 |  | | | | Space Shuttle Re-entry Video Procedures for Space Enthusiasts
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08.05.05
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Amateur astronomers have observed satellites and other space craft since the dawn of the Space Age. Video Astronomy is a rapidly growing segment of the amateur astronomy community and is yielding impressive results. Indeed, dedicated amateurs have even succeeded in obtaining high power telescopic images of the ISS and its predecessors with excellent resolution using home camera/video equipment and software.
When the Space Shuttle Columbia reentered the Earth's atmosphere during the STS-107 mission, amateurs astronomers were on hand to record its troubled flight. Photometric analyses of the better videos of the reentry were able to establish the timing of early spacecraft failure and provide data allowing for the calculation of sizes of some of the early debris pieces prior to the Columbia’s final breakup. This information helped to understand and confirm the early events leading to breakup. The STS-107 work is documented in the Columbia Accident Investigation Board report, volume 3, part 2, section 6.
NASA anticipates a wide interest in the public's observations of the STS-114 Space Shuttle mission. Space Shuttle viewing information can be found on the following site: http://spaceflight.nasa.gov/realdata/sightings/index.html. Decisions for launch, reentry and landing are made with regard to weather and other mission-related factors so that it is not always possible to anticipate in advance the reentry timeline and ground track. At the present time NASA does not plan to overfly the USA during reentry. By monitoring the NASA select television channel or by checking the site listed above, you can follow the progress of the mission and the decision making in near real-time.
Although it is possible to view a spacecraft reentry with the unaided eye, it is not possible to see the Shuttle reentry if the reentry flight path is in broad daylight since the plasma trail created as the Shuttle passes through the atmosphere is not bright enough to contrast with the sky. Naked eye viewing of the reentry itself is best when the observer's site has very clear skies, and the observer is in complete darkness or very close to local sunrise or sunset if you know precisely where to look.
Even if you know you cannot see the Shuttle reentry due to lighting or cloud problems, it is possible to hear the double sonic boom from the Shuttle if it is not too far away. It takes sounds about 1100 feet/sec (300m/s) to propagate to the ground; thus if the Shuttle is 200,000 feet (60,000m) away from you at its closest distance during reentry along your line of sight, it would nominally take around 96 seconds for the sound to reach your ears AFTER the shuttle passed that point. For the human ear to detect the boom(s) you should be far away from noises, especially traffic noise.
Video Tips
Please Note: At the present time, NASA is NOT soliciting imagery of the Shuttle from the public. If this changes, information will be posted on this web site.
NASA's photometric analyses of the videos that were graciously submitted by the public highlighted several important procedural details that amateur astronomers use to produce excellent results. Scientists who worked with those videos of Columbia compiled the following tips for video observations of the Shuttle. These tips are summarized as quick-reference checklists below. Several internet links for additional information are also provided.
- First, plans require knowledge of the times and travel path of the spacecraft. Observing times, flight paths, and orbital elements are available on websites for most satellites.
- Use a sturdy tripod. It is impossible to handhold a camera with a long lens steady enough to get good images. Furthermore, one needs to practice a bit ahead of time.
- Practice tracking distant objects. Try panning with a video camera on the tripod while following an airplane or satellite across the sky. Keep the motion as smooth as possible while keeping the target near the center of the field of view. This is not as easy as it sounds but smooth tracking will come with practice. Avoid jumping back and forth to perfect the centering. Use the eyepiece on the camera or an attached finder scope since tracking from a monitor is harder than it sounds. If possible, place the tripod so that the complete flight path from horizon to horizon is unobstructed. Document any visual obstructions like trees, houses, telephone poles that appear in the field-of-view.
- Avoid changing the camera zoom. Fixed focal length lenses are best for collecting videos that are used for measurements, but most camcorder systems have zooming lenses. It is difficult to make measurements from the images when you don’t know the focal length of the lens. It is even harder when the focal length is always changing. For all camcorders the digital zoom should be turned off to avoid the artifacts and the loss of information created by digital zoom. In practice, the camera should be set at wide until the shuttle is spotted then it should be zoomed to maximum optical zoom and kept there. This way the focal length and therefore the plate scale only needs to be determined for this one known zoom position. At maximum optical zoom the field of view of most video cameras is similar to that of binoculars.
- If possible, the auto-focus should be turned off and the camera manually focused on a celestial object. Good focus is very important and can be judged in a dark sky by the number of stars seen in the image. Tape the focus so it doesn’t change by accident.
- Lens aperture and exposure should be set to record only a few bright stars in the field of view to limit the saturation of the bright shuttle reentry image.
- Prepare a checklist for the observation and document your work.
Camera Equipment
Many home camcorders can be used to collect good videos of spacecraft. Good videos of the STS-107 re-entry were obtained from a wide range of commercial camcorders in "night-shot" mode as well as with several professional color cameras. Any camera which can image a few of the brightest stars will work since the shuttle at reentry is actually quite bright. With stars, the focus is very important.
Even better than a camcorder is a "scientific grade" black and white video camera such as those used for astronomical observations. Amateur astronomers buy from several manufacturers of such cameras. Scientific video cameras should be fitted with a high quality fixed lens that provides about a 3 to 5 degree “binocular” field of view. In most cases, a carefully aligned finder scope firmly attached next to the camera is needed to track the shuttle since tracking from a video monitor is much more difficult than it sounds. Mounting a camcorder alongside a scientific grade camera allows one to record voice notes and a time signal in the background on the audio track with perfect time synchronization. This makes documentation of the event easier.
Whatever camera is used, one should follow the suggested observing checklist below.
Camera Set-Up Checklist
- Use a good quality camcorder. Digital is preferred since copied tapes are the same quality.
- Research the apparent flight path as seen from your site. Choose the viewpoint to allow an unobstructed view of as much of the flight path as possible. Be prepared for alternate landings.
- Use a tripod. Practice smoothly tracking airplanes and/or satellites at max optical zoom to improve your technique. Be prepared for overhead passes and practice tracking through or around the zenith.
- Don’t zoom in and out. If necessary, acquire at wide zoom and then go quickly to max optical zoom and stay there. Disable the digital zoom feature on your camera.
- Turn off autofocus and manually focus on infinity. Focus on a star at max zoom before the event and don’t change the focus. If necessary, use masking tape to prevent changing the focus.
- Use normal or nightshot mode - not super nightshot (since it integrates). If using nightshot, turn off the IR illuminator if possible to avoid seeing bugs fly by.
- If a choice of exposure time is available, use as long an exposure as possible. This should be 1/60 second for standard 30 frames per second video.
- With scientific grade cameras, set the gamma to 1. Set the gain to show 2nd magnitude stars and don’t change it. Use the longest focus lens you can without causing jitter and blurring during tracking (probably around 50mm).
Documentation Checklist
- Make notes. Write down your procedures and, if possible, record settings and a real time commentary on the recorder’s audio track. When using a scientific grade camera, take a short video of the panel on the controller recording the instrument settings.
- Add time synchronization in the recorded sequence. If possible, record the screen of a GPS receiver on video before or after the event or record the WWV shortwave time signal on the audio track during the event. Time code should be displayed in the video (for the non-digital cameras) just before or after the event without stopping the camera.
- Record the site conditions. Before or after the event and without moving the tripod, shoot some video along the flight path in daylight. This allows us to determine if trees, utility poles, or wires may have interfered.
- Record the weather and observing conditions, including clouds, haze, lights. Shoot some video in super nightshot or in twilight (if within a few minutes of the event) so we can determine the presence of clouds. Slowly pan along the flight path.
- Make a copy of the tape for your archives. If tapes are sent to NASA, they require the originals for analysis so keep your copy as a backup.
MORE REFERENCES
Satellite Observing Times
First go to the Canadian Meteorological Center’s excellent Clear Sky Clock site:
Choose your observing site: For example, Huntsville, AL or the VBAS.
From your observing site’s clear sky clock a wealth of resources are available:
- Go to Satellite Predictions: your clear sky clock site is the default.
Choose predictions. For example 10 day ISS
Get sky chart for the observation
- Go to CalSky: If you link from ClearDarkSky, your site will be the default
This is a rich site and needs some time to get to know it.
Select Satellite in the banner then select Space Shuttle.
Fill out the observing plan and wait for the sky chart.
Other observing tools
Examples of Shuttle and ISS Images
Shuttle imaging links:
http://www.randomuseless.info/shuttleentry/shuttleentry.html
http://www.rgj.com//news/files/2003/02/01/21413.mov
ISS imaging links:
http://www.fortunecity.com/victorian/canterbury/222/satellite.htm
http://www.analemma.de/english/issphot.html
http://astro.umsystem.edu/apml/ARCHIVES/AUG01/msg00863.html
http://satobs.org/seesat/Aug-2001/0197.html
On-Line Resources
Telescopic Satellite Tracking
Satellite Tracking Tools
- STSPlus observing software by David Ransom
- Satellite Tool Kit is a professional spacecraft planning tool for free.
Note that one must register to be able to login to their excellent database.
- J-Track from MSFC science@nasa
Two Line Element set (TLE) sites
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