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Airborne observatory

From Wikipedia, the free encyclopedia

NASA's airborne infrared observatories — the Learjet Observatory, the Kuiper Airborne Observatory and SOFIA — pictured next to illustrations showing how the size of each telescope approximately compares to an adult.

An airborne observatory is an airplane or airship with an astronomical telescope. By carrying the telescope to a sufficiently high altitude, the telescope can avoid cloud cover, pollution, and carry out observations in the infrared spectrum, above water vapor in the atmosphere which absorbs infrared radiation. Some drawbacks to this approach are the instability of the lifting platform, the weight restrictions on the instrument, the need to safely recover the gear afterward, and the cost compared to a comparable ground-based observatory.

Multiple observations of solar eclipses were performed from 1920 to 1980. NASA created first specialised airborne observatory, Galileo, in 1965. SOFIA, the latest such observatory, was retired in 2022.

YouTube Encyclopedic

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  • Inside NASA's SOFIA Airborne Astronomical Observatory
  • Airborne Astronomy Ambassadors Begin Flights on SOFIA Observatory
  • German Airborne Astronomy Ambassadors fly aboard SOFIA Observatory
  • Kuiper Airborne Observatory
  • Stratospheric Observatory for Infrared Astronomy

Transcription

[ Music ] >> Pamela Marcum: I think of SOFIA mostly as sort of catching light. >> Brent Cobleigh: Day after day we can get up and do these missions and really do really cutting edge astronomy in the infrared spectrum. [ Music ] SOFIA is an observatory. And like other observatories around the world, it can do a lot of different science. A lot of those observatories are on the tops of mountains around 13,000 or 14,000 feet. >> Michael Person: Even when we have a ground-based telescope in a perfect place, sometimes it doesn't get any data because the clouds come in. Being able to fly over all of that is just a tremendous asset. >> Pamela Marcum: What happens is in the upper atmosphere of the Earth, as the light comes down, you know, from some astronomical object, very little of that light is able to pass all the way down to the ground. So what SOFIA does is it flies above the bulk of that water in the atmosphere. [ Music ] >> Brent Cobleigh: SOFIA can fly at 43,000 feet, more than double the height of all of the other observatories in the world. >> Eddie Zavala: And that is above 90% of the water vapor. And that's a position that is necessary for astronomers to do infrared astronomy. [ Music ] >> Brent Cobleigh: The space-based observatories have some really unique aspects to them. They're always in space. They're very cold. They can observe round the clock day in and day out. >> Alois Himmes: The spacecraft demand on low weight, low power consumption are very extreme so in an airborne observatory you have a lot of power, a lot of space available. [ Music ] >> Brent Cobleigh: We can carry instruments that are hundreds of pounds. We can give those instruments much more power than you can generate from solar collectors in space. We're not limited to the minimum weight that launch vehicles require to put something in to space. We can fix those instruments day after day. The airplane comes home. We can repair them. It's very, very challenging to ever repair anything in space. And it has been done very, very few times. [ Background Discussion ] >> Pamela Marcum: The plane provides this motion as the telescope provides this motion. And together you're actually able to track a target as it moves across the sky as it's rising and setting. Not only does it have to be aware of time and position, but it's also got to be making the right motions across the surfaces of the Earth so that combined motions allow us to be able to lock on to the object over periods of a couple of hours. One of the powerful benefits that SOFIA brings us is the ability to go chasing these occultations in a way that no other observatory can do. [ Music ] >> Eddie Zavala: An occultation is basically a situation where a planet or an object of interest moves in front of a background star. >> Pamela Marcum: We observed a Pluto occultation, so that was where Pluto fell in our line of sight with the background star and made that star's light blink out very momentarily. >> Eddie Zavala: They modeled where that shadow is going to be, and we flew this airplane at roughly 500 miles an hour to catch a shadow that was going across the surface of the Earth at 53,000 miles an hour. >> Pamela Marcum: Simply by looking at the way that the background light blinked out, tells us something about the shape of the object, whether that object has an atmosphere or not, and even determine things like how the atmosphere's temperature and pressure vary from the ground all the way up to the top of that atmosphere on that object. [ Music ] You are limited as to what parts of the sky you can actually observe when you're in the Northern Hemisphere. So deployments out of our home base here in Palmdale gives us access to one half of the sphere. And when we go down to New Zealand, we'll have access to a whole new set of objects, a whole new part of the sky. [ Music ] Infrared astronomy allows you to peer into the core of really cold gas clouds where the stars are starting to form, planets, comets, dust particles...to look at star formation in extreme regions. These things, because of their cold temperatures, happen to radiate most of their energy at these infrared wavelengths that SOFIA studies. [ Music ] SOFIA actually has several different instruments. >> Brent Cobleigh: The science instruments receive the electromagnetic spectrum, the light, through the telescope. >> Alois Himmes: Instruments mean cameras or photometers or spectrometers. The telescope without instruments is totally useless. >> Brent Cobleigh: We have a whole team whose job is to prepare the instruments and do a very precise movement, a choreographed movement, of one instrument off the airplane, another one on. >> Pamela Marcum: Some of them make pictures that will look a lot like something that would have come out of a digital camera, but of course at a different wavelength. Others will not look like a picture at all. [ Music ] >> Brent Cobleigh: One of the biggest challenges, of course, is we're putting a large hole in the side of the airplane. >> Alois Himmes: The telescope in total is 17 metric tons. And there's an additional 3 tons distributed in electronic racks all over the aircraft. [ Music ] >>Eddie Zavala: The telescope as a certain level of precision. The instruments require a certain level of precision and accuracy in order to conduct the science. And the engineering challenge of providing that stability on an airplane that is flying and encountering turbulence is a significant challenge. >> Brent Cobleigh: We had major structural modifications that had to happen. We had to add an additional bulkhead just forward of the telescope so that we can maintain a pressure area where people can work. And then the aft area is vented to the outside as we open the door. >> Alois: Himmes: The telescope is operated when the large door is open, so the environment is not very benign. >> Eddie: Zavala: The telescope is something that is designed to free-float. It floats on a spherical bearing. And that allows the telescope to be somewhat isolated from the movement of the aircraft. Inside SOFIA it's like flying on any other airliner. [ Music ] >> Jim Less: We're planning for about a 10-hour mission, hopefully about eight and a half hours' worth of science out of that. >> Brent Cobleigh: We do preflight checks on all the airplane systems and all the observatory systems. Fuel up the airplane. We go into a crew brief in the late afternoons where the entire team that is going to fly on the airplane gets together and talks about the objectives for the flight, status of all the systems, the weather, and the mission plan ahead. The team goes out and does their preflight checks on the airplane, start engines, we take off, climb to altitude, and do whatever mission is planned for that night. Usually it's about a 10-hour flight. >> Pamela Marcum: We know before we even get on the plane what objects are going to be looked at, at exactly what time in the flight they're going to be looked at. It's all sort of planned out and choreographed like a complicated dance routine. [ Music ] >> Eddie Zavala: SOFIA is a unique blend of aeronautical capabilities, science engineering in the form of a state of the art telescope, and then cutting edge science instruments. >> Brent Cobleigh: We have the U.S. /German partnership, which is 80% U.S. and 20% German. >> Alois Himmes: We are responsible for developing and delivering and support the integration of SOFIA's infrared telescope. >> Eddie Zavala: On board there's probably about 20 to 30 personnel along with USRA personnel, our science support personnel, the mission ops. >> Brent Cobleigh: We also have multiple NASA centers, NASA Ames, primarily responsible for the science, and NASA Dryden (Armstrong) responsible for the aircraft operations. It takes that total group of expertise together that makes SOFIA an operational telescope. >> Cris DeWolf: Sometimes I think that my kids think science is done by some person sitting in a lab or up on a mountain with a telescope all by themselves. Having them see that it is really such a team effort I think is important. [ Music ] >> Alois Himmes: Using instruments from Germany doesn't mean that they can only be used by Germans. So those instruments can be used also by U.S. institutions, by other institutions. >> Eddie Zavala: This facility is not being built for NASA. We are providing it for the science community, for future scientists, and for educators. Through those teachers, they're our airborne astronomy ambassadors program, and they'll be able to extend a lot of what we learn on SOFIA into the classroom. [ Music ] >> Pamela Marcum: SOFIA's science is drive by the demands and the imagination of the community. >> Brent Cobleigh: The thing I get satisfaction over is seeing the teams succeed themselves and whether that be technicians installing electrical components or scientists getting the data that they receive or a teacher getting a good experience on board to take back to their classrooms. >> Pamela Marcum: So SOFIA is considered to be an international resource to be used by the global community of astronomers. >> Eddie Zavala: We hope to truly inspire students, scientists, engineers, mechanics, pilots so anyone in a grade school classroom right now, depending on what their interest is, they can see themselves operating SOFIA in the next 10 to 15 years. >> Pamela Marcum: There are a lot of open science questions that have been open for, quite frankly, a very long time. Creativity and inquiry is what's going to lead SOFIA to discovery and to answering a lot of outstanding questions over the next 20 years of its life. [ Music ]

History

Eclipse chasing

Early attempts

Scientists of Naval Observation with special camera to photograph eclipse from the USS Los Angeles dirigible.[1]

First attempts to observe astronomical objects from planes were made in 1920 from a biplanes. Until 1960, the main objects of such observations were solar eclipses.[2]

In 1923, US Navy tried to observe the solar eclipse of September 10 from sixteen planes, including Felixstowe F5L biplane, "to determine the centerline of the eclipse from air." No photo recorded the eclipse. Officer and photographer Albert William Stevens was one of the pilots on this expedition, he is sometimes called "the father of airborne astronomy".[2] There was another attempt to observe a solar eclipse, this time from a dirigible. On 24 January 1925, U.S. Naval Observatory and U.S. Bureau of Standards gathered a group of astronomers to observe a total solar eclipse from the USS Los Angeles airship over the New York City, with Captain Edwin Taylor Pollock as a head of the group.[3][1] They used "two pairs of telescopic cameras", to capture inner and outer portions of Sun's corona, and a spectrograph. The expedition achieved good publicity, but it was not very successful in its observations - the dirigible was not very stable and the photos were blurred.[4] The next attempt was successful: an expedition of the Naval Observatory to observe the solar eclipse of April 28, 1930 on Honey Lake, California, with Vought 02U-1 plane equipped with a camera, recorded "the approach of the shadow".[2]

Army Air Corps and the National Geographic Society organized another expedition in 1932, to observe the eclipse of August 31. Accompanied by Lieutenant Charles D. McAllister of the Army Air Corps, Stevens took the first photograph of the Moon's shadow projected onto the Earth during a solar eclipse.[5][2][6]

Royal Canadian Air Force observed the solar eclipse of July 9, 1945 from four planes: "a Spitfire, a Mitchell, and two Ansons"; three planes used seven standard aerial photography cameras, "adjusted to automatically take exposures".[2] For the solar eclipse of May 8, 1948, National Geographic society organized several ground stations and two backup planes for a case of bad weather. Two B-29s, stationed on the Aleutian Islands, successfully observed and photographed the eclipse.[2]

After the war

Two United States Air Force colonels inspecting the path of the eclipse of February 25, 1952 in preparation for an expedition to Africa.

For the solar eclipse of June 30, 1954, observations were made "from the open door of a special Lincoln aircraft". Photographs helped "to derive coronal brightness and polarization, along with sky brightness and polarization". Several missions were made in 1960s. Three NC-135 planes of the Los Alamos Scientific Laboratory (LASL) were used for eclipses observations from 1965 to 1980. The planes were operated by the Atomic Energy Commission.[2]

In 1973, the French Concorde prototype, c/n 001, was modified with roof-top portholes for a solar eclipse observation mission of 30 June 1973, at the end of the French testing programme. Observational instruments were installed on board, and the aircraft flew across Africa for 74 minutes in the Moon's shadow. One of the scientists was Donald Liebenberg, who have previously flown on LASL's NC-135.[7][2] The airplane is now at the Le Bourget Air and Space Museum on permanent display in eclipse livery, with the portholes displayed.[8]

NASA used two retrofitted WB-57F jet planes to chase the total solar eclipse of August 21, 2017. Telescopes were mounted on the noses of the planes, that allowed to capture the clearest images to date of the Sun's corona and the first-ever thermal images of Mercury, revealing how temperature varies across the planet’s surface. The high-definition pictures, captured 30 times per second, will be analyzed for wave motion in the corona to see if waves move towards or away from the surface of the Sun, and with what strengths and sizes.[9]

NASA observatories

First NASA airborne observatory, Galileo, was a modified Convair 990. It first flew for the solar eclipse of May 30, 1965. It was named Galileo because during the eclipse Guglielmo Righini [it] spotted the moons of Jupiter from the plane.[2] Galileo was used until 1973, when it was destroyed in a mid-air collision.[2][10] It was used to observe eclipses, comet Ikeya-Seki, planetary IR observations, and Giacobinid meteor showers. Planetary scientist Gerard P. Kuiper performed a series of Venus observations in near infrared[11] and Mars opposition. Galileo II, also a Convair 990, was used for a very short time.[2]

To avoid atmospheric absorption of infrared radiation, Frank J. Low developed devices that could be placed aboard aircraft, first using a Douglas A-3 Skywarrior from the United States Navy that carried a 2-inch telescope in 1965 and 1966.[12] The Learjet Observatory with an open-port 12-inch telescope was proposed in 1966 by Low, and made its first flight in 1968. It allowed to perform infrared astronomy; among other discoveries are "the first measurement of the internal energies of Jupiter and Saturn, far-infrared observations of the great nebula in Orion, studies of star formation regions and the bright IR sources at the center of the Milky Way galaxy", and also to determine the nature of Venus' clouds using a spectrosopy.[2]

The Kuiper Airborne Observatory (KAO), first flown in 1974, consisted of a 36 in (91 cm) aperture Cassegrain reflector carried aloft on a Lockheed C-141 Starlifter jet transport to perform infrared observations. It was named after Gerard P. Kuiper. KAO was operational from 1974 to 1995, and usually flew about 70 flights per year. Among its discoveries are:[2]

discovery of the rings around the planet Uranus; detection of water vapor in comets; discovery of Pluto's atmosphere; the composition, structure, and dynamics of Supernova 1987a; luminosity, dust, and gas distributions in the Galactic Center; emission by shocked gas components of the interstellar medium; and the structure of star-forming clouds.

In terms of aperture, the largest aircraft-borne instrument to date is a 2.7 m (110 in) reflector telescope carried by a modified Boeing 747 for the Stratospheric Observatory for Infrared Astronomy (SOFIA) project. This instrument was put into use for astronomical observation in 2010.[13] On 29 June 2015, the dwarf planet Pluto passed between a distant star and the Earth producing a shadow on the Earth near New Zealand that allowed SOFIA to study the atmosphere of Pluto.[14]

Features

By carrying the telescope to a sufficiently high altitude, the telescope can avoid cloud cover, pollution, and carry out observations in the infrared spectrum, above water vapor in the atmosphere which absorbs infrared radiation. Airplane also allows to place telescope exactly to the needed position.[2] Some drawbacks to this approach are the instability of the lifting platform, the weight restrictions on the instrument, the need to safely recover the gear afterward, and the cost compared to a comparable ground-based observatory.

Airborne observatories are very expensive to operate, because they require a crew, a pilot, and fuel.[15] The cost of running SOFIA observatory per year was nearly the same as of the Hubble Space Telescope.[16]

List of specially-built airborne observatories

Observatory Photo Aircraft Tail# Telescope In-service Out-of-service Notes Refs
NASA Galileo Airborne Observatory
Convair 990 N711NA 1965 1973 Destroyed in a mid-air collision. [2]
NASA Learjet Observatory [de]
Learjet 24B N705NA 31 cm 1966 1974[a] [2][17][18]
NASA Kuiper Airborne Observatory (KAO)
Lockheed C-141A Starlifter N714NA 91 cm 1974 1995 Replaced both Galileo and Learjet, replaced by SOFIA. [18]
NASA-DLR Stratospheric Observatory for Infrared Astronomy (SOFIA)
Boeing 747 N747NA 2.7 m 2010 2022 Replaced KAO. [18]

See also

Notes

  1. ^ last flight

References

  1. ^ a b Maloney, Wendi A. (21 August 2017). "Looking to the Sky: Solar Eclipse 2017 | Timeless". The Library of Congress. Retrieved 9 January 2024.
  2. ^ a b c d e f g h i j k l m n o p Dolci, Wendy Whiting (1997). "Milestones in Airborne Astronomy: From the 1920's to the Present" (PDF). SAE Transactions. 106: 1760–1770. ISSN 0096-736X.
  3. ^ LaFollette, Marcel Chotkowski (24 January 2017). "Science Service, Up Close: Up in the Air for a Solar Eclipse". Smithsonian Institution Archives. Retrieved 9 January 2024.
  4. ^ Aceto, Guy (26 January 2022). "To Catch a Shadow: The Great 1925 Solar Eclipse Aerial Expedition". HistoryNet. Retrieved 9 January 2024.
  5. ^ "Stevens Photographs Eclipse 5 Miles In Air. Army Expert Says That Corona Sprang Into Sight as if Switch Was Snapped". The New York Times. September 1, 1932. p. 10. Retrieved 30 December 2009. Flying at an altitude of five miles near the centre line of the eclipse zone, the aerial unit of the National Geographic Society's eclipse expedition, conducted by Captain Albert W. Stevens and Lieutenant Charles D. McAllister of the Army Air Corps, had an unobstructed view of the eclipse throughout totality. ...
  6. ^ "Albert W. Stevens Photo From 23,000 Feet - Raymond H. Fogler Library - University of Maine". Raymond H. Fogler Library. 14 April 2022. Retrieved 9 January 2024.
  7. ^ Mulkin, Barb. "In Flight: The Story of Los Alamos Eclipse Missions". Los Alamos Science. Retrieved October 21, 2018.
  8. ^ Chris Hatherill (9 March 2016). "When Astronomers Chased a Total Eclipse in a Concorde". Motherboard. Vice.
  9. ^ "Chasing the Total Solar Eclipse from NASA's WB-57F Jets - NASA". July 25, 2017. Public Domain This article incorporates text from this source, which is in the public domain.
  10. ^ "Crash of a Convair CV-990-30A-5 at Moffett AFB: 11 killed | Bureau of Aircraft Accidents Archives". www.baaa-acro.com. Retrieved 9 January 2024.
  11. ^ Cruikshank, D. P.; Kuiper, G. P. (1 January 1968). Arizona-NASA atlas of infrared solar spectrum - A preliminary report (PDF) (Report). Retrieved 9 January 2024.
  12. ^ Overbye, Dennis (June 20, 2009), "Frank J. Low, Who Helped Drive Field of Infrared Astronomy, Dies at 75", The New York Times
  13. ^ "SOFIA - NASA's Stratospheric Observatory for Infrared Astronomy" (PDF). NASA. Retrieved 9 January 2024.
  14. ^ Veronico, Nicholas A.; Squires, Kate K. (29 June 2015). "SOFIA in the Right Place at the Right Time for Pluto Observations". NASA. Retrieved 1 July 2015.
  15. ^ Witze, Alexandra. "Costly SOFIA Telescope Faces Termination after Years of Problems". Scientific American. Retrieved 10 January 2024.
  16. ^ Войтюк, Александр. "Отчего телескопы не летают как птицы". N + 1 (in Russian). Retrieved 11 January 2024.
  17. ^ "History of Airborne Astronomy at NASA - NASA". NASA. 24 September 2018. Retrieved 8 January 2024.
  18. ^ a b c Erickson, E. F. (1 October 1995). "SOFIA: The next generation airborne observatory". Space Science Reviews. 74 (1): 91–100. doi:10.1007/BF00751257. ISSN 1572-9672. Retrieved 9 January 2024.

Further reading

This page was last edited on 10 April 2024, at 18:18
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