PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Configuration design method of mega constellation for low earth orbit observation

Configuration design method of mega constellation for low earth orbit observation
2024-08-05
(Press-News.org)

First, satellites in the mega constellation are categorized and the constellation design based on different satellite division is proposed. Satellites in the mega constellation are divided into 2 types, namely, the basic satellites and the accompanying satellites. All basic satellites that are surrounded by accompanying satellites are evenly distributed globally, and they have the same subsatellite trajectory. A basic satellite and its accompanying satellites are defined as a satellite group. The constellation is composed of many satellite groups, as shown in Fig. 1.

As for basic satellites, the semimajor axis a of regression orbit can be numerically solved considering (1) that regression orbit requires a satellite flies R times around Earth in D days and (2) that the influence of J2 perturbation force of an orbit is considered. Assuming that the ground coverage width of a satellite group is d, the number of basic orbital plane is Nt = ceiling(2πRe/d) where ceiling(⋅) is the round up function. Assuming that the maximum response time to complete Earth observation mission required by the user is mt and the orbital plane is evenly divided according to the orbital period T, the number of basic satellites in each orbital plane is Nn = ceiling(T/mt). Based on above analysis, input the i, e, and ω of the constellation and Q = R/D, then the basic satellites constellation is designed.

As for accompanying satellites, they have the semimajor axis with basic satellites. According to the Clohessy-Wiltshire equation, the relative motion trajectory between the basic satellites and the accompanying satellites is an ellipse. Then, considering that the position vectors at the initial time and T/2 relative to the basic satellite is oppositive, the orbital elements of the first accompanying satellites can be solved. Assuming that the imaging width of a single satellite is sd, the number of accompanying satellites in a satellite group is Na = ceiling(d/sd - 1). Divide the trajectory of the first accompanying satellite relative to basic satellite orbital coordinate system in chronological order, extract the position vectors of all equal points under the orbital system, and use these as the position vectors of other accompanying satellites under the basic satellite orbital system at initial time.

Combining the basic and accompanying satellites’ orbits, the configuration of mega constellation is obtained.

 

Fig. 1. Orbital distribution of LEO mega constellation.

 

Then, the orbit parameters of satellite and its companions are set as initial values, and the precise orbits under the High Precision Orbit Propagator model are solved in the neighborhood by using the Nondominated Sort Particle Swarm Optimization algorithm. Transform the orbital elements of any basic satellite into position and velocity information, which is recorded as {pxpq, pypq, pzpq, vxpq, vypq, vzpq}. Add an increment to build their neighborhood, which can be expressed to {Δpxpq, Δpypq, Δpzpq, Δvxpq, Δvypq, Δvzpq}. The optimization variable of accompanying satellite orbit is the position and velocity increment of all basic satellites. The optimization objective f1 for the basic satellite configuration is to minimize the absolute difference between the ascending and descending nodes of any basic satellite bspq in cycle i, and the ascending and descending nodes of bs1q as much as possible. The optimization objective f2 of the accompanying satellite is to keep the relative position as close as possible under the basic satellite orbit system at multiple subsequent motion periods. Optimization iteration process involves continuously approaching the Pareto front. In practice, find all nondominant solutions of the initial individual as the optimal solution set. Calculate 2 optimization objectives of everyone in sequence, and use the nearest global nondominated individual and own historical nondominated individual as learning objects. Update individual optimization variables and variable increments based on population information, individual experience, and self-inertia, as shown in Fig. 10. Then calculate the f1 and f2 of newly generated individuals again, and regenerate the global Pareto front and individual historical Pareto front. After a fixed number of cycles or objective function is less than the threshold, the iteration ends and the global Pareto front can be obtained. At this point, the final constellation configuration can be selected based on user preferences or linear superposition of f1 and f2.

 

Fig. 10. Individual update process.

 

Finally, the correctness of the configuration design method is verified by numerical simulation. In the simulation, set the constellation orbital inclination as 66°, eccentricity as 0, argument of perigee as 0, simulation time as 1 d, set regression coefficient Q = 15, initial ascending node as 0, initial MA as 0, imaging width of a satellite group as 1500 km, imaging width of single satellite as 140 km, and maximum working time of single satellite to orbit single circle as 35 min. During the optimization, it can be observed that the approximation speed of the Pareto front in the first 100 generations is extremely fast. As the number of iteration increases, the variation of the Pareto front gradually decreases and eventually becomes stable. In the final generation of nondominated solutions, we select the individual of f1 = 1.981 and f2 = 9516.482 as the final solution, and the constellation configuration is shown in Fig. 15. The constellation has a total of 891 satellites, of which 81 basic satellites are evenly distributed, with 10 accompanying satellites evenly distributed around each basic satellite. A total of 810 accompanying satellites can achieve collaborative observation of any position outside the polar region within 35 min.

 

Fig. 15. Final LEO mega constellation configuration.

END


[Attachments] See images for this press release:
Configuration design method of mega constellation for low earth orbit observation Configuration design method of mega constellation for low earth orbit observation 2 Configuration design method of mega constellation for low earth orbit observation 3

ELSE PRESS RELEASES FROM THIS DATE:

Sometimes it hurts to think

2024-08-05
If somebody complains that it hurts to think, they may be onto something, as mental exertion appears to be associated with unpleasant feelings in many situations, according to research published by the American Psychological Association. “Managers often encourage employees, and teachers often encourage students, to exert mental effort. On the surface, this seems to work well: Employees and students do often opt for mentally challenging activities,” said senior author Erik Bijleveld, PhD, of Radboud University. “From this, you may be tempted to conclude that ...

FAU lands $1.3M NSF grant to boost dryland soil quality amid climate stressors

FAU lands $1.3M NSF grant to boost dryland soil quality amid climate stressors
2024-08-05
Drylands, found across every continent, cover about 45% of the Earth's land surface and support 38% of the human population. In these regions, precipitation is low and evaporation rates are typically high, leading to an arid or semi-arid climate. Due to scarce water resources and sparse vegetation, drylands present formidable challenges for agriculture and human habitation. As the climate continues to warm, drylands are rapidly expanding.  A particularly urgent problem in drylands is climate-driven soil degradation, which affects about 33% of the planet’s land surface. Drylands host ...

Self-powered pump harnesses light and chemistry to target, capture pollutants

Self-powered pump harnesses light and chemistry to target, capture pollutants
2024-08-05
Dartmouth researchers have developed a self-powered pump that uses natural light and chemistry to target and remove specific water pollutants, according to a new report in the journal Science. As water enters the pump, a wavelength of light activates a synthetic molecular receptor designed to bond to negatively charged ions, or anions, a class of pollutants linked to metabolic disruptions in plants and animals. A second wavelength deactivates the receptors as water exits the pump and causes them to release the ...

Heart transplant list doesn’t rank kids by medical need, Stanford Medicine-led study finds

Heart transplant list doesn’t rank kids by medical need, Stanford Medicine-led study finds
2024-08-05
The method used across the United States to wait-list children for heart transplants does not consistently rank the sickest patients first, according to a new study led by Stanford Medicine experts.  The study will publish online Aug. 5 in the Journal of the American College of Cardiology. Adding nuance to the wait-list system by accounting for more health factors could reduce children’s risk of dying while they await donor hearts, according to the study’s authors. A revision to the way donor hearts are assigned is already in process. The study adds evidence for why it is needed, they ...

Advancing towards a novel, highly accurate method for cervical cancer screening

Advancing towards a novel, highly accurate method for cervical cancer screening
2024-08-05
Cervical cancer is a highly prevalent cancer, with approximately 500,000 new cases diagnosed each year. Shockingly, the number of individuals diagnosed with precursor lesions in the cervix—also known as cervical intraepithelial neoplasia (CIN)—is 20 times higher. As with many potentially malignant conditions, early diagnosis of cervical cancer can make all the difference in a patient’s life in terms of treatment outcomes. For this, developing effective, convenient, and easily available screening protocols for CIN and cervical cancer is of paramount importance. Currently, the two ...

First measurement of electron- and muon-neutrino interaction rates at the highest energy ever detected from an artificial source

First measurement of electron- and muon-neutrino interaction rates at the highest energy ever detected from an artificial source
2024-08-05
Neutrinos are fundamental particles in the Standard Model of particle physics, notable for their extremely small masses and weak interactions with matter. They are important for answering fundamental questions about the universe, including why particles have mass and why there is more matter than antimatter. Despite being abundant, their weak interactions make their detection difficult, and hence they are called “ghost particles.” At any given moment, numerous neutrinos freely pass through the Earth and our bodies, which originate from the Sun or cosmic rays. Understanding their rare interactions with matter is crucial for obtaining a more complete picture ...

Breakthrough: Natural bacteria compound offers safe skin lightening

Breakthrough: Natural bacteria compound offers safe skin lightening
2024-08-05
Melanin protects the skin—the body's largest organ and a vital component of the immune system—from the damaging effects of ultraviolet (UV) radiation. When the skin is exposed to UV radiation, melanin production is stimulated in melanocytes, with tyrosinase playing a key role in the biosynthetic pathway. However, disruptions in this pathway caused by UV exposure or aging can lead to excess melanin accumulation, resulting in hyperpigmentation. To address this, tyrosinase inhibitors that suppress melanin synthesis have become valuable in the cosmetic industry. Unfortunately, some of these compounds, ...

Study analyzes potato-pathogen ‘arms race’ after Irish famine

Study analyzes potato-pathogen ‘arms race’ after Irish famine
2024-08-05
In an examination of the genetic material found in historic potato leaves, North Carolina State University researchers reveal more about the tit-for-tat evolutionary changes occurring in both potato plants and the pathogen that caused the 1840s Irish potato famine.  The study used a targeted enrichment sequencing approach to simultaneously examine both the plant’s resistance genes and the pathogen’s effector genes – genes that help it infect hosts – in a first-of-its-kind analysis. “We use small pieces of historic leaves with the pathogen ...

Seismic detectors measure soil moisture using traffic noise

2024-08-05
Caltech researchers have developed a new method to measure soil moisture in the shallow subterranean region between the surface and underground aquifers. This region, called the vadose zone, is crucial for plants and crops to obtain water through their roots. However, measuring how this underground moisture fluctuates over time and between geographical regions has traditionally relied on satellite imaging, which only gives low-resolution averages and cannot penetrate below the surface. Additionally, moisture within the vadose zone changes rapidly—a thunderstorm can saturate a region that dries ...

State-level, out-of-pocket insulin caps do not substantially increase utilization, study finds

2024-08-05
AURORA, Colo. (August 5, 2024) – In a first-of-its-kind study, a cohort of researchers, led by the University of Colorado Anschutz Medical Campus, evaluated the effects of state-level insulin out-of-pocket costs across states and payers and over time. The team found that state-level caps on insulin out-of-pocket costs do not significantly increase insulin claims for patients with Type 1 or patients using insulin to manage Type 2 diabetes. Study results could help inform policies aimed at better delivering cost-capped insulin to patients struggling with insulin affordability. Approximately ...

LAST 30 PRESS RELEASES:

Reality check: making indoor smartphone-based augmented reality work

Overthinking what you said? It’s your ‘lizard brain’ talking to newer, advanced parts of your brain

Black men — including transit workers — are targets for aggression on public transportation, study shows

Troubling spike in severe pregnancy-related complications for all ages in Illinois

Alcohol use identified by UTHealth Houston researchers as most common predictor of escalated cannabis vaping among youths in Texas

Need a landing pad for helicopter parenting? Frame tasks as learning

New MUSC Hollings Cancer Center research shows how Golgi stress affects T-cells' tumor-fighting ability

#16to365: New resources for year-round activism to end gender-based violence and strengthen bodily autonomy for all

Earliest fish-trapping facility in Central America discovered in Maya lowlands

São Paulo to host School on Disordered Systems

New insights into sleep uncover key mechanisms related to cognitive function

USC announces strategic collaboration with Autobahn Labs to accelerate drug discovery

Detroit health professionals urge the community to act and address the dangers of antimicrobial resistance

3D-printing advance mitigates three defects simultaneously for failure-free metal parts 

Ancient hot water on Mars points to habitable past: Curtin study

In Patagonia, more snow could protect glaciers from melt — but only if we curb greenhouse gas emissions soon

Simplicity is key to understanding and achieving goals

Caste differentiation in ants

Nutrition that aligns with guidelines during pregnancy may be associated with better infant growth outcomes, NIH study finds

New technology points to unexpected uses for snoRNA

Racial and ethnic variation in survival in early-onset colorectal cancer

Disparities by race and urbanicity in online health care facility reviews

Exploring factors affecting workers' acquisition of exercise habits using machine learning approaches

Nano-patterned copper oxide sensor for ultra-low hydrogen detection

Maintaining bridge safer; Digital sensing-based monitoring system

A novel approach for the composition design of high-entropy fluorite oxides with low thermal conductivity

A groundbreaking new approach to treating chronic abdominal pain

ECOG-ACRIN appoints seven researchers to scientific committee leadership positions

New model of neuronal circuit provides insight on eye movement

Cooking up a breakthrough: Penn engineers refine lipid nanoparticles for better mRNA therapies

[Press-News.org] Configuration design method of mega constellation for low earth orbit observation