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Topic Review
Europa Lander (NASA)
The Europa Lander is a proposed astrobiology mission concept by NASA to Europa, an icy moon of Jupiter. If funded and developed as a Flagship mission, it would be launched in 2025 to complement the studies by the Europa Clipper orbiter mission and perform analyses on site. The objectives of the mission are to search for biosignatures at the subsurface ≈10 cm, to characterize the composition of non-ice near-subsurface material, and determine the proximity of liquid water and recently erupted material near the lander's location.
  • 1.8K
  • 28 Oct 2022
Topic Review
Gravity Recovery and Climate Experiment
File:15 Years of Freshwater Trends Seen by GRACE.webm The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center. Twin satellites took detailed measurements of Earth's gravity field anomalies from its launch in March 2002 to the end of its science mission in October 2017. By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth's ocean, geology, and climate. GRACE was a collaborative endeavor involving the Center for Space Research at the University of Texas at Austin, NASA's Jet Propulsion Laboratory, the German Aerospace Center and Germany's National Research Center for Geosciences, Potsdam. The Jet Propulsion Laboratory was responsible for the overall mission management under the NASA ESSP (Earth System Science Pathfinder) program. The principal investigator is Byron Tapley of the University of Texas Center for Space Research, and the co-principal investigator is Christoph Reigber of the GeoForschungsZentrum (GFZ) Potsdam. The two GRACE satellites (GRACE-1 and GRACE-2) were launched from Plesetsk Cosmodrome, Russia, on a Rockot (SS-19 + Breeze upper stage) launch vehicle on 17 March 2002. The spacecraft were launched to an initial altitude of approximately 500 km at a near-polar inclination of 89°. During normal operations, the satellites were separated by 220 km along their orbit track. This system was able to gather global coverage every 30 days. GRACE far exceeded its 5-year design lifespan, operating for 15 years until the decommissioning of GRACE-2 on 27 October 2017. Its successor, GRACE-FO, was successfully launched on 22 May 2018.
  • 1.7K
  • 06 Oct 2022
Topic Review
Space Shuttle Launch Countdown
The launch of Space Shuttle missions was governed by a countdown. Two clocks were maintained, the unofficial, but sometimes mentioned, L (launch) clock represented the time remaining before the scheduled launch in real time, and the more often referred to T (test) clock included several built-in holds where additional verifications were made. Built-in holds were extended if mission parameters allowed for additional checks or to correct issues. Launches of the Space Shuttle to the International Space Station did not allow for holds to be extended due to the launch window which was limited to no more than 10 minutes due to the 90 minute orbit period of the station and speed of Earth's rotation (913.6 miles per hour (1,470.3 km/h) at the Kennedy Space Center), which puts the launch pads 1,000 miles (1,600 km) east of the station on its next orbit.
  • 1.7K
  • 22 Nov 2022
Topic Review
Propellant Depot
An orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that have been proposed for enabling infrastructure-based space exploration. Many different depot concepts exist depending on the type of fuel to be supplied, location, or type of depot which may also include a propellant tanker that delivers a single load to a spacecraft at a specified orbital location and then departs. In-space fuel depots are not necessarily located near or at a space station. Potential users of in-orbit refueling and storage facilities include space agencies, defense ministries and communications satellite or other commercial companies. Satellite servicing depots would extend the lifetime of satellites that have nearly consumed all of their orbital maneuvering fuel and are likely placed in a geosynchronous orbit. The spacecraft would conduct a space rendezvous with the depot, or vice versa, and then transfer propellant to be used for subsequent orbital maneuvers. In 2011, Intelsat showed interest in an initial demonstration mission to refuel several satellites in geosynchronous orbit, but all plans have been since scrapped. A low earth orbit (LEO) depot's primary function would be to provide propellant to a transfer stage headed to the moon, Mars, or possibly a geosynchronous orbit. Since all or a fraction of the transfer stage propellant can be off-loaded, the separately launched spacecraft with payload and/or crew could have a larger mass or use a smaller launch vehicle. With a LEO depot or tanker fill, the size of the launch vehicle can be reduced and the flight rate increased—or, with a newer mission architecture where the beyond-Earth-orbit spacecraft also serves as the second stage, can facilitate much larger payloads—which may reduce the total launch costs since the fixed costs are spread over more flights and fixed costs are usually lower with smaller launch vehicles. A depot could also be placed at Earth-Moon Lagrange point 1 (EML-1) or behind the Moon at EML-2 to reduce costs to travel to the moon or Mars. Placing a depot in Mars orbit has also been suggested.
  • 1.7K
  • 22 Nov 2022
Topic Review
Long-Term Space Nutrition
Nutrition has many important functions in space travel, from providing enough nutrients and meeting the metabolic needs of a healthy body to enhancing an individual’s emotional well-being. Nutrition also plays a key role in offsetting many negative effects of space travel, such as radiation exposure, immune deficiency, oxidative stress, and bone and muscle loss.
  • 1.7K
  • 30 Jan 2022
Topic Review
Thermal Management System
In gas turbine engines, Thermal Management (TM) is a concept of utilising the engine fluid systems to extract the excess heat generated within the various components and systems of the engine as well as employing the extracted heat for multiple functions that would improve the engine’s performance.
  • 1.7K
  • 14 Jan 2022
Topic Review
Balloon (Aeronautics)
In aeronautics, a balloon is an unpowered aerostat, which remains aloft or floats due to its buoyancy. A balloon may be free, moving with the wind, or tethered to a fixed point. It is distinct from an airship, which is a powered aerostat that can propel itself through the air in a controlled manner. Many balloons have a basket, gondola, or capsule suspended beneath the main envelope for carrying people or equipment (including cameras and telescopes, and flight-control mechanisms).
  • 1.6K
  • 27 Oct 2022
Topic Review
Alternative Aviation Fuels/Pathways
The Paris Agreement’s objectives related to climate change put aviation under great pressure and environmental inspection. In particular, the aviation industry is committed to achieving a 50% reduction in CO2 emissions by 2050 compared to 2005 levels. A shift to alternative aviation fuels seems imperative. The International Air Transport Association (IATA) has identified the production of drop-in sustainable liquid fuels (SAFs) as the most promising strategy, at least short term, to reduce the environmental impact of the sector.
  • 1.6K
  • 03 Mar 2023
Topic Review
Communications of UAS Traffic Management
A UAS traffic management (UTM) system requires that each UAV be able to see and be seen; therefore, the communication channel becomes crucial. In the last five years, state-of-the-art research has focused on three types of communication: ADS-B, ADS-B-like communication, and Remote ID. ADS-B is the legacy system currently used in manned flights and has been mandatory since 2020. Similarly, the ADS-B-like system works similarly to ADS-B but uses different types of wireless communication technology such as 4G, XBee, and APRS (automatic packet reporting system). However, Remote ID is a new standard established, based on Bluetooth/Wi-Fi technology that fulfills the requirement for current UTM operations. The communications in UTM can be categorized into ADS-B, Remote ID, and ADS-B-like systems. The information presented here consist of definition, data format, technology, and research application.
  • 1.6K
  • 14 Mar 2022
Topic Review
Fluidic Thrust Vectoring in Jet Engine Nozzles
Thrust vectoring innovations are demonstrated ideas that improve the projection of aerospace power with enhanced maneuverability, control effectiveness, survivability, performance, and stealth. Thrust vector control systems following a variety of concepts have been considered for modern aircraft and missiles to enhance their military performance. Short Take-off and Landing (STOL) and control effectiveness at lower aircraft speeds can be achieved by employing Fluidic Thrust Vectoring Control (FTVC).
  • 1.6K
  • 10 Aug 2023
Topic Review
Structural Health Monitoring Systems
Structural health monitoring (SHM) is a rapidly evolving field, and there is a vast literature covering several topics that are related to this field. This entry is focused on the analysis of the state of the art of sensors for guided ultrasonic waves for the detection and localization of impacts for structural health monitoring (SHM).
  • 1.6K
  • 06 May 2021
Topic Review
RAF Cardington
Royal Air Force Cardington or more simply RAF Cardington is a former Royal Air Force Royal Air Force station in Bedfordshire, England , with a long and varied history, particularly in relation to airships and balloons. Most of the former RAF station is in the parish of Eastcotts, as is the settlement of Shortstown.
  • 1.5K
  • 29 Nov 2022
Topic Review
Studied Space Shuttle Variations and Derivatives
During the lifetime of NASA's Space Shuttle, Rockwell International and many other organizations studied different Space Shuttle variations and derivatives. These studies included different ways to increase shuttle payload capability, crew capacity, and developing standalone reusable launch vehicles. A large focus of the program was towards new shuttle boosters and an upgrades to the external tank but also looked to expand NASA's ability to launch deep space missions and build large modular space stations. Many of these concepts and studies would shape the concepts and programs of the 2000s such as Constellation, Orbital Space Plane Program, and Artemis program.
  • 1.5K
  • 08 Oct 2022
Topic Review
Boom Technology Overture
The Boom Technology Overture is a Mach 2.2 (1,300 kn; 2,300 km/h), 55-passenger supersonic transport with 4,500 nmi (8,300 km) of range, which is proposed to be introduced in 2025–2027 by Boom Technology. With 500 viable routes, there could be a market for 1,000 supersonic airliners with business class fares. It had gathered 76 commitments by December 2017. It would keep the delta wing configuration of Concorde but would be built with composite materials. It would be powered by three dry 15,000–20,000 lbf (67–89 kN) turbofans, a derivative or a clean-sheet design were to be selected in 2019.
  • 1.4K
  • 21 Nov 2022
Topic Review
List of Starship Flights
Prototypes of the upper stage of the SpaceX Starship have been flown nine times. Designed and operated by private manufacturer SpaceX, the flown prototypes of Starship have been Starhopper, SN5, SN6, SN8, SN9, SN10, SN11, and SN15. Starship is planned to be a fully reusable super heavy-lift launch vehicle and unusual for previous launch vehicle and spacecraft designs, the upper stage of Starship is intended to function both as a second stage to reach orbital velocity on launches from Earth, and also be used in outer space as an on-orbit long-duration spacecraft.
  • 1.4K
  • 02 Dec 2022
Topic Review
Acoustic Metamaterials in Aeronautics
Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. The potential of metamaterial-based technologies has recently caught the interest of the aeronautics community. Their effect in the presence of realistic flows in the surrounding domains, with boundary layer, turbulence, is currently a hot research topic. The interaction with flow requires a careful design of the metamaterial to avoid detrimental effects and enabling the device maximum capabilities in aeronautics.
  • 1.4K
  • 25 Jun 2021
Topic Review
Unmanned NASA Missions
Following is a sampling of some of NASA's past and present programs excluding manned spacecraft. The years in brackets are for first and latest launching. A program is a number of flights or missions with the same kind of spacecraft, therefore the name of the program and the name of the spacecraft used will often be the same. In all, NASA have made more than 1,000 unmanned missions into Earth orbit or beyond.
  • 1.3K
  • 23 Oct 2022
Topic Review
Balloon Satellite
A balloon satellite (also occasionally referred to as a "satelloon", which is a trademarked name owned by Gilmore Schjeldahl's G.T. Schjeldahl Company) is a satellite that is inflated with gas after it has been put into orbit.
  • 1.3K
  • 17 Oct 2022
Topic Review
Gravity Field and Steady-State Ocean Circulation Explorer
The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) was the first of ESA's Living Planet Programme satellites intended to map in unprecedented detail the Earth's gravity field. The spacecraft's primary instrumentation was a highly sensitive gravity gradiometer consisting of three pairs of accelerometers which measured gravitational gradients along three orthogonal axes. Launched on 17 March 2009, GOCE mapped the deep structure of the Earth's mantle and probed hazardous volcanic regions. It brought new insight into ocean behaviour; this in particular, was a major driver for the mission. By combining the gravity data with information about sea surface height gathered by other satellite altimeters, scientists were able to track the direction and speed of geostrophic ocean currents. The low orbit and high accuracy of the system greatly improved the known accuracy and spatial resolution of the geoid (the theoretical surface of equal gravitational potential on the Earth). The satellite's unique arrow shape and fins helped keep GOCE stable as it flew through the thermosphere at a comparatively low altitude of 255 kilometres (158 mi). Additionally, an ion propulsion system continuously compensated for the variable deceleration due to air drag without the vibration of a conventional chemically powered rocket engine, thus limiting the errors in gravity gradient measurements caused by non-gravitational forces and restoring the path of the craft as closely as possible to a purely inertial trajectory. After running out of propellant, the satellite began dropping out of orbit and made an uncontrolled reentry on 11 November 2013.
  • 1.3K
  • 02 Nov 2022
Topic Review
Satellite Navigation Signal Authentication Principles and Technical Architecture
As the Global Navigation Satellite System (GNSS) is widely used in all walks of life, the signal structure of satellite navigation is open, and the vulnerability to spoofing attacks is also becoming increasingly prominent, which will seriously affect the credibility of navigation, positioning, and timing (PNT) services. Satellite navigation signal authentication technology is an emerging technical means of improving civil signal anti-spoofing on the satellite navigation system side, and it is also an important development direction and research focus of the GNSS. 
  • 1.3K
  • 12 Apr 2023
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