Hubble Orbit
Although the Hubble Space Telescope has been in orbit since 1990, its origins date long before that. The first serious concepts of a space-based optical observatory began just after World War II. 6 hours ago #ThrowBackToday: The gorgeous pictures Hubble telescope relays back since it was launched into Earth's orbit three decades ago In today's #TBT, we tell you about the Hubble Space Telescope and why its Instagram account is the one you should ardently follow. Also, Suez Canal's construction began today! Here's all about it. Indicates the amount, in kilometers, existing between the observer and the satellite. Period is the time that the satellite takes to complete an orbit around the Earth, counted from perigee to perigee. Azimuth and Elevation are the local coordinates and they inform the position on the sky where the observer should look to see the satellite or to point out his antenna. Altitude is the. NASA’s Hubble Space Telescope (HST) was launched into orbit on the space shuttle Discovery on April 24, 1990. Thanks to its perch above most of Earth’s turbulent atmosphere, the telescope’s relatively modest 2.4-meter mirror has given us an unprecedented window on the universe for nearly 30 years. But just how much longer will Hubble last?
© Provided by Mashable On Hubble's 31st birthday, NASA points at a stunning 'celebrity star'Smile, Hubble! You turn 31 today.
The Hubble Space Telescope launched into orbit on April 24, 1990, and it's been looking into the far reaches of space and beaming images back to us ever since. In honor of its 31st birthday, NASA turned the space telescope's attention toward a distant and jaw-droppingly beautiful 'celebrity star.'
Hubble Orbit Height
AG Carinae, which NASA calls one of the brightest stars seen in our galaxy, we can thank space gas and space dust for this beautiful explosion of light and color. The star exploded outwards around 10,000 years ago, releasing all the stellar material making up its gorgeous halo in the process.
This sort of explosion is typical for the type of star AG Carinae is — a luminous blue variable. 'These outbursts are the typical life of a rare breed of star called a luminous blue variable, a brief convulsive phase in the short life of an ultra-bright glamorous star that lives fast and dies young.' That description should eliminate any confusion as to where the 'celebrity star' moniker comes in.
The lifetime of such stars can be measured in the millions of years — for comparison, our middle-aged sun is now about 4.5 billion years old. They're pretty chill for a portion of their lives, before erupting and turning into the kind of celestial body you see above. It's hard to understand scale from the one image, but that blast covers a lot of territory.
The halo has a diameter of about five light-years, which is about how far our own sun is from the nearest neighboring star, Proxima Centauri. The stellar material making up that halo is also equal to roughly 10 times the material making up our sun.
Hubble senior project scientist Jennifer Wiseman narrated a brief video on AG Carinae and Hubble's life so far, released on the April 24 anniversary of its launch.
NASA also released some eye-catching statistics on the space telescope's work to this point. In total, the Hubble Space Telescope has made more than 1.5 million 'observations' (it's not just snapshots!) of roughly 48,000 celestial objects. That amounts to about 169 terabytes of data, with much of it catalogued at HubbleSite.org.
It's been a long run for Hubble, but one of its long-in-development successors will soon arrive in orbit. The James Webb Space Telescope was at one point expected to launch as far back as 2007. That never happened obviously, and numerous delays in recent years — both before and because of the COVID pandemic — have kept it grounded. But it's currently targeting a launch of Oct. 31, 2021.
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The Webb telescope represents a big upgrade over Hubble. NASA has staged multiple missions to service the aging telescope, but it'll eventually be rendered obsolete by stellar mechanics if nothing else. This CBS News report from 2013 notes that we can expect Hubble's degrading orbit to send it falling back to Earth sometime in the range of 2030 to 2040.
Overview
Webb often gets called the replacement for Hubble, but we prefer to call it a successor. After all, Webb is the scientific successor to Hubble; its science goals were motivated by results from Hubble. Hubble's science pushed us to look to longer wavelengths to 'go beyond' what Hubble has already done. In particular, more distant objects are more highly redshifted, and their light is pushed from the UV and optical into the near-infrared. Thus observations of these distant objects (like the first galaxies formed in the Universe, for example) requires an infrared telescope.
This is the other reason that Webb is not a replacement for Hubble; its capabilities are not identical. Webb will primarily look at the Universe in the infrared, while Hubble studies it primarily at optical and ultraviolet wavelengths (though it has some infrared capability). Webb also has a much bigger mirror than Hubble. This larger light collecting area means that Webb can peer farther back into time than Hubble is capable of doing. Hubble is in a very close orbit around the earth, while Webb will be 1.5 million kilometers (km) away at the second Lagrange (L2) point.
More Detail
Hubble Orbit Height
Read on to explore some of the details of what these differences mean.
Wavelength
Webb will observe primarily in the infrared and will have four science instruments to capture images and spectra of astronomical objects. These instruments will provide wavelength coverage from 0.6 to 28 micrometers (or 'microns'; 1 micron is 1.0 x 10-6 meters). The infrared part of the electromagnetic spectrum goes from about 0.75 microns to a few hundred microns. This means that Webb's instruments will work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range (in particular in the red and up to the yellow part of the visible spectrum).
The instruments on Hubble can observe a small portion of the infrared spectrum from 0.8 to 2.5 microns, but its primary capabilities are in the ultra-violet and visible parts of the spectrum from 0.1 to 0.8 microns.
Why are infrared observations important to astronomy? Stars and planets that are just forming lie hidden behind cocoons of dust that absorb visible light. (The same is true for the very center of our galaxy.) However, infrared light emitted by these regions can penetrate this dusty shroud and reveal what is inside.
At left are infrared and visible light images from the Hubble Space Telescope of the Monkey Head Nebula, a star-forming region. A jet of material from a newly forming star is visible in one of the pillars, just above and left of centre in the right-hand image. Several galaxies are seen in the infrared view, much more distant than the columns of dust and gas.
Size Comparisons
Orbit
The Earth is 150 million km from the Sun and the moon orbits the earth at a distance of approximately 384,500 km. The Hubble Space Telescope orbits around the Earth at an altitude of ~570 km above it. Webb will not actually orbit the Earth - instead it will sit at the Earth-Sun L2 Lagrange point, 1.5 million km away!
Because Hubble is in Earth orbit, it was able to be launched into space by the space shuttle. Webb will be launched on an Ariane 5 rocket and because it won't be in Earth orbit, it is not designed to be serviced by the space shuttle.
At the L2 point Webb's solar shield will block the light from the Sun, Earth, and Moon. This will help Webb stay cool, which is very important for an infrared telescope.
As the Earth orbits the Sun, Webb will orbit with it - but stay fixed in the same spot with relation to the Earth and the Sun, as shown in the diagram to the left. Actually, satellites orbit around the L2 point, as you can see in the diagram - they don't stay completely motionless at a fixed spot.
How Far Will Webb see?
Hubble Orbit Time
Because of the time it takes light to travel, the farther away an object is, the farther back in time we are looking.
This illustration compares various telescopes and how far back they are able to see. Essentially, Hubble can see the equivalent of 'toddler galaxies' and Webb Telescope will be able to see 'baby galaxies'. One reason Webb will be able to see the first galaxies is because it is an infrared telescope. The universe (and thus the galaxies in it) is expanding. When we talk about the most distant objects, Einstein's General Relativity actually comes into play. It tells us that the expansion of the universe means it is the space between objects that actually stretches, causing objects (galaxies) to move away from each other. Furthermore, any light in that space will also stretch, shifting that light's wavelength to longer wavelengths. This can make distant objects very dim (or invisible) at visible wavelengths of light, because that light reaches us as infrared light. Infrared telescopes, like Webb, are ideal for observing these early galaxies.
What About Herschel?
The Herschel Space Observatory was an infrared telescope built by the European Space Agency - it too orbited the L2 point (where Webb will be).
The primary difference between Webb and Herschel is wavelength range: Webb goes from 0.6 to 28.5 microns; Herschel went from 60 to 500 microns. Webb is also larger, with an approximately 6.5 meter mirror vs. Herschel's 3.5 meters.
Hubble Orbit Tracking
The wavelength ranges were chosen by different science: Herschel looked for the extremes, the most actively star-forming galaxies, which emit most of their energy in the far-IR. Webb will find the first galaxies to form in the early universe, for which it needs extreme sensitivity in the near-IR.
Hubble Orbit Path
At right is an infrared image of the Andromeda Galaxy (M31) taken by Herschel (orange) with an X-ray image from XMM-Newton superposed over it (blue).