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Galileo satellites’ last step before launch
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By Space Force
The mission successfully achieved a complex effort across multiple Space Force organizations to pull an existing GPS III satellite from storage, accelerate integration and launch vehicle readiness, and rapidly process for launch.
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By European Space Agency
A multi-orbit constellation of about 300 satellites that will deliver resilient, secure and fast communications for EU governments, European companies and citizens will be put in orbit after two contracts were confirmed today in Brussels.
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By NASA
This article is from the 2024 Technical Update
Autonomous flight termination systems (AFTS) are being progressively employed onboard launch vehicles to replace ground personnel and infrastructure needed to terminate flight or destruct the vehicle should an anomaly occur. This automation uses on-board real-time data and encoded logic to determine if the flight should be self-terminated. For uncrewed launch vehicles, FTS systems are required to protect the public and governed by the United States Space Force (USSF). For crewed missions, NASA must augment range AFTS requirements for crew safety and certify each flight according to human rating standards, thus adding unique requirements for reuse of software originally intended for uncrewed missions. This bulletin summarizes new information relating to AFTS to raise awareness of key distinctions, summarize considerations and outline best practices for incorporating AFTS into human-rated systems.
Key Distinctions – Crewed v. Uncrewed
There are inherent behavioral differences between uncrewed and crewed AFTS related to design philosophy and fault tolerance. Uncrewed AFTS generally favor fault tolerance against failure-to-destruct over failing silent
in the presence of faults. This tenet permeates the design, even downto the software unit level. Uncrewed AFTS become zero-fault-to-destruct tolerant to many unrecoverable AFTS errors, whereas general single fault
tolerance against vehicle destruct is required for crewed missions. Additionally, unique needs to delay destruction for crew escape, provide abort options and special rules, and assess human-in-the-loop insight, command, and/or override throughout a launch sequence must be considered and introduces additional requirements and integration complexities.
AFTS Software Architecture Components and Best-Practice Use Guidelines
A detailed study of the sole AFTS currently approved by USSF and utilized/planned for several launch vehicles was conducted to understand its characteristics, and any unique risk and mitigation techniques for effective human-rating reuse. While alternate software systems may be designed in the future, this summary focuses on an architecture employing the Core Autonomous Safety Software (CASS). Considerations herein are intended for extrapolation to future systems. Components of the AFTS software architecture are shown, consisting of the CASS, “Wrapper”, and Mission Data Load (MDL) along with key characteristics and use guidelines. A more comprehensive description of each and recommendations for developmental use is found in Ref. 1.
Best Practices Certifying AFTS Software
Below are non-exhaustive guidelines to help achieve a human-rating
certification for an AFTS.
References
NASA/TP-20240009981: Best Practices and Considerations for Using
Autonomous Flight Termination Software In Crewed Launch Vehicles
https://ntrs.nasa.gov/citations/20240009981 “Launch Safety,” 14 C.F.R., § 417 (2024). NPR 8705.2C, Human-Rating Requirements for Space Systems, Jul 2017,
nodis3.gsfc.nasa.gov/ NASA Software Engineering Requirements, NPR 7150.2D, Mar 2022,
nodis3.gsfc.nasa.gov/ RCC 319-19 Flight Termination Systems Commonality Standard, White
Sands, NM, June 2019. “Considerations for Software Fault Prevention and Tolerance”, NESC
Technical Bulletin No. 23-06 https://ntrs.nasa.gov/citations/20230013383 “Safety Considerations when Repurposing Commercially Available Flight
Termination Systems from Uncrewed to Crewed Launch Vehicles”, NESC
Technical Bulletin No. 23-02 https://ntrs.nasa.gov/citations/20230001890 View the full article
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
On Dec. 10, 1974, NASA launched Helios 1, the first of two spacecraft to make close observations of the Sun. In one of the largest international efforts at the time, the Federal Republic of Germany, also known as West Germany, provided the spacecraft, NASA’s Goddard Space Flight Center in Greenbelt, Maryland, had overall responsibility for U.S. participation, and NASA’s Lewis, now Glenn, Research Center in Cleveland provided the launch vehicle. Equipped with 10 instruments, Helios 1 made its first close approach to the Sun on March 15, 1975, passing closer and traveling faster than any previous spacecraft. Helios 2, launched in 1976, passed even closer. Both spacecraft far exceeded their 18-month expected lifetime, returning unprecedented data from their unique vantage points.
The fully assembled Helios 1 spacecraft prepared for launch.Credit: NASA The West German company Messerchmitt-Bölkow-Blohm built the two Helios probes, the first non-Soviet and non-American spacecraft placed in heliocentric orbit, for the West German space agency DFVLR, today’s DLR. Each 815-pound Helios probe carried 10 U.S. and West German instruments, weighing a total of 158 pounds, to study the Sun and its environment. The instruments included high-energy particle detectors to measure the solar wind, magnetometers to study the Sun’s magnetic field and variations in electric and magnetic waves, and micrometeoroid detectors. Once activated and checked out, operators in the German control center near Munich controlled the spacecraft and collected the raw data. To evenly distribute the solar radiation the spacecraft spun on its axis once every second, and optical mirrors on its surface reflected the majority of the heat.
Workers encapsulate a Helios solar probe into its payload fairing. Credit: NASA
Launch of Helios 1 took place at 2:11 a.m. EST Dec. 10, 1974, from Launch Complex 41 at Cape Canaveral Air Force, now Space Force, Station, on a Titan IIIE-Centaur rocket. This marked the first successful flight of this rocket, at the time the most powerful in the world, following the failure of the Centaur upper stage during the rocket’s inaugural launch on Feb. 11, 1974. The successful launch of Helios 1 provided confidence in the Titan IIIE-Centaur, needed to launch the Viking orbiters and landers to Mars in 1976 and the Mariner Jupiter-Saturn, later renamed Voyager, spacecraft in 1977 to begin their journeys through the outer solar system. The Centaur upper stage placed Helios 1 into a solar orbit with a period of 190 days, with its perihelion, or closest point to the Sun, well inside the orbit of Mercury. Engineers activated the spacecraft’s 10 instruments within a few days of launch, with the vehicle declared fully operational on Jan. 16, 1975. On March 15, Helios 1 reached its closest distance to the Sun of 28.9 million miles, closer than any other previous spacecraft – Mariner 10 held the previous record during its three Mercury encounters. Helios 1 also set a spacecraft speed record, traveling at 148,000 miles per hour at perihelion. Parts of the spacecraft reached a temperature of 261 degrees Fahrenheit, but the instruments continued to operate without problems. During its second perihelion on Sept. 21, temperatures reached 270 degrees, affecting the operation of some instruments. Helios 1 continued to operate and return useful data until both its primary and backup receivers failed and its high-gain antenna no longer pointed at Earth. Ground controllers deactivated the spacecraft on Feb. 18, 1985, with the last contact made on Feb. 10, 1986.
Helios 1 sits atop its Titan IIIE-Centaur rocket at Launch Complex 41 at Cape Canaveral Air Force, now Space Force, Station in Florida.Credit: NASA
Helios 2 launched on Jan. 15, 1976, and followed a path similar to its predecessor’s but one that took it even closer to the Sun. On April 17, it approached to within 27 million miles of Sun, traveling at a new record of 150,000 miles per hour. At that distance, the spacecraft experienced 10% more solar heat than its predecessor. Helios 2’s downlink transmitter failed on March 3, 1980, resulting in no further useable data from the spacecraft. Controllers shut it down on Jan. 7, 1981. Scientists correlated data from the Helios instruments with similar data gathered by other spacecraft, such as the Interplanetary Monitoring Platform Explorers 47 and 50 in Earth orbit, the Pioneer solar orbiters, and Pioneer 10 and 11 in the outer solar system. In addition to their solar observations, Helios 1 and 2 studied the dust and ion tails of the comets C/1975V1 West, C/1978H1 Meier, and C/1979Y1 Bradfield. The information from the Helios probes greatly increased our knowledge of the Sun and its environment, and also raised more questions left for later spacecraft from unique vantage points to try to answer.
llustration of a Helios probe in flight, with all its booms deployed. Credit: NASA The joint ESA/NASA Ulysses mission studied the Sun from vantage points above its poles. After launch from space shuttle Discovery during STS-41 on Oct. 6, 1990, Ulysses used Jupiter’s gravity to swing it out of the ecliptic plane and fly first over the Sun’s south polar region from June to November 1994, then over the north polar region from June and September 1995. Ulysses continued its unique studies during several more polar passes until June 30, 2009, nearly 19 years after launch and more than four times its expected lifetime. NASA’s Parker Solar Probe, launched on Aug. 12, 2018, has made ever increasingly close passes to the Sun, including flying through its corona, breaking the distance record set by Helios 2. The Parker Solar Probe reached its first perihelion of 15 million miles on Nov. 5, 2018, with its closest approach of just 3.86 million miles of the Sun’s surface, just 4.5 percent of the Sun-Earth distance, planned for Dec. 24, 2024. The ESA Solar Orbiter launched on Feb. 10, 2020, and began science operations in November 2021. Its 10 instruments include cameras that have returned the highest resolution images of the Sun including its polar regions from as close as 26 million miles away.
Illustration of the Ulysses spacecraft over the Sun’s pole.Credit: NASA Illustration of the Parker Solar Probe during a close approach to the Sun.Credit: NASA The ESA Solar Orbiter observing the Sun.Credit: NASA About the Author
John J. Uri
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