[ad_1]
<div _ngcontent-c15 = "" innerhtml = "
Astronaut Story Musgrave on an EVA to the Space Telescope Hubble. The telescope has suffered from this problem, but current plans should keep this irreplaceable asset for astronomers operational for many years to come.NASA / STS-61
If you want to see the distant Universe with the highest sensitivities and smallest amounts of possible contamination, your best bet is to go to space. The Hubble Space Telescope, launched in April of 1990, is perhaps the most famous astronomical observatory in all of human history. Orbiting the Earth at an altitude of 550 kilometers (340 miles), at a speed of around 27,000 kph (17,000 mph), it completes to revolution around our planet every 95 minutes.
Simultaneously, the Earth spins on its axis and revolves around the Sun, which in turn moves around the galaxy at nearly 0.1% the speed of light. Yet, somehow, all of these motions. The key is in its guidance systems and, in particular, in its gyroscopes. Here's how, despite a recent failure, Hubble is poised to keep revealing the Universe's secrets for years to come.
This image shows Hubble servicing Mission 4 astronauts driving on a Hubble model underwater at the Neutral Buoyancy Lab in Houston under the watchful eyes of NASA engineers and safety divers. The 2009 mission was the final time the Hubble Space Telescope could be serviced.
Pointing at a single object without wavering or faltering is no small task. From its location in space, Hubble does not have to contend with the atmosphere, meaning that its resolution and imaging capabilities are limited only by the optics and instruments on board. Last upgraded in 2009, with the final Hubble servicing mission carried out from the Space Shuttle, Hubble is capable of delivering images with precision of just a few millionths of a degree.
But one of the key challenges is keeping your entire telescope steady and accurate in how it's pointed. To that end, the Hubble Space Telescope was designed to lock onto a target and hold its position steady to precisions of just 0.007 arcseconds. George Washington's eye, without fail, from a distance of 14 kilometers (8.7 miles) away.
The United States quarter dollar coin is the largest of the four major United States coins in circulation, but George Washington's eye is extremely tiny. If you could hit the eye with a laser pointer from a distance of 14 km, and maintain that position, you would achieve the accuracy of the Hubble Space Telescope. (Royalty-free photo / Getty Images)
Here on earth, we take it easy to get it all. We can not think of anything in the direction we want simply by manipulating it, by hand or by machine.
But the only reason we are able to do this is because of the earth. When you exert a force on any object, that object pushes against an opposite and equal force. That's because of the law, first discovered by Newton, stating that every action has an equal and opposite reaction.
A Soyuz-2.1a rocket lifts off on April 19, 2013, with Bion-M No. 1. Note the reaction of the exhaust for the action of accelerating the spacecraft, an example of Newton's third law.Roskosmos
But in space, there's nothing else to push against. However, you're moving, and that includes both your straight-line motion and your rotational motion, that's how you're going to continue to move. The only external forces come from gravitation and a very slight drag force of the atoms and particles that exist in interplanetary space.
If you were stuck facing the Sun and wanted to turn yourself in, you could not. If you're not spinning, you can not start spinning because there's nothing to push against. And similarly, if you're spinning, you could not slow yourself down, because there's also nothing to push against. Whether you're an object at rest or an object in motion, the only way that's going to change is if there's an external force.
In isolation, any system, whether at rest or in motion, including angular motion, will be unable to change that motion without an outside force. In space, your options are limited, but even in the International Space Station, one component (like an astronaut) can move against another (like another astronaut) to change the individual component's motion.NASA / International Space Station
This would work if you had a second object Astronauts aboard the International Space Station can move against the hull of the station or another astronaut, and change their momentum or angular momentum. The cost? Whatever you want to change its momentum or angular momentum by an equal-and-opposite amount.
So then, what do you do if you're a space telescope, up there on your own, without anything else to push against?
Hubble uses some very basic physics to turn itself around and look at different parts of the sky. Six gyroscopes (which, like a compass, always point in the same direction) and four free-spinning steering devices called reaction wheels are located on the telescope.NASA, ESA, A. Feild and K. Strings (STScI), and Lockheed Martin
You need a component of your motion. If you were alone in space, for example, by swiveling your lower body clockwise, you could then cause your upper body to swivel counterclockwise; you could push a different part of your body to change your orientation.
In a space telescope, we have different components of our bodies to work with, but we have different components of the telescope. And in the case of Hubble, we have an entire guidance system built on this principle.
The reaction wheels allow it to change its orientation, and the fine-guidance sensor allows it to determine how to orient itself. According to NASA itself:
To change angles, it uses Newton's third law by spinning its wheels in the opposite direction. It turns on the speed of a minute on a clock, taking 15 minutes to turn 90 degrees.
But keeping the stable telescope needs a key ingredient: gyroscopes.
A super-precise laser gyroscope was developed by the Russian scientific research and design association 'polyus,' as shown here in a 2002 photo. The gyroscopes on Hubble are even more advanced, and are in many ways the most accurate in human history. (Sovfoto / UIG via Getty Images)
Without those gyroscopes, tiny external forces would cause Hubble's orientation to drift over time, and would make long-exposure images impossible. But with them, we can keep the telescope stable.
In 2009, during the final servicing mission, all six of Hubble's gyroscopes were replaced, in the hopes of extending its life as long as possible. The gyroscopes maintain orientation and provide stability by pushing back against any force that attempts to change its orientation. For Hubble, each gyroscope contains a wheel that spins at 19,200 rpms, and is required for optimal operating efficiency. The reason we need three is simple: there are three dimensions in space, and so three independent ways that a spacecraft could potentially change its orientation. With three gyroscopes operating at once, we can achieve maximum stability.
The Hubble Space Telescope, as imaged during its last and final servicing mission. The only way it can point itself is to allow it to change its orientation and hold a stable position.NASA
On October 5th, 2018, the Hubble Space Telescope entered safe mode, one of the three gyroscopes actively being used to point-and-steady the telescope had failed. Engineers have fixed problems of this kind, from the ground, by firing up another of the on-board gyroscopes and switching which are used to stabilize the observatory. The gyroscope that failed was not completely surprising; it had been showing signs of trouble for a year.
But there are already two other gyroscopes which had failed in the past six months. With two good gyroscopes and one partially-malfunctioning one, it's a solemn reminder that Hubble will not live forever.
We are exploring more and more of the Universe, we are able to look farther away in space, which equates to farther back in time. The James Webb Space Telescope will take us to the depths of our lives, and we will be able to take a closer look at this.NASA / JWST and HST teams
With two fully functioning gyroscopes, the team operating Hubble will switch to the final plan: operating in one-gyroscope mode. With three gyroscopes, you can keep your observatory steady; with less than that, your perspective on the sky suddenly becomes restricted.
That's why the plan is to attempt to fix the partially-malfunctioning remotely gyroscope. If you succeed, you have three functioning gyroscopes and Hubble can continue to operate as normal. If they can not cure the partially-malfunctioning gyroscope, they will power-down one of the functional gyroscopes and save it. You can see how much you can do with two gyroes, but you can still find your own telescope by using one gyroscope at a time instead of two together. At a cost of reduced sky coverage and slower pointing times, you can extend Hubble's life.
This photo of the Hubble Space telescope being deployed, on April 25. 1990, was taken by the IMAX Cargo Bay Camera (ICBC) mounted aboard the space shuttle Discovery. It has been operational for more than 28 years, but has not been serviced since 2009.NASA / Smithsonian Institution / Lockheed Corporation
It might seem to be just another example of crumbling infrastructure in the United States, but you must not be underestimate Hubble nor the resourcefulness of astronomers and scientists and engineers overall. The two (or maybe three) remaining gyroscopes are a new and upgraded design, designed to last as long as the original gyroscopes, which includes the one that recently failed. The James Webb Space Telescope, despite being billed as Hubble's successor, is actually quite different, and will launch in 2021.
Even with one gyroscope, the Hubble Space Telescope should still be operational and capable of providing additional observations to James Webb. This reduced-gyro mode has been planned for a long time. The only disappointment is that we can enter it soon.
">
Astronaut Story Musgrave on an EVA to the Space Telescope Hubble. The telescope has suffered from this problem, but current plans should keep this irreplaceable asset for astronomers operational for many years to come.NASA / STS-61
If you want to see the distant Universe with the highest sensitivities and smallest amounts of possible contamination, your best bet is to go to space. The Hubble Space Telescope, launched in April of 1990, is perhaps the most famous astronomical observatory in all of human history. Orbiting the Earth at an altitude of 550 kilometers (340 miles), at a speed of around 27,000 kph (17,000 mph), it completes to revolution around our planet every 95 minutes.
Simultaneously, the Earth spins on its axis and revolves around the Sun, which in turn moves around the galaxy at nearly 0.1% the speed of light. Yet, somehow, all of these motions. The key is in its guidance systems and, in particular, in its gyroscopes. Here's how, despite a recent failure, Hubble is poised to keep revealing the Universe's secrets for years to come.
This image shows Hubble servicing Mission 4 astronauts driving on a Hubble model underwater at the Neutral Buoyancy Lab in Houston under the watchful eyes of NASA engineers and safety divers. The 2009 mission was the final time the Hubble Space Telescope could be serviced.
Pointing at a single object without wavering or faltering is no small task. From its location in space, Hubble does not have to contend with the atmosphere, meaning that its resolution and imaging capabilities are limited only by the optics and instruments on board. Last upgraded in 2009, with the final Hubble servicing mission carried out from the Space Shuttle, Hubble is capable of delivering images with precision of just a few millionths of a degree.
But one of the key challenges is keeping your entire telescope steady and accurate in how it's pointed. To that end, the Hubble Space Telescope was designed to lock onto a target and hold its position steady to precisions of just 0.007 arcseconds. George Washington's eye, without fail, from a distance of 14 kilometers (8.7 miles) away.
The United States quarter dollar coin is the largest of the four major United States coins in circulation, but George Washington's eye is extremely tiny. If you could hit the eye with a laser pointer from a distance of 14 km, and maintain that position, you would achieve the accuracy of the Hubble Space Telescope. (Royalty-free photo / Getty Images)
Here on earth, we take it easy to get it all. We can not think of anything in the direction we want simply by manipulating it, by hand or by machine.
But the only reason we are able to do this is because of the earth. When you exert a force on any object, that object pushes against an opposite and equal force. That's because of the law, first discovered by Newton, stating that every action has an equal and opposite reaction.
A Soyuz-2.1a rocket lifts off on April 19, 2013, with Bion-M No. 1. Note the reaction of the exhaust for the action of accelerating the spacecraft, an example of Newton's third law.Roskosmos
But in space, there's nothing else to push against. However, you're moving, and that includes both your straight-line motion and your rotational motion, that's how you're going to continue to move. The only external forces come from gravitation and a very slight drag force of the atoms and particles that exist in interplanetary space.
If you were stuck facing the Sun and wanted to turn yourself in, you could not. If you're not spinning, you can not start spinning because there's nothing to push against. And similarly, if you're spinning, you could not slow yourself down, because there's also nothing to push against. Whether you're an object at rest or an object in motion, the only way that's going to change is if there's an external force.
In isolation, any system, whether at rest or in motion, including angular motion, will be unable to change that motion without an outside force. In space, your options are limited, but even in the International Space Station, one component (like an astronaut) can move against another (like another astronaut) to change the individual component's motion.NASA / International Space Station
This would work if you had a second object Astronauts aboard the International Space Station can move against the hull of the station or another astronaut, and change their momentum or angular momentum. The cost? Whatever you want to change its momentum or angular momentum by an equal-and-opposite amount.
So then, what do you do if you're a space telescope, up there on your own, without anything else to push against?
Hubble uses some very basic physics to turn itself around and look at different parts of the sky. Six gyroscopes (which, like a compass, always point in the same direction) and four free-spinning steering devices called reaction wheels are located on the telescope.NASA, ESA, A. Feild and K. Strings (STScI), and Lockheed Martin
You need a component of your motion. If you were alone in space, for example, by swiveling your lower body clockwise, you could then cause your upper body to swivel counterclockwise; you could push a different part of your body to change your orientation.
In a space telescope, we have different components of our bodies to work with, but we have different components of the telescope. And in the case of Hubble, we have an entire guidance system built on this principle.
The reaction wheels allow it to change its orientation, and the fine-guidance sensor allows it to determine how to orient itself. According to NASA itself:
To change angles, it uses Newton's third law by spinning its wheels in the opposite direction. It turns on the speed of a minute on a clock, taking 15 minutes to turn 90 degrees.
But keeping the stable telescope needs a key ingredient: gyroscopes.
A super-precise laser gyroscope was developed by the Russian scientific research and design association 'polyus,' as shown here in a 2002 photo. The gyroscopes on Hubble are even more advanced, and are in many ways the most accurate in human history. (Sovfoto / UIG via Getty Images)
Without those gyroscopes, tiny external forces would cause Hubble's orientation to drift over time, and would make long-exposure images impossible. But with them, we can keep the telescope stable.
In 2009, during the final servicing mission, all six of Hubble's gyroscopes were replaced, in the hopes of extending its life as long as possible. The gyroscopes maintain orientation and provide stability by pushing back against any force that attempts to change its orientation. For Hubble, each gyroscope contains a wheel that spins at 19,200 rpms, and is required for optimal operating efficiency. The reason we need three is simple: there are three dimensions in space, and so three independent ways that a spacecraft could potentially change its orientation. With three gyroscopes operating at once, we can achieve maximum stability.
The Hubble Space Telescope, as imaged during its last and final servicing mission. The only way it can point itself is to allow it to change its orientation and hold a stable position.NASA
On October 5th, 2018, the Hubble Space Telescope entered safe mode, one of the three gyroscopes actively being used to point-and-steady the telescope had failed. Engineers have fixed problems of this kind, from the ground, by firing up another of the on-board gyroscopes and switching which are used to stabilize the observatory. The gyroscope that failed was not completely surprising; it had been showing signs of trouble for a year.
But there are already two other gyroscopes which had failed in the past six months. With two good gyroscopes and one partially-malfunctioning one, it's a solemn reminder that Hubble will not live forever.
We are exploring more and more of the Universe, we are able to look farther away in space, which equates to farther back in time. The James Webb Space Telescope will take us to the depths of our lives, and we will be able to take a closer look at this.NASA / JWST and HST teams
With two fully functioning gyroscopes, the team operating Hubble will switch to the final plan: operating in one-gyroscope mode. With three gyroscopes, you can keep your observatory steady; with less than that, your perspective on the sky suddenly becomes restricted.
That's why the plan is to attempt to fix the partially-malfunctioning remotely gyroscope. If you succeed, you have three functioning gyroscopes and Hubble can continue to operate as normal. If they can not cure the partially-malfunctioning gyroscope, they will power-down one of the functional gyroscopes and save it. You can see how much you can do with two gyroes, but you can still find your own telescope by using one gyroscope at a time instead of two together. At a cost of reduced sky coverage and slower pointing times, you can extend Hubble's life.
This photo of the Hubble Space telescope being deployed, on April 25. 1990, was taken by the IMAX Cargo Bay Camera (ICBC) mounted aboard the space shuttle Discovery. It has been operational for more than 28 years, but has not been serviced since 2009.NASA / Smithsonian Institution / Lockheed Corporation
It might seem to be just another example of crumbling infrastructure in the United States, but you must not be underestimate Hubble nor the resourcefulness of astronomers and scientists and engineers overall. The two (or maybe three) remaining gyroscopes are a new and upgraded design, designed to last as long as the original gyroscopes, which includes the one that recently failed. The James Webb Space Telescope, despite being billed as Hubble's successor, is actually quite different, and will launch in 2021.
Even with one gyroscope, the Hubble Space Telescope should still be operational and capable of providing additional observations to James Webb. This reduced-gyro mode has been planned for a long time. The only disappointment is that we can enter it soon.
