James Webb Space Telescope

 

 James Webb space telescope

This ambitious telescope is intended to replace the Hubble telescope which has worked well after it’s initial problems. The James Webb space telescope ( JWST ) is a rather different and much more complex telescope, It works mainly in the infra-red  ( IR ) region of light. Humans cannot see in this region although it can be felt as warming if it is absorbed. The electromagnetic spectrum consists of far more than the light we can see down through X rays and up ( in wavelength ) through radio waves.

The infra red region was chosen for the reason it is very difficult for earth bound telescopes to observe because of absorption in the atmosphere. Areas of dust which are opaque in visible light can be transparent in the infra red. A very important reason is that light from very distant objects are usually travelling away at very high speeds. Light emitted by them has its visible light “stretched” by the Doppler effect so that it falls into the infra red region. The Doppler effect is the change in frequency of radiation experienced by an observer of an object travelling towards or away. The common experience is the change in pitch of sound experienced on a platform as a train passes by. High at first as the waves are “compressed” as the train approaches then falling to a lower pitch as the train passes away.

Because light travels at a finite speed as objects are further away their light takes longer to reach us. Light from the nearest star takes about 4 years to reach earth .As we look deeper into the universe so we are looking back in time. It is thought that the JWST will enable the very early universe to be observed because it will look at objects so far distant. It is speculated that the JWST will enable the formation of stars after the big bang to be seen. The very early universe will probably be opaque but the JWST may reach back as far as it is possible to go.

Because it is mainly an IR telescope it has a slightly strange shape. Essentially the telescope sits on top of a large sunshade. This ensures that the side in shadow ( the telescope side ) is  cold. Very cold indeed which is needed for IR viewing. The very large telescope of some 6.5 metre diameter ( compares to Hubble about 2.5metre ) is made up of 18 hexagonal segments all of whom need to be very precisely aligned with each other so that effectively they become one whole. These mirror segments reflect onto one target held in front of the mirror The mirror segments are of gold deposited on a beryllium substrate.

The JWST is positioned in space orbiting the spot where the sun and earth’s gravity just balance out. This is known as the L2 Lagrange point. It should enable the telescope to remain in nearly one position while expending the minimum amount of energy.

The JWST is very expensive. It will have cost an estimated $10bn by the time it becomes fully operational which is expected in May. It was launched last year and has spent until now reaching its final position and aligning its mirrors.  Because the whole had to be packed into a rocket nosecone much had be folded up and then unfurled in space. Because of this elaborate design and overall complexity the cost has risen from the original budget of $0.5bn. Such a cost had to be shared between NASA, ESA and the Canadian Space Agency ( presumably the UK was then part of ESA ) An estimated 250 companies were involved in the project ( 21 from the UK ) and several thousands of scientists and engineers. Launch of such a complex and expensive payload was by ESA Ariane rocket from French Guiana. One imagines that there was a lot of anxiety during the launch and subsequent deployment. While it is still too early to state that everything is as designed all the evidence so far is that things are going to plan.

The early months of the JWST operation already have science programs planned. Subsequent operations during the planned 10 year life remain somewhat flexible but certainly include observation of exoplanets as well as a variety of astrophysics .Some of the early experiments will assess the usefulness of JWST for things like study of the solar system after a specific study of Jupiter. However at this stage much is unknown and part of the hope is that JWST discover new things. At present astrophysics is confounded by the knowledge that dark matter and dark energy make up a large portion of the universe ( 90% + )  but other than giving them a name no more is known.

The massive cost over-run of JWST bodes ill for big science projects. The difficulty is that the study of complex physics tends to require large and expensive equipment. Examples are the gravitational wave detection ( LIGO ) and the large hadron collider at CERN. To some extent the gigantic costs are offset by international co-operation. With the Russian invasion of Ukraine it looks as through Russian participation is doubtful. They are already withdrawing from the international space station. Although these large international projects are very expensive they are also very productive with entirely new areas explored and involving many hundreds of scientists.

Perhaps the most expensive and complex international endeavour under construction at present is ITER which attempts to be a major step towards making fusion energy practical.James Webb space telescope

This ambitious telescope is intended to replace the Hubble telescope which has worked well after it’s initial problems. The James Webb space telescope ( JWST ) is a rather different and much more complex telescope, It works mainly in the infra-red  ( IR ) region of light. Humans cannot see in this region although it can be felt as warming if it is absorbed. The electromagnetic spectrum consists of far more than the light we can see down through X rays and up ( in wavelength ) through radio waves.

The infra red region was chosen for the reason it is very difficult for earth bound telescopes to observe because of absorption in the atmosphere. Areas of dust which are opaque in visible light can be transparent in the infra red. A very important reason is that light from very distant objects are usually travelling away at very high speeds. Light emitted by them has its visible light “stretched” by the Doppler effect so that it falls into the infra red region. The Doppler effect is the change in frequency of radiation experienced by an observer of an object travelling towards or away. The common experience is the change in pitch of sound experienced on a platform as a train passes by. High at first as the waves are “compressed” as the train approaches then falling to a lower pitch as the train passes away.

Because light travels at a finite speed as objects are further away their light takes longer to reach us. Light from the nearest star takes about 4 years to reach earth .As we look deeper into the universe so we are looking back in time. It is thought that the JWST will enable the very early universe to be observed because it will look at objects so far distant. It is speculated that the JWST will enable the formation of stars after the big bang to be seen. The very early universe will probably be opaque but the JWST may reach back as far as it is possible to go.

Because it is mainly an IR telescope it has a slightly strange shape. Essentially the telescope sits on top of a large sunshade. This ensures that the side in shadow ( the telescope side ) is  cold. Very cold indeed which is needed for IR viewing. The very large telescope of some 6.5 metre diameter ( compares to Hubble about 2.5metre ) is made up of 18 hexagonal segments all of whom need to be very precisely aligned with each other so that effectively they become one whole. These mirror segments reflect onto one target held in front of the mirror The mirror segments are of gold deposited on a beryllium substrate.

The JWST is positioned in space orbiting the spot where the sun and earth’s gravity just balance out. This is known as the L2 Lagrange point. It should enable the telescope to remain in nearly one position while expending the minimum amount of energy.

The JWST is very expensive. It will have cost an estimated $10bn by the time it becomes fully operational which is expected in May. It was launched last year and has spent until now reaching its final position and aligning its mirrors.  Because the whole had to be packed into a rocket nosecone much had be folded up and then unfurled in space. Because of this elaborate design and overall complexity the cost has risen from the original budget of $0.5bn. Such a cost had to be shared between NASA, ESA and the Canadian Space Agency ( presumably the UK was then part of ESA ) An estimated 250 companies were involved in the project ( 21 from the UK ) and several thousands of scientists and engineers. Launch of such a complex and expensive payload was by ESA Ariane rocket from French Guiana. One imagines that there was a lot of anxiety during the launch and subsequent deployment. While it is still too early to state that everything is as designed all the evidence so far is that things are going to plan.

The early months of the JWST operation already have science programs planned. Subsequent operations during the planned 10 year life remain somewhat flexible but certainly include observation of exoplanets as well as a variety of astrophysics .Some of the early experiments will assess the usefulness of JWST for things like study of the solar system after a specific study of Jupiter. However at this stage much is unknown and part of the hope is that JWST discover new things. At present astrophysics is confounded by the knowledge that dark matter and dark energy make up a large portion of the universe ( 90% + )  but other than giving them a name no more is known.

The massive cost over-run of JWST bodes ill for big science projects. The difficulty is that the study of complex physics tends to require large and expensive equipment. Examples are the gravitational wave detection ( LIGO ) and the large hadron collider at CERN. To some extent the gigantic costs are offset by international co-operation. With the Russian invasion of Ukraine it looks as through Russian participation is doubtful. They are already withdrawing from the international space station. Although these large international projects are very expensive they are also very productive with entirely new areas explored and involving many hundreds of scientists.

Perhaps the most expensive and complex international endeavour under construction at present is ITER which attempts to be a major step towards making fusion energy practical.

This ambitious telescope is intended to replace the Hubble telescope which has worked well after it’s initial problems. The James Webb space telescope ( JWST ) is a rather different and much more complex telescope, It works mainly in the infra-red  ( IR ) region of light. Humans cannot see in this region although it can be felt as warming if it is absorbed. The electromagnetic spectrum consists of far more than the light we can see down through X rays and up ( in wavelength ) through radio waves.

The infra red region was chosen for the reason it is very difficult for earth bound telescopes to observe because of absorption in the atmosphere. Areas of dust which are opaque in visible light can be transparent in the infra red. A very important reason is that light from very distant objects are usually travelling away at very high speeds. Light emitted by them has its visible light “stretched” by the Doppler effect so that it falls into the infra red region. The Doppler effect is the change in frequency of radiation experienced by an observer of an object travelling towards or away. The common experience is the change in pitch of sound experienced on a platform as a train passes by. High at first as the waves are “compressed” as the train approaches then falling to a lower pitch as the train passes away.

Because light travels at a finite speed as objects are further away their light takes longer to reach us. Light from the nearest star takes about 4 years to reach earth .As we look deeper into the universe so we are looking back in time. It is thought that the JWST will enable the very early universe to be observed because it will look at objects so far distant. It is speculated that the JWST will enable the formation of stars after the big bang to be seen. The very early universe will probably be opaque but the JWST may reach back as far as it is possible to go.

Because it is mainly an IR telescope it has a slightly strange shape. Essentially the telescope sits on top of a large sunshade. This ensures that the side in shadow ( the telescope side ) is  cold. Very cold indeed which is needed for IR viewing. The very large telescope of some 6.5 metre diameter ( compares to Hubble about 2.5metre ) is made up of 18 hexagonal segments all of whom need to be very precisely aligned with each other so that effectively they become one whole. These mirror segments reflect onto one target held in front of the mirror The mirror segments are of gold deposited on a beryllium substrate.

The JWST is positioned in space orbiting the spot where the sun and earth’s gravity just balance out. This is known as the L2 Lagrange point. It should enable the telescope to remain in nearly one position while expending the minimum amount of energy.

The JWST is very expensive. It will have cost an estimated $10bn by the time it becomes fully operational which is expected in May. It was launched last year and has spent until now reaching its final position and aligning its mirrors.  Because the whole had to be packed into a rocket nosecone much had be folded up and then unfurled in space. Because of this elaborate design and overall complexity the cost has risen from the original budget of $0.5bn. Such a cost had to be shared between NASA, ESA and the Canadian Space Agency ( presumably the UK was then part of ESA ) An estimated 250 companies were involved in the project ( 21 from the UK ) and several thousands of scientists and engineers. Launch of such a complex and expensive payload was by ESA Ariane rocket from French Guiana. One imagines that there was a lot of anxiety during the launch and subsequent deployment. While it is still too early to state that everything is as designed all the evidence so far is that things are going to plan.

The early months of the JWST operation already have science programs planned. Subsequent operations during the planned 10 year life remain somewhat flexible but certainly include observation of exoplanets as well as a variety of astrophysics .Some of the early experiments will assess the usefulness of JWST for things like study of the solar system after a specific study of Jupiter. However at this stage much is unknown and part of the hope is that JWST discover new things. At present astrophysics is confounded by the knowledge that dark matter and dark energy make up a large portion of the universe ( 90% + )  but other than giving them a name no more is known.

The massive cost over-run of JWST bodes ill for big science projects. The difficulty is that the study of complex physics tends to require large and expensive equipment. Examples are the gravitational wave detection ( LIGO ) and the large hadron collider at CERN. To some extent the gigantic costs are offset by international co-operation. With the Russian invasion of Ukraine it looks as through Russian participation is doubtful. They are already withdrawing from the international space station. Although these large international projects are very expensive they are also very productive with entirely new areas explored and involving many hundreds of scientists.

Perhaps the most expensive and complex international endeavour under construction at present is ITER which attempts to be a major step towards making fusion energy practical.