Low Earth Orbit Research Papers (original) (raw)

Research on global gravity field recovery from satellite missions such as CHAMP and GRACE was initiated at the Astronomical Institute of the University of Bern (AIUB, Switzerland) in the year 2006. Since September 2007, the activities... more

Research on global gravity field recovery from satellite missions such as CHAMP and GRACE was initiated at the Astronomical Institute of the University of Bern (AIUB, Switzerland) in the year 2006. Since September 2007, the activities were extended in the framework of the project Satellite Geodesy sponsored by the Institute for Advanced Study (IAS) of the Technical University of Munich

Knowledge of the observable properties of orbital debris is necessary to validate debris models for both the low Earth orbit (LEO) and the geosynchronous Earth orbit (GEO). Current methods determine the size and mass of orbital debris... more

Knowledge of the observable properties of orbital debris is necessary to validate debris models for both the low Earth orbit (LEO) and the geosynchronous Earth orbit (GEO). Current methods determine the size and mass of orbital debris based on knowledge or assumption of the material type of the piece. Improvement in the knowledge of material is the goal of the

Remote measurements of the atmospheric state can be performed by radio occultation between satellites, a GPS satellite transmitting a radio signal to a receiving low Earth orbit (LEO) satellite, or between LEO satellites. The bending... more

Remote measurements of the atmospheric state can be performed by radio occultation between satellites, a GPS satellite transmitting a radio signal to a receiving low Earth orbit (LEO) satellite, or between LEO satellites. The bending angle of the traversing optical ray can be measured by detecting the Doppler shift of radio signals. The bending angle is an integrated measure of the refractive index in the atmosphere traversed by the optical ray. With a time series (profile) of the bending angle, it is possible to perform an inversion to obtain the refractive index. Various techniques for the retrieval of the bending profile already exist. The most recent methods have solved the problem of multipath, i.e., when the atmosphere allows several rays to exist simultaneously. The paper presents a new method for the reconstruction of bending angle as a single-valued function of impact parameter from complex radio occultation signal under multipath propagation conditions. The method utilizes the assumption of spherical symmetry of refractivity, i.e., n(?) = n(r), and the principle of synthetic aperture, thus allowing sub-Fresnel resolution. A distinctive feature of the method, as compared to previously known methods, is direct applicability for arbitrary orbits of transmitting and receiving satellites, without intermediate propagation of complex electromagnetic field to circle or straight line. This comes at the expense of impossibility to reduce the method to a FFT. The method can be useful for inverting radio occultation signals and for validation of other radio holographic methods.

The commercialization of space has resulted in a significant increase in the frequency of spacecraft, which is adding to the already large number of objects in orbit. Therefore, future and present missions are at risk from space debris.... more

The commercialization of space has resulted in a significant increase in the frequency of spacecraft, which is adding to the already large number of objects in orbit. Therefore, future and present missions are at risk from space debris. Most of these spacecraft in orbit have very limited means of mitigation control systems. As a result, certain international regulations are imposed to obtain a license for a spacecraft for launch purposes. The necessity of a feasible debris mitigation technique enables future space missions to be safe and sustainable. This review sheds light on the drag augmentation devices such as dragsail, which can provide an effective means for accelerating the deorbiting process during the EOL phase, making space safe and sustainable without the risk of space debris.

Since its launch into low-Earth orbit in June 1999, the mission of the Far Ultraviolet Spectroscopic Explorer (FUSE) has been to obtain high resolution far ultraviolet (905-1187 Å) spectra of a wide variety of astronomical sources. In... more

Since its launch into low-Earth orbit in June 1999, the mission of the Far Ultraviolet Spectroscopic Explorer (FUSE) has been to obtain high resolution far ultraviolet (905-1187 Å) spectra of a wide variety of astronomical sources. In late 2001, two of FUSE's four reaction wheels failed, compromising the ability to control spacecraft pointing. The FUSE Project adapted by developing a

Various proposed space elevators may bypass the financial and environmental limits on rocket technology, but all have their own problems. A Low-Earth-Orbit, LEO, rotovator-based space-elevator version called 'sling-on-a-ring' may... more

Various proposed space elevators may bypass the financial and environmental limits on rocket technology, but all have their own problems. A Low-Earth-Orbit, LEO, rotovator-based space-elevator version called 'sling-on-a-ring' may overcome them. This mass-lifting system uses the spatial stability of an orbital ring, accessorized for transfer and storage of momentum and electrical power. A high-tensile-strength equatorial circum-terra loop of colossal-carbon tube, CCT, fiber has solar-power and station-keeping units and rotating sling modules. Long sling assemblies, ~600 km, periodically descend into the atmosphere to ~13 km. At perigee, the sling rotational tip velocity almost cancels the orbital-ring velocity relative to Earth surface. Split-second timing detaches a ~10 ton payload from an ordinary aircraft and jerks it into space by sling momentum, with the proven specific strength of CCTs now under development. This system eliminates the immense mass in space of other spac...

Economy is a term referring to the set of interrelated production and consumption activities relying on a careful management of available resources. The space resources upon which a robust economy in Earth's orbit can be created are:... more

Economy is a term referring to the set of interrelated production and consumption activities relying on a careful management of available resources. The space resources upon which a robust economy in Earth's orbit can be created are: extremes in temperature, ultra-high vacuum, perpetually available solar power, reduced gravity, data, and remote sensing. Three pillars: technical, economic and policy, with their corresponding responsibilities and ethics will be discussed. Several concepts-from allowing incorporation in Earth's orbit (.leo) to creating a currency from mining solar powered data centers as well as encouraging future growth through standardization and smart use of "touch of space" branding will be proposed. Discussion will also focus on the types of approaches (new insights, processing and reprocessing in space, manufacturing and assembly) that could be used to return the value of space to Earth for economic growth and public benefit. Lessons learned from past commercialization efforts will be reviewed. Traditionally results have been categorized based on fundamental scientific or engineering disciplines; an approach that is effective at highlighting research in a given field. However, it often results in discipline level stove-piping which is counterproductive to commercialization. To overcome this limitation, the concept of Microgravity Verticals is introduced where existing microgravity results have been binned across multiple disciplines based on their relevance to a sector of terrestrial private industry. The Microgravity Verticals are developed to capture in a compressed manner a mix of very diverse values (knowledge, processing) of the microgravity environment through companies who have self identified their interest or intent to mature those technologies for commercial applications and extend the Verticals into the future via microgravity-based solutions relevant to a sector of the private industry aligned with current industry specific roadmaps. A new approach, the Economic Readiness Level (ERL) is proposed that relates technology and investment considerations to supply, demand and capital. To advance on the Economic Readiness Level scale, the technology itself may not necessarily need to mature but the understanding of its economic potential does. Building on these new concepts of Microgravity Verticals and the Economic Readiness Level, this paper further captures and describes key aspects and elements of the machinery of commercialization to create pathways for infusion of private capital that could harvest the resources of space through a robust economy in Earth's orbit and beyond and return value to Earth.

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of LEO space is threatened by runaway collisional cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1 cm... more

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of LEO space is threatened by runaway collisional cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1 cm demands serious attention. A promising proposed solution uses a high power pulsed laser system on the Earth to make plasma jets on the objects, slowing them slightly, and causing them to re-enter and burn up in the atmosphere. In this paper, we reassess this approach in light of recent advances in low-cost, light-weight modular design for large mirrors, calculations of laser-induced orbit changes and in design of repetitive, multi-kilojoule lasers, that build on inertial fusion research. These advances now suggest that laser orbital debris removal (LODR) is the most cost-effective way to mitigate the debris problem. No other solutions have been proposed that address the whole problem of large and small debris. A LODR system will have multiple uses beyond debris removal. International cooperation will be essential for building and operating such a system.

A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced “heartbeat” in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and... more

A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced “heartbeat” in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle events. That climate system response to intricate orbital variations suggests a fundamental interaction of the carbon cycle, solar forcing, and glacial events. Box modeling shows that the interaction of the carbon cycle and solar forcing modulates deep ocean acidity as well as the production and burial of global biomass. The pronounced 405,000-year eccentricity cycle is amplified by the long residence time of carbon in the oceans.

The space sector has grown dramatically in recent years and is now seen as an important growth engine for the global economy. Tourism, mass and mega launches, moon, mars, asteroid missions, and deployment of the Webb observatory were... more

The space sector has grown dramatically in recent years and is now seen as an important growth engine for the global economy. Tourism, mass and mega launches, moon, mars, asteroid missions, and deployment of the Webb observatory were highlightes in 2021. The year 2022 promises to be yet another fantastic sign of the private sector expanding its hold over modern space and enabling Space Industrialization to progress.
The year-on-year global payload deployments increased by 29%, fourteen civilians experienced space tourism, ushering in a new age of space exploration, and international launch attempts reached a record high of 145, mainly owing to SpaceX's Starlink and OneWeb missions. This is unprecedented, and there has never been a more exciting or better time to be part of the global space ecosystem. Influential commercial factors, evolving technologies, and human imagination are driving the new space sector to completely unexplored heights. Furthermore, the explosive growth of the space industry has resulted in large-scale entrepreneurship and exceptional start-up culture.

PRISMA is an ongoing satellite project comprising two satellites. The project constitutes an in-orbit test bed for Guidance, Navigation and Control (GNC) algorithms and sensors for advanced closed-loop formation flying and rendezvous. The... more

PRISMA is an ongoing satellite project comprising two satellites. The project constitutes an in-orbit test bed for Guidance, Navigation and Control (GNC) algorithms and sensors for advanced closed-loop formation flying and rendezvous. The satellites will be launched in a low earth orbit and carry out a series of maneuvering experiments and sensor experiments during a mission time of 8-10 months. Autonomous formation flying in decimeter precision will be demonstrated using relative GPS and Formation Flying RF metrology instruments. Vision based methods using a modified star camera will demonstrate autonomous homing and rendezvous from hundreds of kilometers down to close proximity. Proximity operations based on GPS or optical information shall be demonstrated all the way down to almost physical contact. A new environmentally friendly, non-toxic chemical propulsion system as well as a new MEMS microthruster system will be flight demonstrated.

A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO" - is proposed as a means of solving or bypassing many major problems hindering man's quest to get into space. A fiber-optic ring about the earth... more

A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO" - is proposed as a means of solving or bypassing many major problems hindering man's quest to get into space. A fiber-optic ring about the earth would be an initial testing and developmental stage for the ring systems, while providing cash-flow through a LEO-based, high-band-width, world-wide communication system. A Low-Earth-Orbit-based space-elevator system, "Sling-on-a-Ring," is proposed as the crucial developmental stage of the LEO Archipelago. Being a LEO-based heavy-mass lifter, rather than earth- or GEO-based, it is much less massive and therefore less costly than other proposed space-elevators. With the advent of lower-cost, higher-mass transport to orbit, the options for further space development (e.g., communications, space solar power, radiation dampers, sun shades, and permanent LEO habitation) are greatly expanded. This paper provides an update of the Sling-on-a-Ring concept in terms of new materials, potential applications, and trade-offs associated with an earlier model. The impact of Colossal Carbon Tubes, CCT, a material with high tensile strength, extremely-low density, and other favorable properties and new technologies (e.g., solar-powered lasers, power beaming to near-space and earth, and thermal-control systems) on the development of associated LEO-Ring systems (e.g., "Solar-Shade Rings" and "Power Rings") is also explored. The material's effect on the timeline for the system development indicates the feasibility of near-term implementation of the system (possibly within the decade). The Sling-on-a-Ring can provide a less-expensive, environment-friendly, mode of access to space. This would pave the way (via eventual operation at >1000 tonnes per day by 2050) for large scale development of space-based technologies.

The Sergio Arboleda University is preparing its next satellite mission, named Libertad 2. It will carry out a system of image acquisition as a working tool for researches based on the obtained data. Complete methodologies are often used... more

The Sergio Arboleda University is preparing its next
satellite mission, named Libertad 2. It will carry out a system of image acquisition as a working tool for researches based on the obtained data. Complete methodologies are often used in the development of satellite missions for planning, execution and deployment, for example, the standards of the European Cooperation for Space Standardization; these methodologies, however, do not include technical specifications or requirements for the development of nano-satellites nor for their subsystems. For this reason, this article focuses on the identification of the characteristics, requirements and restrictions, which must be considered in the design of a remote sensing system for satellites under the CubeSat standard, in order to serve as a starting point for the development of the main payload of the Libertad 2 mission.