Connect with us

Science

Two satellites just avoided a head-on smash: How close did they come to disaster? – Phys.org

Published

 on


<div data-thumb="https://scx1.b-cdn.net/csz/news/tmb/2020/twosatellite.jpg" data-src="https://scx2.b-cdn.net/gfx/news/hires/2020/twosatellite.jpg" data-sub-html="The now defunct Infrared Astronomical Telescope was one of the satellites involved in the near-collision. Credit: NASA/JPL“>

<img src="https://scx1.b-cdn.net/csz/news/800/2020/twosatellite.jpg" alt="Two satellites just avoided a head-on smash—how close did they come to disaster?" title="The now defunct Infrared Astronomical Telescope was one of the satellites involved in the near-collision. Credit: NASA/JPL“>
The now defunct Infrared Astronomical Telescope was one of the satellites involved in the near-collision. Credit: NASA/JPL

It appears we have missed another close call between two satellites—but how close did we really come to a catastrophic event in space?

Genius Dog 336 x 280 - Animated

It all began with a series of tweets from LeoLabs, a company that uses radar to track satellites and debris in . It predicted that two obsolete satellites orbiting Earth had a one in 100 chance of an almost direct head-on at 9:39am AEST on 30 January, with potentially devastating consequences.

LeoLabs estimated that the satellites could pass within 15-30m of one another. Neither satellite could be controlled or moved. All we could do was watch whatever unfolded above us.

Collisions in space can be disastrous and can send high-speed debris in all directions. This endangers other satellites, future launches, and especially crewed space missions.

As a point of reference, NASA often moves the International Space Station when the risk of collision is just one in 100,000. Last year the European Space Agency moved one of its satellites when the likelihood of collision with a SpaceX satellite was estimated at one in 50,000. However, this increased to one in 1,000 when the US Air Force, which maintains perhaps the most comprehensive catalog of satellites, provided more detailed information.

Following LeoLabs’ warning, other organizations such as the Aerospace Corporation began to provide similarly worrying predictions. In contrast, calculations based on publicly available data were far more optimistic. Neither the US Air Force nor NASA issued any warning.

This was notable, as the United States had a role in the launch of both satellites involved in the near-miss. The first is the Infrared Astronomical Satellite (IRAS), a large space telescope weighing around a tonne and launched in 1983. It successfully completed its mission later that year and has floated dormant ever since.

The second satellite has a slightly more intriguing story. Known as GGSE-4, it is a formerly secret government satellite launched in 1967. It was part of a much larger project to capture radar emissions from the Soviet Union. This particular satellite also contained an experiment to explore ways to stabilize satellites using gravity.

Weighing in at 83kg, it is much smaller than IRAS, but it has a very unusual and unfortunate shape. It has an 18m protruding arm with a weight on the end, thus making it a much larger target.

Almost 24 hours later, LeoLabs tweeted again. It downgraded the chance of a collision to one in 1,000, and revised the predicted passing distance between the satellites to 13-87m. Although still closer than usual, this was a decidedly smaller risk. But less than 15 hours after that, the company tweeted yet again, raising the probability of collision back to one in 100, and then to a very alarming one in 20 after learning about the shape of GGSE-4.

The good news is that the two satellites appear to have missed one another. Although there were a handful of eyewitness accounts of the IRAS satellite appearing to pass unharmed through the predicted point of impact, it can still take a few hours for scientists to confirm that a collision did not take place. LeoLabs has since confirmed it has not detected any new space debris.

But why did the predictions change so dramatically and so often? What happened?

Tricky situation

The real problem is that we don’t really know precisely where these satellites are. That requires us to be extremely conservative, especially given the cost and importance of most active satellites, and the dramatic consequences of high-speed collisions.

The tracking of objects in space is often called Space Situational Awareness, and it is a very difficult task. One of the best methods is radar, which is expensive to build and operate. Visual observation with telescopes is much cheaper but comes with other complications, such as weather and lots of moving parts that can break down.

Another difficulty is that our models for predicting satellites’ orbits don’t work well in lower orbits, where drag from Earth’s atmosphere can become a factor.

There is yet another problem. Whereas it is in the best interest of commercial satellites for everyone to know exactly where they are, this is not the case for military and spy satellites. Defence organizations do not share the full list of objects they are tracking.

This potential collision involved an ancient spy from 1967. It is at least one that we can see. Given the difficulty of just tracking the satellites that we know about, how will we avoid satellites that are trying their hardest not to be seen?

In fact, much research has gone into building stealth satellites that are invisible from Earth. Even commercial industry is considering making satellites that are harder to see, partly in response to astronomers’ own concerns about objects blotting out their view of the heavens. SpaceX is considering building “dark satellites” the reflect less light into telescopes on Earth, which will only make them harder to track.

What should we do?

The solution starts with developing better ways to track satellites and space debris. Removing the junk is an important next step, but we can only do that if we know exactly where it is.

Western Sydney University is developing biology-inspired cameras that can see satellites during the day, allowing them to work when other telescopes cannot. These sensors can also see satellites when they move in front of bright objects like the Moon.

There is also no clear international space law or policy, but a strong need for one. Unfortunately, such laws will be impossible to enforce if we cannot do a better job of figuring out what is happening in orbit around our planet.


Explore further

Two defunct satellites narrowly miss collision: officials (Update)


Provided by
The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Citation:
Two satellites just avoided a head-on smash: How close did they come to disaster? (2020, January 30)
retrieved 30 January 2020
from https://phys.org/news/2020-01-satellites-head-on-disaster.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

What Are Fast Radio Bursts? – Worldatlas.com

Published

 on


The universe is full of mystery. No matter how much becomes known about the cosmos, there always seems to be more that is unknown. Any time a question is answered, more questions seem to arise, and so the process of scientific discovery becomes never ending. There are many examples of what is unknown about the cosmos, yet one perfect example is a phenomenon known as Fast Radio Bursts (FRB). As the name suggests, an FRB is a burst of radio waves that originate from the depths of interstellar space. They usually only last up to three seconds long, yet whatever releases them emits more energy in one second than our sun does every day. This suggests that FRBs are created by high energy processes, yet exactly what causes them remains unknown. 

Where Do FRBs Come From?

Most FRBs orignate in distant galaxies. Image credit: NASA/ESA

Most FRBs detected originate beyond the Milky Way Galaxy, yet some have been detected within our galaxy. To date, astronomers have detected around 500 FRBs, yet there remains no consensus on what actually creates them. That isn’t to say there aren’t any possible explanations, however. Some popular theories claim that FRBs originate from stellar remnants such as neutron stars or black holes. Other theories posit that they may originate from collisions between black holes or neutron stars. Another interesting theory is that FRBs come from a type of stellar remnant called a magnetar. A magnetar is a type of neutron star that has an exceptionally strong magnetic field and emits high amounts of x-rays and gamma rays, and some FRBs have been traced back to regions around magnetars. It’s quite possible that FRBs form from multiple different events, with no single phenomenon able to explain the origin of every FRB. 

Alien Origin

Galaxy Hubble
Hubble image of a distant galaxy. Image credit: NASA/ESA

Whenever astronomers detect signals of unknown origin, there is always the question of whether or not the signal originated from another civilization. Ever since humans began using technology to transmit signals around the world, some of the signals leak into space and travel at the speed of light. Any civilization that happens to be pointing a radio telescope in the right direction at the right time would detect our signals. Assuming other intelligent civilizations develop radio technology, they too would emit signals out into space that could be detected by us. Thus, some astronomers have wondered if some FRBs are in fact the radio signals from another civilization. Interestingly, this isn’t the first time this has happened. When astronomers discovered the first pulsars, they thought they had come across an alien signal, yet it later turned out to be a rapidly rotating neutron star. In the case of FRBs, it is unlikely they originate from another intelligent species. This is mainly due to the fact that they do not appear to come directly from other solar systems, and the bursts themselves contain so much energy that it seems unlikely a civilization would be creating them. Rather, a natural explanation is more likely, yet it still remains unknown exactly where FRBs come from.

Genius Dog 336 x 280 - Animated

Adblock test (Why?)



Source link

Continue Reading

Science

How Old Is The Sun? – Worldatlas.com

Published

 on


The sun formed around 4.6-billion years ago, and all the planets formed within the next 100-million years. The age of the sun and the planets is one of the most widely accepted facts about our solar system, and the reason for this is that every line of evidence points to the same age. How is the age of the sun determined?

Finding The Oldest Thing In The Solar System

One way to determine the approximate age of the sun is to find the oldest object in the solar system. Fortunately, there are countless objects that formed along with the sun, such as asteroids, meteors, and planetesimals. These forms of planetary debris remain virtually unchanged for billions of years, and by using radiometric dating methods, scientists can determine their age, in turn directly telling us how old the sun is. Radiometric dating uses precise chemicals to determine the age of rocks, and it works by using something called a half-life. For example, carbon-14 dating is a reliable method for dating things like fossils, as carbon-14 is only present in organic matter. Carbon-14 has a half-life of 5,730 years, meaning that after 5,730 years, half of the carbon-14 will decay into another chemical, in this case, nitrogen-14. Every 5,730 years, another half will decay and so on. By determining the amount of carbon-14 present relative to the amount of nitrogen-14, scientists can determine the age of whatever it is that is being analyzed. While carbon-14 is a reliable method for determining the age of organic matter, it will not work for determining things that are billions of years old. 

To find out when the sun first began to form, astronomers look for iron-60, a rare isotope of iron that is only produced during a supernova explosion. A supernova likely preceded the formation of our solar system, and the energy released from the explosion likely ignited the formation of the sun billions of years ago. Iron-60 has a half-life of 2.26-million years, wherein it decays into nickel-60. Like with carbon-14 and nitrogen-14, astronomers analyze rocks from asteroids and meteors to determine the ratio between iron-60 and nickel-60, which produces an age of around 4.6-billion years. Furthermore, other dating methods used on Earth and the moon have produced ages of around 4.5-billion years, offering further evidence that the sun is at least that old.

Genius Dog 336 x 280 - Animated

Lifespan Of The Sun

The Sun

The sun is 4.6-billion years old, and astronomers believe that it is only about halfway through its life. We obviously cannot see into the future, and so how do scientists estimate the amount of time the sun will exist for? The process is actually rather simple, and it involves knowing how much fuel the sun has and rate at which it consumes that fuel. Like every other star in the universe, the sun is powered by the nuclear fusion of hydrogen nuclei in its core. When hydrogen is fused together, it produces helium and vast amounts of energy that power the star. So long as nuclear fusion is maintained within the core, the sun will remain a main sequence star. However, that fuel will eventually run out, and when it does, the sun will enter into the final stages of life. By knowing the amount of fuel the sun has and the rate at which it uses that fuel, astronomers estimate that the sun will continue fusing hydrogen in its core for at least another 4 to 5-billion years. When the sun does begin to run out of usable hydrogen, it will evolve into a red giant, eventually blowing off its outer layers. Those outer layers will form a shell of stellar material called a planetary nebula. Meanwhile, the core of the sun will collapse and become a white dwarf. 

Adblock test (Why?)



Source link

Continue Reading

Science

UBC Okanagan study to investigate where Eurasian watermilfoil occurs in lakes

Published

 on

A UBC Okanagan pilot project is seeking to better pinpoint and map where the beginnings of Eurasian watermilfoil (EWM) infestation occurs in the large lakes within the Okanagan Valley watershed.

If this pilot project proves successful, it could become a blueprint for other jurisdictions to follow in their own battles with this aquatic plant or other invasive aquatic species, says UBCO assistant professor Mathieu Bourbonnais.

Bourbonnais, with the Irving K. Barber Faculty of Science, is overseeing the project with the assistance of masters graduate student Mackenzie Clarke.

The data modelling prototype is using the technology of topobathymetric lidar, the science of simultaneously measuring and recording three distinct surfaces – land, water and submerged land up to 20 metres below the water surface – using airborne laser-based infrared imagery sensors.

Genius Dog 336 x 280 - Animated

Bourbonnais says being able to better identify potential or small milfoil patches will give better control management tools for the Okanagan Basin Water Board’s Euroasian watermilfoil harvest program, which currently is about an $800,000 a year initiative to try and control the growth and limit the damage of the invasive water plant.

It could also potentially target specific watermilfoil growth sites before they grow out of control near valley lake areas deemed sensitive by Environment Canada for the preservation of the Rocky Mountain Ridge Mussels.

He said EWM has been a formidable invasive aquatic plant species to control since it was introduced into the Okanagan Valley lake system some 40 years ago.

It has also illustrated to the water board the need to be stringent when trying to avoid the Zebra and Quagga mussels from being introduced into the lake system.

Like watermilfoil, there is no solution for removing the mussels once they are introduced into a lake system. It is a rooted submerged plant inhabiting the shallows waters of lakes across North America.

EWM originated from Asia, Europe and Northern Africa and has spread rapidly, introduced in North America from the ballast water of ships or aquarium activities.

Bourbonnais said a lake choked with watermilfoil growth impacts the biodiversity and food webs reliant on the lake habitat, alter the water temperature and impacts its recreational use for swimmers and boaters.

“The impact of invasive species on our lake aquatic systems costs billions of dollars to deal with across the country. It definitely has an impact both ecologically and economically,” he said.

The pilot project fieldwork will be done by early spring, he said, with the hope it provides data upon which to target areas for harvesting leading up to the permit application process next year.

“The goal is the Okanagan Basin Water Board can take the data generated from this research model and liaise with the province and federal government on how to go forward,” he said.

“We hope it can help the management strategy of where to send the lake rototillers to pull up the plants.”

Source link

Continue Reading

Trending