test Stand. The testing involved installing a shuttle external fuel tank, a mockup of the shuttle orbiter, and the vehicle’s three-engine configuration on the stand, then firing all three engines simultaneously as during an actual launch.NASA Testing the Way
The biggest challenge was operation of the engine itself. Not only was it the most sophisticated ever developed, but teams would be testing a full engine from the outset. Typically, individual components are developed and tested prior to assembling a full engine. Shuttle testing began on full-scale engines, although several initial tests did feature a trimmed down thrust chamber assembly.
The initial test on May 19, 1975, provided an evaluation of team and engine. The so-called “burp” test did not feature full ignition, but it set the stage for moving forward.
“The first test was a monstrous milestone,” Vander said. “Teams had to overcome all sorts of challenges, and I can only imagine what it must have felt like to go from a mostly theoretical engine to seeing it almost light. It is the kind of moment engineers love – fruits-of-all-your-hard-labor moment.”
NASA Stennis teams conducted another five tests in quick succession. On June 23/24, with a complete engine thrust chamber assembly in place, teams achieved full ignition. By year’s end, teams had conducted 27 tests. In the next five years, they recorded more than 100 annual hot fires, a challenging pace. By the close of 1980, NASA Stennis had accumulated over 28 hours of hot fire.
The learning curve remained steep as teams developed a defined engine start, power up, power down, and shutdown sequences. They also identified anomalies and experienced various engine failures.
“Each test is a semi-controlled explosion,” Vander said. “And every test is like a work of art because of all that goes on behind the scenes to make it happen, and no two tests are exactly the same. There were a lot of knowledge and lessons learned that we continue to build on today.”
NASA Stennis test conductor Brian Childers leads Test Control Center operations during the 1000th test of a space shuttle main engine on the Fred Haise Test Stand (formerly A-1). on Aug. 17, 2006.NASA Powering History
Teams took a giant step forward in 1978 to 1981 with testing of the Main Propulsion Test Article, which involved installing three engines (configured as during an actual launch), with a space shuttle external tank and a mock orbiter, on the B-2 side of the Thad Cochran Test Stand.
Teams conducted 18 tests of the article, proving conclusively that the shuttle configuration would fly as needed. On April 12, 1981, shuttle Columbia launched on the maiden STS-1 mission of the new era. Unlike previous vehicles, this one had no uncrewed test flight. The first launch of shuttle carried astronauts John Young and Bob Crippen.
“The effort that you contributed made it possible for us to sit back and ride,” Crippen told NASA Stennis employees during a post-test visit to the site. “We couldn’t even make it look hard.”
Testing proceeded steadily for the next 28 years. Engine anomalies, upgrades, system changes – all were tested at NASA Stennis. Limits of the engine were tested and proven. Site teams gained tremendous testing experience and expertise. NASA Stennis personnel became experts in handling cryogenics.
Following the loss of shuttles Challenger and Columbia, NASA Stennis teams completed rigorous test campaigns to ensure future mission safety. The space shuttle main engine arguably became the most tested, and best understood, large rocket engine in the world – and NASA Stennis teams were among those at the forefront of knowledge.
NASA conducts the final space shuttle main engine test on July 29, 2009, on the A-2 Test Stand at NASA Stennis. The Space Shuttle Program concluded two years later with the STS-135 shuttle mission in July 2011.NASA A Foundation for the Future
NASA recognized the effort of the NASA Stennis team, establishing the site as the center of excellence for large propulsion test work. In the meanwhile, NASA Stennis moved to solidify its future, growing as a federal city, home to more than 50 resident agencies, organizations, and companies.
Shuttle testing opened the door for the variety of commercial aerospace test projects the site now supports. It also established and solidified the test team’s unique capabilities and gave all of Mississippi a sense of prideful ownership in the Space Shuttle Program – and its defining missions.
No one can say what would have happened to NASA Stennis without the space shuttle main engine test campaign. However, everything NASA Stennis now is rests squarely on the record and work of that history-making campaign.
“Everyone knows NASA Stennis as the site that tested the Apollo rockets that took humans to the Moon – but space shuttle main engine testing really built this site,” said Joe Schuyler, director of NASA Stennis engineering and test operations. “We are what we are because of that test campaign – and all that we become is built on that foundation.”
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Last Updated May 19, 2025 EditorNASA Stennis CommunicationsContactC. Lacy Thompsoncalvin.l.thompson@nasa.gov / (228) 688-3333LocationStennis Space Center Related Terms
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s X-59 quiet supersonic research aircraft is seen during its “aluminum bird” systems testing at Lockheed Martin’s Skunk Works facility in Palmdale, California. The test verified how the aircraft’s hardware and software work together, responding to pilot inputs and handling injected system failures. Lockheed Martin / Garry Tice NASA’s X-59 quiet supersonic research aircraft successfully completed a critical series of tests in which the airplane was put through its paces for cruising high above the California desert – all without ever leaving the ground.
“The idea behind these tests is to command the airplane’s subsystems and flight computer to function as if it is flying,” said Yohan Lin, the X-59’s lead avionics engineer at NASA’s Armstrong Flight Research Center in Edwards, California.
The goal of ground-based simulation testing was to make sure the hardware and software that will allow the X-59 to fly safely are properly working together and able to handle any unexpected problems.
Any new aircraft is a combination of systems, and identifying the little adjustments required to optimize performance is an important step in a disciplined approach toward flight.
“We thought we might find a few things during the tests that would prompt us to go back and tweak them to work better, especially with some of the software, and that’s what we wound up experiencing. So, these tests were very helpful,” Lin said.
Completing the tests marks another milestone off the checklist of things to do before the X-59 makes its first flight this year, continuing NASA’s Quesst mission to help enable commercial supersonic air travel over land.
Simulating the Sky
During the testing, engineers from NASA and contractor Lockheed Martin turned on most of the X-59’s systems, leaving the engine off. For example, if the pilot moved the control stick a certain way, the flight computer moved the aircraft’s rudder or other control surfaces, just as it would in flight.
At the same time, the airplane was electronically connected to a ground computer that sends simulated signals – which the X-59 interpreted as real – such as changes in altitude, speed, temperature, or the health of various systems.
Sitting in the cockpit, the pilot “flew” the aircraft to see how the airplane would respond.
“These were simple maneuvers, nothing too crazy,” Lin said. “We would then inject failures into the airplane to see how it would respond. Would the system compensate for the failure? Was the pilot able to recover?”
Unlike in typical astronaut training simulations, where flight crews do not know what scenarios they might encounter, the X-59 pilots mostly knew what the aircraft would experience during every test and even helped plan them to better focus on the aircraft systems’ response.
NASA test pilot James Less sits in the cockpit of the X-59 quiet supersonic research aircraft as he participates in a series of “aluminum bird” systems tests at Lockheed Martin’s Skunk Works facility in Palmdale, California.Lockheed Martin / Garry Tice Aluminum vs. Iron
In aircraft development, this work is known as “iron bird” testing, named for a simple metal frame on which representations of the aircraft’s subsystems are installed, connected, and checked out.
Building such a testbed is a common practice for development programs in which many aircraft will be manufactured. But since the X-59 is a one-of-a-kind airplane, officials decided it was better and less expensive to use the aircraft itself.
As a result, engineers dubbed this series of exercises “aluminum bird” testing, since that’s the metal the X-59 is mostly made of.
So, instead of testing an “iron bird” with copies of an aircraft’s systems on a non-descript frame, the “aluminum bird” used the actual aircraft and its systems, which in turn meant the test results gave everyone higher confidence in the design,
“It’s a perfect example of the old tried and true adage in aviation that says ‘Test what you fly. Fly what you test,’” Lin said.
Still Ahead for the X-59
With aluminum bird testing in the rearview mirror, the next milestone on the X-59’s path to first flight is take the airplane out on the taxiways at the airport adjacent to Lockheed Martin’s Skunk Works facility in Palmdale, California, where the X-59 was built. First flight would follow those taxi tests.
Already in the X-59’s logbook since the fully assembled and painted airplane made its public debut in January 2024:
A Flight Readiness Review in which a board of independent experts from across NASA completed a study of the X-59 project team’s approach to safety for the public and staff during ground and flight testing. A trio of important structural tests and critical inspections that included “shaking” the airplane to make sure there were no unexpected problems from the vibrations. Firing up the GE Aerospace jet engine for the first time after installation into the X-59, including a series of tests of the engine running with full afterburner. Checking the wiring that ties together the X-59’s flight computer, electronic systems, and other hardware to be sure there were no concerns about electromagnetic interference. Testing the aircraft’s ability to maintain a certain speed while flying, essentially a check of the X-59’s version of cruise control. The X-59 Tests in 59
Watch this video about the X-59 aluminum bird testing. It only takes a minute. Well, 59 seconds to be precise. About the Author
Jim Banke
Managing Editor/Senior WriterJim Banke is a veteran aviation and aerospace communicator with more than 40 years of experience as a writer, producer, consultant, and project manager based at Cape Canaveral, Florida. He is part of NASA Aeronautics' Strategic Communications Team and is Managing Editor for the Aeronautics topic on the NASA website.
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Last Updated May 15, 2025 EditorJim BankeContactMatt Kamletmatthew.r.kamlet@nasa.gov Related Terms
Aeronautics Advanced Air Vehicles Program Aeronautics Research Mission Directorate Ames Research Center Armstrong Flight Research Center Commercial Supersonic Technology Glenn Research Center Integrated Aviation Systems Program Langley Research Center Low Boom Flight Demonstrator Quesst (X-59) Quesst: The Vehicle Supersonic Flight View the full article
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