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

Where is that spacecraft?

Statistically measuring uncertainty for space surveillance

2014-09-22
(Press-News.org) Philadelphia, PA—Space surveillance is inherently challenging when compared to other tracking environments due to various reasons, not least of which is the long time gap between surveillance updates. "Unlike the air and missile defense environments where objects are frequently observed, the space surveillance environment data is starved, with many objects going several orbital periods between observations," according to researcher Joshua Horwood. "Thus, it is more challenging to predict the future location of these sparsely-seen objects and they have a tendency to get lost using traditional methods. A new way of tracking them, the Gauss von Mises (GVM) distribution, has improved predictive capabilities that permit one to more effectively maintain custody of infrequently-observed space objects."

In a paper published in July in the SIAM/ASA Journal on Uncertainty Quantification, authors Horwood and Aubrey Poore, both of Numerica Corporation, propose a more statistically rigorous treatment of uncertainty in the near-Earth space environment than currently available. The method proposed is a new class of multivariate probability density functions, called the Gauss von Mises (GVM) family of distributions.

"By more faithfully representing the uncertainty in a space object's orbit, the GVM distribution allows one to more accurately predict the future locations of satellites and debris," says Horwood. "Uncertainty propagation using the GVM distribution can be achieved at a computational cost commensurate with traditional methods and can maintain a proper characterization of the uncertainty for up to eight times as long."

It is important to study uncertainty in the space surveillance tracking environment in order to protect space assets and maintain awareness of potentially adversarial space deployments. The proper characterization of uncertainty enables us to allocate resources in order to gain as much information about the system as possible, and detect satellite maneuvers. Better uncertainty quantification also helps us track and look for close approaches between any two space objects, a process called conjunction analysis.

Horwood explains further with an example, "In the problem of conjunction analysis, the use of the GVM distribution can provide a more reliable probability of collision and allows conjunction assessments further into the future. This translates into fewer false alarms and hence fewer expensive maneuver operations that have to be performed on operational spacecraft."

In order to quantify uncertainty, proper characterization of a space object's full state probability density function (PDF) is required to faithfully represent the statistical errors. The GVM distribution approach is supported by a suite of next-generation algorithms for uncertainty propagation, data association, space catalog maintenance, and other space situational awareness functions. What distinguishes the GVM distribution is that it is defined on a cylindrical manifold, and such coordinates, used in conjunction with the GVM distribution, can provide a statistically rigorous treatment of uncertainty needed for orbit determination and tracking.

Methods proposed in this paper will be beneficial for studying various aspects of future space surveillance. "A quantification of the uncertainties in space surveillance is a prerequisite for robustly tracking hundreds of thousands of space objects that are expected in the future," says Horwood. "This involves various levels of research including sensor-level processing (to improve the characteristics of the measurement errors and biases), propagation of uncertainty, dynamics and space environment modeling, inverse problems such as statistical orbit determination, and high performance computing to serve the growing space catalog."

INFORMATION: Source Article

Gauss von Mises Distribution for Improved Uncertainty Realism in Space Situational Awareness http://epubs.siam.org/doi/abs/10.1137/130917296 Joshua T. Horwood and Aubrey B. Poore

About the Authors

Joshua Horwood and Aubrey Poore are researchers at Numerica Corporation in Loveland, Colorado.


ELSE PRESS RELEASES FROM THIS DATE:

Neurosurgery tackles past, current and future concepts of sports concussion

2014-09-22
September 22, 2014 - An estimated 1.68 to 3.8 million sports-related concussions occur in the United States each year, and there are likely a significant number that go unreported. Current Concepts in Sports Concussion is a comprehensive, 16-article supplement of Neurosurgery, official journal of the Congress of Neurological Surgeons. Chicago-area neurosurgeon Gail Rosseau, MD, the lead guest editor, is well known for her longtime commitment to sports-related head injury prevention, and serves on the Board of Directors of USA Football and ThinkFirst. Additional guest editors ...

Comprehensive Neurosurgery supplement covers sports-related concussions

2014-09-22
September 22, 2014 - Neurosurgeons have treated head and spinal sports injuries since the specialty was formed in the early 20th century, with formal efforts to mitigate these injuries dating back to 1931. Current Concepts in Sports Concussion is a comprehensive, 16-article supplement of Neurosurgery, official journal of the Congress of Neurological Surgeons, published by Lippincott Williams & Wilkins, part of Wolters Kluwer Health. The supplement includes a detailed, fascinating history of concussion treatment and research. The lead guest editor is Chicago-area neurosurgeon ...

Communication without detours

Communication without detours
2014-09-22
Certain nerve cells take a shortcut for the transmission of information: signals are not conducted via the cell`s center, but around it like on a bypass road. The previously unknown nerve cell shape is now presented in the journal "Neuron" by a research team from Heidelberg, Mannheim and Bonn. Nerve cells communicate by using electrical signals. Via widely ramified cell structures—the dendrites—, they receive signals from other neurons and then transmit them over a thin cell extension—the axon—to other nerve cells. Axon and dendrites are usually interconnected by the ...

The accelerator of molecular motors

The accelerator of molecular motors
2014-09-22
To their surprise, it turned out to be an old acquaintance: a certain module of the familiar protein Pex22p, which has hitherto always been considered an anchor protein. The researchers report their findings in PLoS One. Essential: importing enzymes into peroxisome Peroxisomes are of vital importance for the enzymatic degradation of long-chain fatty acids and cellular toxins. In order for them to fulfil this function, the relevant enzymes have to be imported into the peroxisomes first. The bulk is brought into a peroxisome by the import receptor Pex5p. That receptor, ...

Why do leaves change color in the fall? (video)

Why do leaves change color in the fall? (video)
2014-09-22
WASHINGTON, Sept. 22, 2014 — It's the first day of autumn, and the telltale signs are here: crisp weather, pumpkin spice lattes and, most importantly, the leaves are changing colors. Ever wonder why some leaves turn red, others yellow and some just turn brown? We'll tell you all about the chemistry behind this seasonal spectacle in the latest Reactions episode. Learn all about it at https://www.youtube.com/watch?v=X0nWmTeQPfo. Subscribe to the series at Reactions YouTube, and follow us on Twitter @ACSreactions to be the first to see our latest videos. INFORMATION:The ...

Finding hints of gravitational waves in the stars

2014-09-22
Scientists have shown how gravitational waves—invisible ripples in the fabric of space and time that propagate through the universe—might be "seen" by looking at the stars. The new model proposes that a star that oscillates at the same frequency as a gravitational wave will absorb energy from that wave and brighten, an overlooked prediction of Einstein's 1916 theory of general relativity. The study, which was published today in the Monthly Notices of the Royal Astronomical Society: Letters, contradicts previous assumptions about the behavior of gravitational waves. "It's ...

New study finds 34 percent of severely injured patients undertriaged in the United States

2014-09-22
According to the American College of Surgeons' Committee on Trauma, patients with severe injuries should be treated at level I or level II trauma centers. Those centers have the resources to provide the best care for those patients. But 1 out of 3 major trauma patients in 2010 actually received their treatment at lower-level trauma centers or nontrauma centers, according to a new study from the Center for Pediatric Trauma Research and the Center for Injury Research and Policy at Nationwide Children's Hospital. Those patients are "undertriaged." The ACS' Committee on Trauma ...

Mothers of children with autism less likely to have taken iron supplements

2014-09-22
(SACRAMENTO, Calif.) —Mothers of children with autism are significantly less likely to report taking iron supplements before and during their pregnancies than the mothers of children who are developing normally, a study by researchers with the UC Davis MIND Institute has found. Low iron intake was associated with a five-fold greater risk of autism in the child if the mother was 35 or older at the time of the child's birth or if she suffered from metabolic conditions such as obesity hypertension or diabetes. The research is the first to examine the relationship between ...

Research evaluates neurodevelomental and medical outcomes in single family room NICU

2014-09-22
The prevalence of preterm birth – the birth of an infant prior to 37 weeks of pregnancy – is a significant health problem that has increased over the past two decades. According to the Centers for Disease Control and Prevention (CDC), preterm birth affects nearly 500,000 babies each year, or one of every eight born in the U.S. While medical care has improved survival rates for preterm infants, questions remain about ways to positively impact the neurodevelopmental outcomes of preterm infants. Research led by Barry M. Lester, PhD, director of the Brown Center for the ...

E-cigarettes unhelpful in smoking cessation among cancer patients

2014-09-22
In a new study of cancer patients who smoke, those using e-cigarettes (in addition to traditional cigarettes) were more nicotine dependent and equally or less likely to have quit smoking traditional cigarettes than non-users. Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the findings raise doubts about the potential benefits of e-cigarettes for helping cancer patients give up smoking. Because of the risks of persistent smoking, all cancer patients who smoke should be advised to quit. But the rising use of e-cigarettes has raised ...

LAST 30 PRESS RELEASES:

Pink skies

Monkeys are world’s best yodellers - new research

Key differences between visual- and memory-led Alzheimer’s discovered

% weight loss targets in obesity management – is this the wrong objective?

An app can change how you see yourself at work

NYC speed cameras take six months to change driver behavior, effects vary by neighborhood, new study reveals

New research shows that propaganda is on the rise in China

Even the richest Americans face shorter lifespans than their European counterparts, study finds

Novel genes linked to rare childhood diarrhea

New computer model reveals how Bronze Age Scandinavians could have crossed the sea

Novel point-of-care technology delivers accurate HIV results in minutes

Researchers reveal key brain differences to explain why Ritalin helps improve focus in some more than others

Study finds nearly five-fold increase in hospitalizations for common cause of stroke

Study reveals how alcohol abuse damages cognition

Medicinal cannabis is linked to long-term benefits in health-related quality of life

Microplastics detected in cat placentas and fetuses during early pregnancy

Ancient amphibians as big as alligators died in mass mortality event in Triassic Wyoming

Scientists uncover the first clear evidence of air sacs in the fossilized bones of alvarezsaurian dinosaurs: the "hollow bones" which help modern day birds to fly

Alcohol makes male flies sexy

TB patients globally often incur "catastrophic costs" of up to $11,329 USD, despite many countries offering free treatment, with predominant drivers of cost being hospitalization and loss of income

Study links teen girls’ screen time to sleep disruptions and depression

Scientists unveil starfish-inspired wearable tech for heart monitoring

Footprints reveal prehistoric Scottish lagoons were stomping grounds for giant Jurassic dinosaurs

AI effectively predicts dementia risk in American Indian/Alaska Native elders

First guideline on newborn screening for cystic fibrosis calls for changes in practice to improve outcomes

Existing international law can help secure peace and security in outer space, study shows

Pinning down the process of West Nile virus transmission

UTA-backed research tackles health challenges across ages

In pancreatic cancer, a race against time

Targeting FGFR2 may prevent or delay some KRAS-mutated pancreatic cancers

[Press-News.org] Where is that spacecraft?
Statistically measuring uncertainty for space surveillance