APOD: Skylab Over Earth (2013 Aug 18)

[APOD Robot]

Skylab Over Earth

Explanation: Skylab was an orbiting laboratory launched by a Saturn V rocket in May 1973. Skylab, pictured above, was visited three times by NASA astronauts who sometimes stayed as long as two and a half months. Many scientific tests were performed on Skylab, including astronomical observations in ultraviolet and X-ray light. Some of these observations yielded valuable information about Comet Kohoutek, our Sun and about the mysterious X-ray background - radiation that comes from all over the sky. Skylab fell back to earth on 1979 July 11.

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[Chris Peterson]

One very obvious consequence of the shift from film to microchip-based electronic sensors was the demise of the fiducial.

[alter-ego]

One very obvious consequence of the shift from film to microchip-based electronic sensors was the demise of the fiducial.

Yeah, that and some fuzz.

Model T

[rstevenson]

One very obvious consequence of the shift from film to microchip-based electronic sensors was the demise of the fiducial.

For those of us not in the know optically, could you explain why that happened, or more to the point, why it's obvious that it happened? Can't fiducials still be placed within the optical system if desired?

Rob

[neufer]

One very obvious consequence of the shift from film to microchip-based electronic sensors was the demise of the fiducial.

• FIDUCIAL, a. [from L. fiducia, from FIDO, to trust.]
  
  • 1. Confident; undoubting; firm.
    
    2. Having the nature of a trust; as fiducial power.

[b][color=#0000FF][size=110]Fido died still waiting for his master on June 9, 1958. The news of his death was announced to the public by the newspaper on a four-column front page story in La Nazione. On 22 June, La Domenica del Corriere commemorated Fido with a poignant cover story. Fido was buried outside the cemetery of Luco beside his master, Carlo Soriani.[/size][/color][/b]

---

<<Fido (1941 – June 9, 1958) was an Italian street dog that came to public attention in 1943 because of his demonstration of unswerving loyalty to his dead master. Fido was written about in many Italian and international magazines and newspapers, appeared in newsreels throughout Italy, and was bestowed several honors, including a public statue erected in his honor.

Fido probably began life sometime in the autumn of 1941 as an unowned street dog in Luco di Mugello, a small town in the municipality of Borgo San Lorenzo, in the Tuscan Province of Florence, Italy. One night in November 1941, on his way home from the bus stop, a brick kiln worker in Borgo San Lorenzo named Carlo Soriani found him lying injured in a roadside ditch. Not knowing who the dog belonged to, Soriani took him home and nursed him back to health. Eventually, Soriani and his wife decided to adopt the dog, naming him "Fido", a Latin word meaning "faithful one".

After Fido recovered, he followed Soriani to the bus stop located at the central square of Luco di Mugello and watched him board the bus for his job. When the bus returned in the evening, Fido found and greeted Soriani with obvious great joy and followed him home again. This pattern repeated every workday for two years: Fido would stay in the square, avoiding all others, waiting and sniffing the air until excitedly greeting Soriani and enthusiastically following him home.

This was during the Second World War, and on December 30, 1943, Borgo San Lorenzo was subjected to a violent allied bombardment: many factories were hit, and many workers, including Soriani, perished. That evening, Fido showed up as usual at the bus stop, but obviously did not see his beloved master get off. He later arrived back home, but for fourteen years thereafter (more than 5,000 times) until the day of Fido's death, he went daily to the stop watching and sniffing the air in vain for Soriani to get off the bus.

Media interest in Fido grew during his lifetime. Italian magazines Gente and Grand Hotel published the story of the dog, which also appeared in several newsreels of the Istituto Luce. Henry Luce's Time magazine wrote an article about Fido on 1 April 1957. At the end of 1957, a monument entitled "Monument to the dog Fido", was placed in Piazza Dante in Borgo San Lorenzo, next to the municipal palace. Under the statue depicting the dog is the dedication: A FIDO, ESEMPIO DI FEDELTÀ (TO FIDO, EXAMPLE OF LOYALTY).>>

<<Fido is a 2006 Canadian zombie comedy film. The film takes place in a 1950s-esque alternate universe where radiation from space has turned the dead into zombies. This resulted in the "Zombie Wars", where humanity battled zombies to prevent a zombie apocalypse, with humanity the ultimate victor. The radiation still plagues humanity, as all those who die after the original contamination turn into the undead, unless the dead body is disposed of by decapitation or cremation. In order to continue living normal lives, communities are fenced with the help of a governing corporation named Zomcon. Zomcon provides collars with accompanying remote controls to control the zombies' hunger for flesh so as to use them as slaves or servants. In the town of Willard housewife Helen Robinson buys a zombie in spite of her husband Bill's zombie phobia. Their son, Timmy, befriends the zombie, naming him "Fido", a Latin word meaning "faithful one". Based on 69 reviews Rotten Tomatoes gave the film a 70% "Fresh" rating. However, Richard Roeper gave it a resounding 'two thumbs down.'>>

[neufer]

[img3="Hasselblad 500EL/M "20 years in space" anniversary edition with
70mm back, similar to the ones used in the Apollo Program."]http://upload.wikimedia.org/wikipedia/e ... Ullism.jpg[/img3]

<<Victor Hasselblad AB is a Swedish manufacturer of medium-format cameras and photographic equipment based in Gothenburg, Sweden. Perhaps the most famous use of the Hasselblad camera was during the Apollo program missions when man first landed on the Moon. Almost all of the still photographs taken during these missions used modified Hasselblad cameras. The Hasselblad cameras were selected by NASA because of their interchangeable lenses and magazines. Modifications were made to permit ease of use in cramped conditions while wearing spacesuits, such as the replacement of the reflex mirror with an eye-level finder.

The first modified (in fact simplified) Hasselblad 500C cameras were used on the last two Project Mercury missions in 1962 and 1963. They continued to be used throughout the Gemini spaceflights in 1965 and 1966. Three 500EL cameras were carried on Apollo 11. An even more extensively modified Hasselblad EL Data Camera (HDC), equipped with a special Zeiss 5.6/60 mm Biogon lens and film magazines for 150–200 exposures, was used on the Moon surface on the Apollo 11 mission. All following NASA missions also had Hasselblad cameras on board. During the Space Shuttle period cameras based on the 500 EL/M, 553 ELX, 205 TCC and 203 FE have been used. Twelve Hasselblads remain on the lunar surface.>>

[b][color=#0000FF]An accidental exposure from the Hasselblad Lunar Surface Data Camera.[/color][/b]

---

<<A Reseau plate is a transparent plate with fiduciary markers placed at the focal plane of a camera just in front of the film to provide a means of correcting images to enable them to be used for precision measurement. The crosshairs visible in photos taken on the Moon are an example of this usage. Potential distortions include the incorrect position of the film in the camera, the distortions of the film by the development process, and (if digitally scanned) the nonlinearity of the image scanner. These errors may be visually imperceptible but limit the precisions of measurements. Because the position of the marks is very precisely known, the image can easily be corrected to account for these effects. When used for photogrammetry, multiple images can be combined using the fiducial marks and knowledge of the camera geometry to enable measurement of distances between objects in the images.

The Hasselblad Lunar Surface Data Camera was fitted with a Reseau plate. The Reseau plate was made of glass and was fitted to the back of the camera body, extremely close to the film plane. The plate was 5.4 x 5.4 cm in the film plane, which was the useful exposure area on the 70 mm film. The Reseau plate was engraved with a 5 x 5 grid of crosses. The intersections of the crosses were 10 mm apart and accurately calibrated to a tolerance of 0.002 mm. Except for the double-sized central cross, each of the four arms on a cross was 1 mm long and 0.02 mm wide. The crosses (also known as fiducials) were recorded on every exposed frame and provided a means of determining angular distances between objects in the field-of-view. When the Hasselblad Lunar Surface Data Camera was fitted with a 60 mm lens, the images of the reseau crosses on the film have an apparent separation of 10.3 degrees. With a 500 mm lens fitted, the apparent separation is 1.24 degrees.>>

[Chris Peterson]

For those of us not in the know optically, could you explain why that happened, or more to the point, why it's obvious that it happened? Can't fiducials still be placed within the optical system if desired?

Fiducials can still be used, and are in certain cases. But their primary use as we see them with old space images was to overcome the geometric instability of film. That's not an issue with CCDs and CMOS image sensors, which have their pixel positions very well defined mechanically. But film distorts, so if you want to convert the position of something on that film to its actual position in the scene, the uncertainty can be quite high. That's one reason that glass photographic plates were normally used for telescopic imaging, but even those are much less dimensionally stable than CCDs- the emulsion itself can change position over time on a glass photographic plate.

Fiducials are still used with electronic imaging systems, but to provide geometric references at places other than the image plane. You might find them on a microscope slide, or on a manufactured object that gets scanned. But it would make no sense to place a fiducial plate directly over a CCD in the way it was placed over the film in the cameras used by the astronauts.

[Tara_Li]

*vaguely wonders why this discussion on alignment marks didn't take place in a separate thread over where the camera nuts hide*

It's kind of sad, really, that we never launched Skylab B. Or a Skylab C. Three of them would give us as much pressurized volume as the ISS currently has. And since they'd all be pretty much identical, more launches would allow assembly line techniques to come into play, helping to reduce the costs of building... and of building the launch vehicles themselves. Who knows how much we could have learned from having people actually *WORKING* in space, with astronauts gaining hundreds of days on orbit and several hundred hours each working outside in freefall and vacuum. Skylab - a mostly wasted opportunity. *sighs*

[Chris Peterson]

*vaguely wonders why this discussion on alignment marks didn't take place in a separate thread over where the camera nuts hide*

Camera nuts reside on all threads! And the discussion is here, because this is the image that features the fiducial marks.

[Beyond]

Where would the Asterisk* be without camera nuts No APOD, for one.Without the camera nuts to 'snug-up' the pictures, all the information would just fall apart. A picture is worth 1000 words and puts the words into a perspective that we can see, even if we don't understand it all.

[neufer]

It's kind of sad, really, that we never launched Skylab B. Or a Skylab C. Three of them would give us as much pressurized volume as the ISS currently has. And since they'd all be pretty much identical, more launches would allow assembly line techniques to come into play, helping to reduce the costs of building... and of building the launch vehicles themselves. Who knows how much we could have learned from having people actually *WORKING* in space, with astronauts gaining hundreds of days on orbit and several hundred hours each working outside in freefall and vacuum. Skylab - a mostly wasted opportunity. *sighs*

[b][color=#0000FF]Map of the Skylab reentry site and final orbits as predicted by NASA [/color][/b]

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<<The Skylab program cost $2.2 billion from 1966 to 1974, or $10 billion in 2010 inflation-adjusted dollars. As its three three-man crews spent 510 total man-days in space, each man-day cost $19.6 million in 2010 dollars, compared to $7.5 million for the International Space Station. Skylab was abandoned in February 1974, but to welcome visitors the crew left a bag filled with supplies and left the hatch unlocked.

Skylab's demise was an international media event, with merchandising of t-shirts and hats with bullseyes, wagering on the time and place of re-entry, and nightly news reports. NASA calculated that the odds of station re-entry debris hitting a human were 1 to 152, although the odds of debris hitting a city of 100,000 or more were 1 to 7 and special teams were readied to head to any country hit by debris and requesting help. In the hours before re-entry, ground controllers adjusted Skylab's orientation to try to minimize the risk of re-entry on a populated area. They aimed the station at a spot 1,300 km south southeast of Cape Town, South Africa, and re-entry began at approximately 16:37 UTC 11 July 1979. The station did not burn up as fast as NASA expected, however. Due to a 4% calculation error, debris landed southeast of Perth, Western Australia, and was found between Esperance and Rawlinna. The Shire of Esperance facetiously fined NASA A$400 for littering. The fine was eventually paid in April 2009, when radio show host Scott Barley of Highway Radio raised the funds from his morning show listeners and paid the fine on behalf of NASA.>>

[b][color=#0000FF]The unused Skylab B module (S-IVB 515) is on display at the National Air and Space Museum in Washington D.C.[/color][/b]

---

<<Skylab B was a proposed second US space station similar to Skylab that was planned to be launched by NASA for different purposes, mostly involving the Apollo–Soyuz Test Project, but was canceled due to lack of funding. Two Skylab modules were built in 1970 by McDonnell Douglas for the Skylab program, originally the Apollo Applications Program. The first was launched in 1973 and the other put in storage.

Some uses considered for the second Skylab module included putting it into a mode where it could generate artificial gravity and a plan to celebrate the 1976 United States Bicentennial with the launch of two Soviet Soyuz missions to the back-up Skylab.

When the Apollo–Soyuz Test Project was created in 1972, NASA had also considered launching the back-up Skylab station during the ASTP mission in 1975, which would involve the Apollo spacecraft docking with the Soyuz spacecraft first, performing intended operations, then heading for the Skylab B, which during the ASTP discussion was originally called the International Skylab, for a 56–90 days extended mission.

For future missions, the station, which would have then be called the Advanced Skylab, could have been expanded by the Space Shuttle, which was due to enter service in 1979. At the time the idea was discussed, NASA still had two Saturn V launchers, three Saturn IB boosters, the back-up Skylab space station, three Apollo CSMs and two Lunar Modules in storage.

However, after the first Skylab was launched in May 1973, the plan for the Skylab B was canceled and the Apollo/Soyuz spacecraft had to use the Docking Module launched on the Apollo-Saturn IB for performing experiments in space. After Project Apollo ended and as NASA was moving to developing the Space Shuttle, the remaining Apollo hardware was donated to museums in 1976.>>

[Adolfo Domínguez]

I must say that this discussion has been the most interesting for me. In fact, I've learned a lot.
Fido's history has touched my heart almost to tears.
If I've understood well, today's APOD image should have had these fiducials, and actually it doesn't, so one's not able to discriminate sizes - I mean dimensions - and distance.

[neufer]

If I've understood well, today's APOD image should have had these fiducials, and actually it doesn't,

You've understood well, but you haven't looked very well.

[Chris Peterson]

If I've understood well, today's APOD image should have had these fiducials, and actually it doesn't, so one's not able to discriminate sizes - I mean dimensions - and distance.

This image does have fiducial marks, as we'd expect for an image from that time, made on film. And the film is certainly stable enough that dimensional information can be inferred from the image, just not with quite the same degree of accuracy as would be possible with an image made with an electronic sensor.

[rstevenson]

For those of us not in the know optically, could you explain why that happened, or more to the point, why it's obvious that it happened? Can't fiducials still be placed within the optical system if desired?

Fiducials can still be used, and are in certain cases. ... .

Thanks Chris. Very informative.

Rob

[owlice]

I must say that this discussion has been the most interesting for me. In fact, I've learned a lot.
Fido's history has touched my heart almost to tears.

Me, too.

[Chris Peterson]

I must say that this discussion has been the most interesting for me. In fact, I've learned a lot.
Fido's history has touched my heart almost to tears.

Me, too.

Heart, touched by FIDOcial markers.

3189148_1752-1947-5-470-9.png (41.88 KiB) Viewed 6672 times

[neufer]

I must say that this discussion has been the most interesting for me.
In fact, I've learned a lot.
Fido's history has touched my heart almost to tears.

Me, too.

Are we talking Fido the dog or Fido the zombie

[geckzilla]

Some uses considered for the second Skylab module included putting it into a mode where it could generate artificial gravity and a plan to celebrate the 1976 United States Bicentennial with the launch of two Soviet Soyuz missions to the back-up Skylab.

Artificial gravity. It's something that still hasn't been done yet, right? I should probably get to work on my plans for the ISS (International Sports Stadium) which has a large arena within and variable gravity control so that different types of sports can be played with weird gravity modes.

[neufer]

Some uses considered for the second Skylab module included putting it into a mode where it could generate artificial gravity and a plan to celebrate the 1976 United States Bicentennial with the launch of two Soviet Soyuz missions to the back-up Skylab.

Artificial gravity. It's something that still hasn't been done yet, right?

Not intentionally: http://asterisk.apod.com/viewtopic.php? ... 55#p201255

[Boomer12k]

When you look at Skylab...you realize how intrepid we can be....

:---[===] *

[Adolfo Domínguez]

If I've understood well, today's APOD image should have had these fiducials, and actually it doesn't, so one's not able to discriminate sizes - I mean dimensions - and distance.

fid.jpg

This image does have fiducial marks, as we'd expect for an image from that time, made on film. And the film is certainly stable enough that dimensional information can be inferred from the image, just not with quite the same degree of accuracy as would be possible with an image made with an electronic sensor.

Sorry! Didn't see the fiducial marks on APOD image the first time and submitted my post. After returning the second time I noticed them but decided to wait some answer, anyway.
Thanks, Chris. Your posts have made this point clearer for me. Enoyed "heart touched by FIDOcial marks. Excellent!

Adolfo

[DavidLeodis]

That's a great photo. I particularly like the clouds on the left side.

The photo makes it look like Skylab has rotating blades, like an helicopter. The single panel on the right looked odd until I read in the explanation to the photo (brought up through the "picture above" link) that "Complete loss of one of the solar arrays happened at 593 seconds when the exhaust plume from the S-II's separation rockets impacted the partially deployed solar array system". It all made Skylab looking like a fly with one wing missing!

[neufer]

[b][size=150][color=#0000FF]Howdy Doody Air-O-Doodle[/color][/size][/b]

---

The photo makes it look like Skylab has rotating blades, like an helicopter. The single panel on the right looked odd until I read in the explanation to the photo (brought up through the "picture above" link) that "Complete loss of one of the solar arrays happened at 593 seconds when the exhaust plume from the S-II's separation rockets impacted the partially deployed solar array system". It all made Skylab looking like a fly with one wing missing!

[Beyond]

Cowabunga It looks like part of Howdy Doody's car-train-boat-plane is missing. I hope it doesn't crash-de-rail-sink-crash.