Knowledge Guide

Advanced air mobility

NASA coined this term in early 2020 to encompass the automated (or optionally piloted) electric aircraft that would move “people and cargo between places previously not served or underserved by aviation — local, regional, intraregional, urban,” as NASA’s AAM website puts it. AAM includes urban and regional air mobility designs, and often refers to electric vertical takeoff and landing concepts.

Source: NASA Aeronautics Research Mission Directorate

Updated: June 3, 2021

Author: Cat Hofacker

Ariane 5

This latest iteration of the expendable Ariane rocket design was first launched in 1996 by Arianespace, the France-based company established in 1980 to launch and market rockets developed with European Space Agency funding. Ariane 5s have sent 261 spacecraft to orbit, but during that inaugural flight from Kourou, French Guiana, the onboard autonomous navigation software failed, and the rocket veered off course and exploded. One of the final Ariane 5 flights will be the launch of NASA’s James Webb Space Telescope, currently scheduled for December 2021, after which ESA plans to phase out the Ariane 5 and shift to the in-development Ariane 6. That design’s inaugural flight is scheduled for mid-2022.

Source: Arianespace and ESA websites; 1996 accident report; Aerospace America reporting

Updated: Oct. 21, 2021

Author: Cat Hofacker


In March 2019, Vice President Mike Pence announced during a National Space Council meeting that NASA would land “the first woman and the next man on the moon” by 2024. Then, in May, NASA announced the program’s name as Artemis, after Apollo’s twin sister in Greek mythology. NASA plans to send astronauts about once per year to construct an Artemis Base Camp. The NASA Office of Inspector General in February 2021 placed the Artemis cost at $86 billion through fiscal 2025. The Biden administration in February voiced support for Artemis, and during his April confirmation hearing Administrator Bill Nelson said the agency would stick to the 2024 goal.

Source: NASA Headquarters; NASA Office of Inspector General; Trump White House archives; Aerospace America reporting

Updated: June 6, 2021

Author: Cat Hofacker

Artemis Accords

NASA, in May 2020, published a set of principles on its website challenging the nations of the world to maintain peace “on and around the moon” by abiding by the1967 Outer Space Treaty and committing to explore for “peaceful purposes” only. Signatories to the Artemis Accords, named for NASA’s Artemis lunar program, pledge to register all “space objects,” extract resources only in compliance with the 1967 treaty, avoid “harmful interference” with each other, and meet a host of other principles. Twelve countries have signed onto the Artemis Accords.

Source: NASA Headquarters

Updated: June 18, 2021

Author: Cat Hofacker

ASTM International

This standards body headquartered in Pennsylvania crafts the technical standards for wide-ranging applications, including aircraft components and synthetic jet fuels. Established by a group of Pennsylvania Railroad engineers and scientists in 1898 as the American Society for Testing and Materials, ASTM originally focused on analyzing and issuing specifications for railroad materials but has gradually grown to include industries including aerospace. In the ensuing decades, the organization expanded its membership beyond the United States prompting the 2001 name change to ASTM International.

Source: ASTM website; AeroAm reporting

Updated: May 4, 2021

Author: Cat Hofacker

Atlas V

The latest variant of the expendable Atlas rockets, originally designed as Intercontinental Ballistic Missiles that would launch U.S. warheads. Lockheed Martin developed the Atlas V design, the first vehicle of which flew in 2002, with funds from the U.S. Air Force under its Evolved Expendable Launch Vehicle program of the 1990s and early 2000s. United Launch Alliance, a joint venture of Boeing and Lockheed Martin, is developing a replacement launch vehicle, the Vulcan Centaur, partly because a 2014 U.S. law prohibits launching defense and intelligence satellites after Dec. 31, 2022, via the Russian-made RD-180 engines, meaning those that power each Atlas first stage.

Source: Lockheed Martin and United Launch Alliance websites

Updated: March 3, 2021

Author: Cat Hofacker

Boeing 737 MAX

Airlines resumed flying these single-aisle jets in November 2020 after two crashes prompted aviation authorities around the world to ground the planes in March 2019. In the 2018 Lion Air and 2019 Ethiopian Airlines crashes, the anti-stall software unique to the MAX, called MCAS, short for Maneuvering Characteristics Augmentation System, forced the noses of the planes down repeatedly in response to readings from faulty sensors that indicated the planes were approaching a stall. FAA conducted a 20-month safety review that concluded in November 2020, at which time Boeing and airlines around the world were cleared to update the planes’ flight software and ready them for flight. In the U.S., American Airlines was the first to resume MAX flights in December.

Source: FAA; U.S. House transportation committee; Aerospace America reporting

Updated: May 4, 2021

Author: Cat Hofacker

Commercial Lunar Payload Services (CLPS)

The first two NASA-contracted CLPS launches to the moon are scheduled for 2022, when Astrobotic’s Peregrine robotic lander rides atop a United Launch Alliance Vulcan Centaur rocket, and early 2022, when the Nova-C robotic lander from Intuitive Machines goes up on a SpaceX Falcon 9. This year-long delay of the original 2021 launch dates was prompted in part by the covid-19 pandemic, both companies said. NASA established the CLPS program in 2018 to pay private companies to send equipment and rovers to the lunar surface ahead of the first Artemis astronaut landing. NASA has so far approved 14 vendors, meaning companies who are eligible for CLPS awards and has awarded six contracts. These leave it up to the awardee to choose the launch provider.

Source: NASA Headquarters; Aerospace America reporting

Updated: June 23, 2021

Author: Cat Hofacker

Curiosity rover

NASA launched this 6-wheeled rover in 2011 for the Mars Science Laboratory mission, which aims to determine whether Mars was once capable of supporting microbial life. Curiosity’s August 2012 landing on Mars was the first to utilize the sky crane maneuver, in which the 899-kilogram rover was lowered on a tether to the surface. The rover is currently exploring Mount Sharp, a 5-kilometer-tall mountain in the Gale Crater. Curiosity travels an average of 30 meters per day, scooping up and drilling into rocks for its onboard instruments to analyze. The instruments have detected traces of sulfur, carbon and other organic compounds.

Source: NASA's Jet Propulsion Lab; Aerospace America reporting

Updated: April 7, 2021

Author: Cat Hofacker

Dragon 2

SpaceX’s fleet of reusable spacecraft, consisting of cargo and crew variants that ferry astronauts and supplies to International Space Station and back for NASA. An earlier version of the Cargo Dragon design was grappled by the ISS robotic arm, but both Dragon 2 variants dock directly to the station. In late 2020, NASA certified the Dragon design for contracted crewed flights, following the two-person test flight dubbed Demo-2 earlier that year. The first of those contracted flights occurred in November 2020 when a Dragon 2 carried four astronauts to ISS as the first of six crewed flights under a 2014 contract. SpaceX also plans to book customers outside NASA, and has two private flights scheduled through 2022: the Inspiration 4 launch four tourists in September 2021 for a five-day orbital trip through Space Adventures, and an eight-day stay at ISS for one Axiom astronaut and three private citizens in 2022 dubbed Ax-1.

Source: SpaceX announcements; Aerospace America reporting

Updated: June 9, 2021

Author: Cat Hofacker

Dream Chaser

A cargo version of this lifting-body spaceplane design from Sierra Nevada Corp. is under construction and scheduled for a first flight in 2022 atop a ULA Vulcan Centaur rocket with supplies for the International Space Station. This particular spaceplane, dubbed Tenacity, and all future Dream Chasers, will glide back and land on a runway like the space shuttle. Between 2013 and 2017, SNC completed a series of drop tests to demonstrate this landing technique, dropping the Dream Chaser Engineering Test Article from an altitude of 12,000 feet multiple times. Long term, SNC plans to build a crew version of Dream Chaser that would hold 7 passengers once the cargo variant begins operations.

Source: SNC fact sheet; NASA Headquarters

Updated: March 23, 2021

Author: Cat Hofacker


The first spacecraft of this joint European-Russian ExoMars mission, the Trace Gas Orbiter, has been circling Mars since 2017 to act as a communications relay for the mission’s other spacecraft: 1. the Airbus-built Rosalind Franklin rover, funded by the European Space Agency and named after the English chemist of DNA fame, and 2. The Russian-built Kazachok or “little Cossack” platform from which the rover will roll. Both are scheduled for launch aboard a Proton in 2022, four years late. The two supersonic parachutes that must slow the assembly during descent ripped during 2019 tests in Sweden.

Source: ESA press releases; Aerospace America reporting

Updated: April 8, 2021

Author: Cat Hofacker

Falcon 9

As of early June, SpaceX has flown a variant of the Falcon 9 rocket design 120 times including the inaugural flight carrying a test version of the company’s Dragon capsule in 2010. As of May, SpaceX had reflown an individual Falcon 9 booster 10 times, previously thought to be the limit of the Falcon 9 design. SpaceX now plans to push the limits of the booster design, recovering first stages via vertical touchdowns aboard drone ships, and less frequently at its Cape Canaveral launch pad, facilitated by retrorockets and retractable landing legs. SpaceX first reflew a Falcon 9 booster in 2017. In April 2021 NASA cleared a previously flown booster for the launch of four astronauts to the International Space Station for the Crew-2 mission.

Source: SpaceX press releases and social media; AeroAm reporting

Updated: June 3, 2021

Author: Cat Hofacker

Human Landing System (HLS)

In a departure from the NASA-owned lunar landers of the Apollo era, NASA’s Artemis program plans to pay for astronauts to ride in corporate-owned landers from lunar orbit to the moon’s surface. NASA in April awarded a single $2.89 billion contract to SpaceX to conduct an uncrewed and crewed mission by 2024, prompting the other competitors Blue Origin and Dynetics to file protests with the U.S. Government Accountability Office. The agency had awarded a combined $967 million to Blue Origin, Dynetics and SpaceX in 2020 to refine their lander concepts, the plan being to select at least two lander designs for additional funding in a model similar to the Commercial Crew program. But NASA said Congress did not appropriate enough funds in fiscal 2021 for the agency to award two contracts for the 2024 mission, so the agency plans to solicit additional lander designs in future competitions. NASA has estimated that the HLS program will cost $16 billion between fiscal 2021 and fiscal 2025.

Source: NASA press releases and budget documents; Aerospace America reporting

Updated: June 3, 2021

Author: Cat Hofacker

James Webb Space Telescope (JWST)

NASA’s $9.7 billion mission to peer back in time to the era 150 million to 200 million years after the Big Bang. Scientists expect to see the formation of hot gases into stars, planets and galaxies. Conceived in 1996, Webb was originally scheduled to be launched between 2007 and 2011, but NASA and prime contractor Northrop Grumman experienced a series of delays and cost overruns mainly related to the sunshield and valves that would pump propellant to the spacecraft’s thrusters. Webb is scheduled to be launched on an Ariane 5 rocket on Dec. 18, 2021, into an orbit around the second Lagrange point, a location beyond Earth relative to the sun. Once unfolded, its 6.5-meter primary mirror will collect infrared light from these early features. Plans call for a five-year mission, but NASA says there’s enough fuel to point the spacecraft and maintain its orbit for at least 10 years.

Source: 1996 report “HST and Beyond”; NASA 2010 independent review; Aerospace America reporting

Updated: Sept. 8, 2021

Author: Cat Hofacker

Low-Boom Flight Demonstration program

NASA’s program to gather acoustic and community response data that could help the United Nations’ International Civil Aviation Organization craft a global noise standard for aircraft flying faster than Mach 1. In the United States, overland supersonic flights have been banned since 1973 for fear that sonic booms would be a nuisance to residents. NASA plans to fly the X-59 demonstrator, now under construction, over populated areas starting in 2024 and survey residents to gather their reactions. NASA and Lockheed Martin designed the X-59 to reduce the sonic boom to a “thump” about as loud as closing a car door.

Source: NASA Aeronautics fact sheets and news releases; Aerospace America reporting

Updated: April 1, 2021

Author: Cat Hofacker

Maneuvering Characteristics Augmentation System (MCAS)

This software on Boeing 737 MAX jets, in its original form, forced the nose down if readings from one angle-of-attack sensor indicated danger of aerodynamic stall. During the MAX crashes, MCAS pushed the nose of the planes down repeatedly as the crews struggled. After the first crash, FAA ordered Boeing to modify MCAS to only activate when it receives matching readings from both AoA sensors, and to only activate once. After the second crash, additional steps included more pilot training and new checklists pertaining to MCAS, which wasn’t referenced in pilot manuals prior to the 2018 and 2019 MAX crashes.

Source: FAA; U.S. House transportation committee and Senate Commerce Committee; Aerospace America reporting

Updated: June 10, 2020

Author: Cat Hofacker


The illusion of complete or partial weightlessness during free fall toward Earth. The term can be misleading. Consider the International Space Station. While gravity’s strength decreases with distance, at the altitude of ISS gravity aboard is still 90% as strong as at Earth’s surface. Because the station and everything inside it are in free fall, objects float and feel weightless, but they stay aloft by circling Earth fast enough that they continually fall beyond Earth’s curve. The sensation of reduced or zero gravity can also be created by flying an aircraft in a parabola pattern, with the maneuvers tailored to achieve specific G forces.

Source: NASA; Zero Gravity Corp

Updated: March 3, 2021

Author: Ben Iannotta

New Shepard

Blue Origin’s reusable booster-and-capsule design sent its first passengers, which included founder Jeff Bezos, to the fringes of space and back on July 20, 2021, in a flight from West Texas. Blue has so far launched four New Shepard boosters on a total of 17 flights with unoccupied capsules since 2015, and a total of two passenger flights in 2021. During each flight, the capsule separates from the booster, which then heads back and lands vertically via retrorockets, while the capsule proceeds to space and returns for a landing under parachutes. Two New Shepard rockets currently fly — New Shepard 3 for cargo flights and New Shepard 4 exclusively for passenger flights. The 11-minute autonomous rides can send up to six passengers to a maximum altitude of about 100 kilometers for three minutes of weightlessness and panoramic views of Earth through six rounded rectangular windows. With a combined surface area of 4.2 square meters, the windows comprise one-third of the capsule’s surface area.

Source: Blue Origin executives and website; Aerospace America reporting

Updated: Oct. 13, 2021

Author: Cat Hofacker


Short for Next Generation Air Transportation System, this upgrade of aircraft surveillance equipment and air traffic control facilities is a multi-year modernization initiative the FAA will be working on through at least 2025. Most recently, all general aviation aircraft in the U.S. were required to be equipped with ADS-B Out transponders that broadcast their identity and location to Iridium satellites, other aircraft and air traffic control stations.

Source: FAA

Updated: Jan. 6, 2020

Author: Cat Hofacker

Organization Designation Authorization (ODA)

The FAA’s program created in 2005 to streamline certification by delegating authority to employees at companies to sign off on certain aspects of an aircraft’s design. In the wake of the Boeing 737 MAX crashes, FAA has been criticized for using ODA to “self-certify,” a term the agency says mischaracterizes the ODA program. In September 2020, the U.S. House of representatives introduced legislation requiring FAA to have more direct oversight over companies completing work under ODAs. In December 2020, then-President Donald Trump signed the “Aircraft Certification, Safety and Accountability Act” into law.

Source: FAA; House Transportation and Senate Commerce committees

Updated: April 8, 2021

Author: Cat Hofacker

Space Launch System (SLS)

For this line of next-generation expendable rockets, NASA originally estimated it would need $10 billion to cover the design and construction leading to an unoccupied test flight in 2017. As of September, the agency has spent $19.6 billion on the SLS program and has not released a more specific date for the inaugural flight with an unoccupied Orion crew capsule beyond late 2021 or early 2022. Born out of a congressional mandate in the 2010 NASA authorization, the initial SLS design, called Block 1, would loft between 70 and 100 metric tons to low-Earth orbit. The Boeing-built SLS core stage carries a liquid hydrogen tank and a liquid oxygen tank to deliver propellant to four Aerojet Rocketdyne RS-25 engines that previously flew on multiple space shuttle missions. NASA plans to conduct the first three missions of the Artemis moon program aboard SLS Block 1s, then switch to an in-development SLS variant, Block 1B, which could loft 105 metric tons with its more powerful upper stage.

Source: NASA Authorization Act of 2010; NASA Office of Inspector General; NASA releases; Aerospace America reporting

Updated: Sept. 24, 2021

Author: Cat Hofacker

Space situational awareness

Refers to the knowledge such as the identities and orbits of satellites that companies and authorities must have in order to avert collisions between satellites or with debris. The U.S. maintains its SSA at the interagency National Space Defense Center at Schriever Air Force Base in Colorado, based in part on tracking and identification information from the U.S. Space Force 18th Space Control Squadron at Vandenberg Air Force Base. The Trump administration in 2018 directed the Department of Commerce to assume SSA monitoring and collision warnings for nonmilitary spacecraft, but Congress has yet to approve the necessary funding.

Source: Aerospace America reporting, Space Foundation

Updated: Feb. 26, 2020

Author: Cat Hofacker


SpaceX’s $10 billion venture to build a 4,400-satellite constellation that will provide broadband internet to consumers from altitudes between 540 kilometers and 570 kilometers, thus avoiding the signal latency of today’s satellite internet providers in geosynchronous orbits 35,000 km over the equator. SpaceX has been cleared by the U.S. Federal Communications Commission to launch the first 12,000 satellites, and is awaiting approval for the additional 30,000 spacecraft. Twice monthly launches of 60 satellites began in 2019 on Falcon 9 rockets. During launch, the flat, rectangular spacecraft built by SpaceX in Redmond, Washington, are stacked like tabletops inside the rocket’s nosecone. Each satellite has a single solar panel that must unfurl like a paper map after deployment. SpaceX has about 1,800 satellites on orbit and in October 2020 began beta tests with Starlink.


Source: Gwynne Shotwell TedTalk; FCC application; Aerospace America

Updated: Oct. 15, 2021

Author: Cat Hofacker

Sustainable aviation fuel (SAF)

The ASTM International standards body has certified five conversion processes for these jet fuels — also called alternative fuels, synthetic fuels and synthetic kerosene — derived from feedstocks ranging from used cooking oil to agricultural residue to be blended in a 50/50 ratio with conventional kerosene jet fuel, another two to be blended in 10/90 ratios and one in a 5/95 ratio. Jet engines burning SAFs emit about the same amount of carbon dioxide as when they burn conventional fossil fuels, but the net increase in atmospheric carbon is minimal: In the case of crop residue, those plants absorb CO2 as they grow, which offsets the amount of CO2 expelled when that plant is converted into SAF and burned for combustion by a jet engine. This is referred to as the lifecycle emissions.


Source: IATA, ASTM International, CAAFI, Aerospace America reporting

Updated: Aug 3, 2021

Author: Cat Hofacker

VSS Unity (Virgin Space Ship)

This is the second SpaceShipTwo piloted spaceplane built for Virgin Galactic by Scaled Composites. It has been to the fringes of space and back four times, surpassing the 80-kilometer boundary the U.S. Air Force considers the edge of space in 2018, 2019 and twice in 2021. That includes the July 11 flight by Richard Branson, three passengers and two pilots. Each flight begins with the piloted WhiteKnightTwo carrier aircraft, VMS Eve, climbing to about 50,000 feet and releasing Unity. After a few moments, Unity’s rocket motor fires to boost it to altitudes of about 80 kilometers (50 miles), providing passengers with several minutes of weightlessness and views of Earth through 12 circular windows before pilots begin a descent and landing back at Virgin’s hub at the state of New Mexico’s Spaceport America.

Source: Virgin Galactic website; investor presentations; Aerospace America reporting

Updated: July 16, 2021

Author: Cat Hofacker

Vulcan Centaur

United Launch Alliance’s eventual replacement for its Atlas V and Delta IV Heavy rockets is now scheduled to make its debut launch in 2022, due to delays with the Peregrine moon lander in development by Astrobotic, a lunar logistics company in Pittsburgh. ULA must complete that flight and a launch of Sierra Nevada Corp.’s Dream Chaser spaceplane, also scheduled for 2022, before the United States will consider launching billion-dollar spy and military satellites under Phase 2 of the National Security Space Launch program. The deadline is tightening for ULA, because a 2014 law prohibits government launches after 2022 with the Russian-made RD-180 engine that powers the Atlas V upper stage. The Vulcan Centaur first stage will be powered by two BE-4 engines from Blue Origin of Washington state. Up to six solid rocket boosters can be attached to a Vulcan Centaur single-core booster for additional thrust.

Source: U.S. Space Force releases; ULA website; Aerospace America reporting

Updated: June 24, 2021

Author: Cat Hofacker

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