Introduction
Space debris continues to fall from the sky on a regular basis. Much of this goes unreported either because little attention is given to it by casual observers or reentries are seen from places where few people live or because eyewitnesses simply do not know what they are seeing. Meteors, which are natural debris, fall daily and are seen as fast moving streaks though some times as brilliant fireballs.
Artificial satellites are more rare but can appear as a single object that transforms into a procession of slow moving lights. We encourage all readers to provide an accurate report online as soon after seeing such an event using the form found below in this page.
Note that observations of UFOs or meteors are not being requested. A spacecraft reentry has a unique signature as described above and it will be quite obvious if you see such a group of objects traveling together in formation with some disappearing while others continue in parallel flight paths.
A UFO (unidentified flying object) can be interpreted in a number of ways. Stars, planets, the Moon and Sun are all essentially stationary objects. The only reason they seem to ‘move’, is that the Earth rotates slowly and collectively they change their position in the sky gradually throughout the night (or day). Flying objects may consist of individual birds or flocks of birds, bats, airplanes, possibly balloons, lanterns, even glowing insects like fireflies. Other moving objects are generally star-like and these are normally spacecraft and other satellites in Earth orbit. Airplanes flying from one place to another may appear star-like but are often accompanied by adjacent red or blue lights. Most untrained observers are not able to tell what they are seeing. Thus, a UFO to one person may not be a UFO to another. Many reports of UFO’s can be linked to streaks in the sky that are most often spotted after sunset or before sunrise. These are usually linked to rocket launches and can be spotted soon after launch or minutes or hours after a launch in relation to rocket stage separation. Still others might be classified as ‘unexplained’. This site does not accept reports of this nature and the reader must think through carefully prior to submission.
Collection of evidence is crucial to any report. A video taken with a camera mounted on a stable tripod and clearly focused is a valuable tool to support any investigation along with accurate time and location details.
SRW Objectives
The objective of SRW is mainly educational one. We aim to spread awareness on this subject to the general public and the astronomical community through the following methods:
- Send alerts to our members before an expected reentry.
- Ask the interested members to observe an expected reentry and report back their sighting.
- Discuss this subject in the mailing list of SRW to increase the knowledge of the members.
- Send news reports to the media, if required, about major reentries that were witnessed over large areas.
Who Are We?
SRW is a collaboration program between international experts in the field of artificial satellites and the International Astronomical Center (IAC). Any interested person is welcome to join the program. SRW is moderated by four supervisors, who are (Sorted Alphabetically):-
- Joseph Remis: Expert in satellite reentry predictions.
- Mohammad Odeh: IAC director.
- Paul Maley: Space debris and satellite observer.
- Ted Molczan: Expert in artificial satellite observations.
- T.S. Kelso: Professional expert in satellite tracking and observation.
Join Our Mailing List
We have created a dedicated mailing list for SRW, where interested members can join it and start discussions and share their knowledge. We will send reentry alerts to this mailing list as well. Kindly click on the link below to join the mailing list (Group).
Important Note: If you wish to receive the emails of the mailing list, then after you click on “Join Group”, please make sure to change your subscription type from “Don’t send email updates” to “Send me an email for every new message”.
FAQ
Below are some Frequently Asked Questions (FAQ) regarding satellite reentries.
- How many satellites orbit Earth? and how many of which are operational?
A: This number is constantly changing as new satellites are launched and others resented the atmosphere. As of the beginning of 2014 USSTRATCOM tracks more than 22,500 objects orbiting Earth. About 05 percent of those being tracked are active payloads, 08 percent are rocket bodies, and about 87 percent are debris and/or inactive satellites. Out of the 22,500 USSTRATCOM tracked satellites, about 17,000 are available to the public. According to “SATCAT Boxscore”, as of 03 March 2014, there are 3889 payloads (1315 only are active), and 13010 debris orbiting Earth. - Why do satellites decay and will all of them reenter Earth?
A: Satellites that are launched into Earth orbit decay due to the effects of gravity, solar radiation pressure, lunar and solar perturbations and interaction with the atmosphere. Generally speaking, the higher the overall orbit, the longer the satellite will remain in orbit. Satellites in geostationary orbit will remain there and not decay. - What happens to a satellite during reentry?
A: As the object begins to descend from orbit it encounters layers of molecules that compose the atmosphere. As the density increases, the object begins to heat up during to its velocity. The weakest pieces of structure, and also lighter parts, begin to break off. Some will disintegrate quickly with others taking more time. Explosions may or may not occur. Some pieces may survive reentry and others may skip back up into orbit reentering some hours or minutes later. - How does the reentry look like in the sky?
A: A reentry has the following appearance. A single star like object moving slowly through the sky will accelerate. Multiple objects will begin to appear until a long procession of objects can be observed. Some appear and disappear quickly while others linger. The whole process, depending upon when you first spotted it, could take from maybe 20 seconds to a minute, but these times could be also longer or shorter in duration. The objects may appear white, yellow, orange, red or blue depending upon how your eye perceives them.A smoke train may be left in the wake of a reentering satellite path lasting a fraction of a second to many seconds in length, but this phenomenon is more closely connected to bright fireballs. Sounds such as sonic boom(s) may accompany the passage of either a very bright fireball or a very spectacular satellite reentry. The term ‘satellite reentry’ applies to satellites, rockets or other pieces of man-made space debris. - What are the most common types of space objects that survive reentry?
A: Titanium pressure spheres have a very high melting point and are the most common objects found to survive reentry. - What are the definitions of some terms used in a reenty event?
A:- Reentry Trajectory: is the end of the final orbit where the decaying object is burning while going down. The length and the time of course of this trajectory depend on the object. Example: for a rocket body this trajectory is some 1000-2000 Km long and has a 2-4 minutes duration while altitude decreases from 130 to 80 kms.
– Reentry Viewing Location: it’s the location on earth from which the burning decaying object is visible. It is approximately one circle centered on trajectory down points and of some 1000 Km in diameter.
– Debris Footprint is at the end of the trajectory down points the location where surviving debris could impact earth.
– Impact Location is a point at the end of Footprint where an impact of a decaying object occurs.
- At what altitude does a satellite begin to reenter the atmosphere?
A: A satellite starts to reenter around 400,000 ft (80 miles or 128km). Low melting point materials melt first, exposing other objects to the extreme heat and forces of reentry. As pieces melt or break away, the heating and deceleration loads increase, further breaking the object apart and creating multiple pieces of debris. - When (from which altitude to which altitude) I can see the reentry?
A: The reentry may be seen from an altitude of approximately 128km to a much lower altitude, perhaps as low as 40km. These altitudes are not precise and are rough indicators based on atmospheric density. - Where might debris from a reentry land?
A: The area where debris might land is called the debris footprint. The heel of this footprint is approximately located under the breakup point, and its toe might extend up to 2000 km downrange (that is, in the direction of the flight path); the width of the footprint varies from 20 to 40 Kms. - Does the expected reentry location mentioned in the predictions represent the same location where the debris might hit Earth?
A: No; “reentey location” is not as same as “impact location”. Reentry location/time might differ from organization to another. Some organizations define the reentry location/time as the location/time at which the altitude of the satellite is 80 Kms, others might adopt the altitude as 10 Kms Instead of 80 Kms. Generally speaking, people start to see the reentry when the altitude of the satellite is around 128 Kms. The breakup of reentering objects typically occurs around an altitude of 80 Kms above the Earth’s surface. The heel of “Debris Footprint” is approximately located under the breakup point, and its toe might extend up to 2000 Kms after the footprint’s heel along the satellite path, in a band its width varies from 20 to 40 Kms. - Why do you refer to ‘reentry’? What does this mean?
A: Most man-made objects were manufactured inside the Earth’s atmosphere. As a result they were initially inside the atmosphere. When sent into space they went outside the atmosphere. Hence the term ‘reentry’ is correct. - Are reentries more likely to be seen in Europe or North America than in Africa or the Middle East?
A: Not really. Most satellite orbits lie between latitude 28 and 82. Most of Earth’s inhabitants live in that range of latitude either north or south of the equator. - How often does a satellite reentry occur?
A: For tiny debris: From 0 to 5 per day. For payloads, rockets and big debris (Radar Cross Section > 0.5 m²): approximately one per week. - What sizes of space objects create visible reentry tracks in the sky?
A: Objects from centimeters in diameter or larger are potentially capable of being seen by ground observers. Smaller objects than this are typically the average meteor streak. - Can reentries be seen in daylight?
A: Generally, no. Brilliant fireballs (meteors or small asteroids) may on rare occasion be seen in daylight. - Is it true that a reentry can only be seen far from city lights?
A: No, reentries have been witnessed from brightly lit stadiums as well as from inside urban areas at night. - How accurate are satellite reentry predictions?
A: Reentry predictions are inaccurate for many reasons: the main one is the variation in the density of the upper atmosphere depending on solar activity. The orbital elements used for predictions are also inaccurate due to errors in the observations (mainly radar) used to compute them. The uncertainty is approximately 20% of the remaining lifetime of the object. But the time of decay for a given location is only ± 2min of the last predicted pass over this location. Clearly you do not provide accurate time of decay, but the actual time will correspond to a precise visibility location. - If I go out and look for a reentry during the suggested window of time and do not see anything, is this information of any value?
A: Yes, if the sky was clear and you were looking consistently during the suggested time period and did not spot the reentry, this negative observation tells us that the reentry did not occur from your geographic location and on that predicted orbit. It may be used to confirm other negative or even positive observations and place limits on the actual reentry zone. - I know a reentry was witnessed years ago from my country. Would SRW be interested in such old information?
A: Yes. There may be accounts of reentries or even space debris found and left in a museum which was not widely reported. Please send that to us. - Is a reentry considered dangerous?
A: After more than 50 years of space launches, very little damage or injury have been reported as a result of reentering space objects. The odds of being killed or injured by a piece of space debris are quite small but not completely zero. Damage or injury could result from the velocity at landing and mass of the landed object. Danger could exist if the object contains radioactive material -quite rare- or hypergolic propellant or other chemicals that could be toxic or explosive. - Why are observations of reentries important?
A: To better understand where and when a particular space object came down. This may help quantify reentry prediction accuracy or enable identification or discovery of space debris. They are important to those attempting to study the cross range and down range dispersions of fragments and composition of objects that survive reentry. - If you have been alerted to a reentry, should you contact the media?
A: No. The reliability of most reentry predictions is quite poor. Alerting the media is likely to be a non-productive effort unless you are very lucky. - Should you not rely on testimony from police or military officials over civilian accounts?
A: No. There may be politically motivated and sanitized reports provided from such ‘official sources’. It is better to have independent eyewitness reports to help corroborate ‘official’ accounts. - Can you rely on eyewitness accounts from people who have no experience observing at night?
A: No. We take reports from amateur or professional astronomers more seriously than untrained eyewitnesses. Most untrained observers really cannot identify objects in the night sky, especially if their appearance is short-lived. - If you find genuine space debris, does it belong to the finder?
A: This can be an interesting topic. Some genuine pieces of space debris may contain markings that might enable identification in Cyrillic, English or another language. In other cases no markings such as numbers and letters will appear. It can be embarrassing for a launching nation or entity to admit that a piece of debris has survived reentry especially if it caused or could have caused damage or injury. There is implied legal liability. Thus it may be that no one will claim it is theirs. If it falls on private property, then it is likely the owner of that property has right of initial ownership. You should consult international laws governing ownership of recovered space debris. - Does recovered space debris have monetary value?
A: It may on sites like eBay. But the real value may lie in scientific analysis by entities such as NASA. - What Should I do when I see a suspected reentry event?
A: Attempt to eliminate if your sighting was a meteor or UFO or aircraft given our advice. If you can safely eliminate these options and the appearance was similar to the reentry description, then please file report. - How do I know if what I see is a meteor, airplane, satellite reentry or UFO?
A: A meteor may move quickly across a small or large portion of the sky in a matter of a fraction of a second to perhaps as long as 10 seconds—but longer in extreme cases. It may appear in any part of the sky and move in any direction. A bright fireball may have similar appearance and could break into 2 or more pieces. Meteors may appear individually or as part of a meteor shower.A satellite in orbit may appear to travel in the direction of the Earth’s rotation — west to east, southwest to northeast, north to south or south to north. This is because most satellites are launched into orbits using the Earth’s rotation to expend less energy than if launched against the Earth’s rotation –retrograde. Usually a satellite is seen as a singular object when in orbit. A satellite reentry’s appearance is described by another FAQ.
An airplane may appear star-like and appear anywhere in the sky. Sometimes you can hear sound from engines as the plane passes over. The star like object may be flanked by a red light on one side and blue light on the other, with all three lights moving close together and parallel.
A UFO is something other than these descriptions. It may involve one or more stationary or moving lights of single or variable color. Movement might be sporadic or quick. The position may change or not. It may fade and then reappear. It may also appear like a small or large cloud in an otherwise clear sky. These are just some of the many forms of UFOs. Direction and speed are not predicted nor is duration. These may be spotted closer to military bases or rocket launch sites or proving grounds but others can appear any place or time, day or night. We are not in a position to investigate so please do not report them.
- If I saw a glowing object as being red, but someone standing next to me saw it as green, what does that mean?
A: Each person’s eyes have a somewhat different way perceiving a bright object against a black background. Some people have poor color perception or night vision, may suffer from astigmatism or not be using glasses or contacts as they should at the time of observation. It is often difficult to have universal agreement amongst eyewitnesses. - How long should I wait before filing a report?
A: File the report as soon as possible while the details are fresh in your mind. We recommend within the hour or no more than 12 to 24 hours later. Memories begin to fade quickly. - What will happen to my report after I submit it?
A: Your report will be read by SRW representatives who will attempt to assess its validity. Whether the report is related to a reentry or not, SRW representatives will provide an email feedback as soon as a decision has been reached. This might be quickly with additional information requests especially if it can be immediately tied to a reentry. If there have been many reports it could be several days or more. If your report cannot be connected with an event, we may recommend you contact another body such as the International Meteor Organization. - What is a good way for me to better understand directions at night?
A: Carry a compass or GPS unit or smart phone that has a compass feature. The best way is to learn the constellations so you can more easily identify North, South, East and West. - What equipment do I need in order to make useful observations or reports of a reentry?
A: You do not need a telescope. A pair of binoculars may be of some use, however. A voice recorder and time signal received would be very helpful in linking details of the reentry to absolute time. Your eyes, if they are 20-20 with glasses/contacts or normal vision make the best ‘sensors’. It helps to have other, younger observers with you who have confirmed good vision. Please determine ahead of time if you or others suffer from color blindness, near-sightedness or other vision ailment so this may be reported. A static 35mm or video camera is also good for documentation. - Can a photograph be of use in place of video for a reentry?
A: Yes, provided certain conditions are met. The photographer must have some prior knowledge that a reentry may happen near his vantage point. Then he or she can arrange to set up a 35mm digital camera on a stable tripod with a shutter release. The ISO should be set to 1600 or higher and the camera placed far from lights. The exposure should be pre-set to ‘bulb’. The photographer, knowing what direction to look based on the reentry prediction should use a wide angle lens -e.g. 14mm- on the camera. When the reentering satellite is seen and understood to be real, the photographer leads the reentry so the field of view is placed just ahead of the flight path. Just before the reentry passes through the field of view, the shutter release should be activated. The reentry will then cross and exit the field of view. Then the shutter is closed. If there is time a second photo may be taken in the same manner. It would help if the internal camera clock has been accurately set to the local date, hour and minute. This information can then be retrieved after the photo is downloaded. It is important to document the direction in which the camera was pointed, but if the exposure is long enough and the sky is devoid of cloud, stars will embed themselves in the image and the flight path may be recognized against the star background. Video is more useful since it grabs a frame each .033 seconds but if the sensitivity of the video is not good, only the brighter pieces may be captured. - How do I know that either my 35mm camera will work or my video camera will be effect give in documenting a reentry?
A: Practice pointing both at bright stars. For the video camera see if you can manually open up the lens as far as possible to determine the level of minimal star brightness that can be clearly recorded. For the 35mm camera, take 15 or 30 second test exposures of the sky and see the level of brightness of stars that can or cannot be recorded. You must never take such a camera to a reentry without first having tested it, charged batteries fully, or focused it on stars prior to the reentry? - What are the most important things to think about in photography or video of a reentry?
A: Proper focus is the most important thing to verify before the reentry session. Testing the camera by pretending/simulating a reentry many days before will help ensure good documentation. Avoid hand holding a video camera. Mount on a secure tripod and on a stable surface that will not give way during the reentry just as you must do with a 35mm camera. Point and shoot cameras are not to be used. - Should I be using the zoom feature on my video camera?
A: Probably not. But test it on a moving airplane at night and see if the image remains in focus. Zooming in and out consumes battery power and may result in a field of view that is too small to contain reference objects such as bright stars or buildings which are necessary to help in the post reentry analysis. - Why are you not able to process UFO reports?
A: Such reports take too much time and resources to investigate. SRW personnel are volunteers who have limited time and resources. - If I have seen a meteor, fireball or UFO, should I send you this sighting?
A: No, we are not interested in such events. Meteor/Fireball observations can be sent to http://www.imo.net/ or http://www.amsmeteors.org/ , while UFO sighting can be sent to http://www.nuforc.org/ or http://www.mufon.com/ .
SRW Identified Reentries
Below is a table for some satellite reentry events which were identified or followed up by SRW program.
| Date | Time (UT) | Country | Satellite Name | NORAD # | Map | Videos or Photos |
|---|---|---|---|---|---|---|
| 02 October 2016 | 18:43 | Wiltshire, United Kingdom | FLOCK 2B 2 | 40951 | Location Map | Report and Videos |
| 26 September 2016 | 02:26 | Madura Island, East Java, Indonesia | JCSAT 16 FALCON 9 R/B | 41730 | Location Map | Report and Photos |
| 30 January 2016 | 12:01 | Hawaii, USA | CZ-3B R/B | 40893 | Location Map | Report |
| 15 January 2016 | 05:51 | Colombia and Chile | CZ-3B R/B | 40983 | Location Map | Videos |
| 03 January 2016 | 18:41 | Kiev, Ukraine | SL-8 DEB | 16866 | Location Map | Video |
| 23 December 2015 | 02:08 | California and Nevada – USA | PROGRESS 62P R/B | 41178 | Location Map | Report and Videos |
| 04 November 2015 | 09:58 | WI, MI, MN – USA | NFIRE | 31140 | Location Map | Report |
| 08 October 2015 | 15:41 | Yemen, Oman, Saudi, Iran | ATLAS 5 CENTAUR R/B Fuel Dump / Manoeuvring Burns not reentry |
40978 | Location Map | Video |
| 31 August 2015 | 09:03 | Hawaii, USA | COSMOS 1315 | 12903 | Location Map | Video |
| 25 July 2015 | 06:01 | Windward Islands, French Polynesia | SOYUZ-TMA 17M R/B | 40745 | Location Map | Video |
| 24 February 2015 | 05:54 | Montana, Idaho, Utah – USA | YOAGAN 26 CZ-4B R/B | 40363 | Location Map | Video |
| 17 January 2015 | 21:48 | East Amur, Russia | DRAGON CRS-5 DEB Probably Falcon 9 2nd Stage (15001B / 40371) |
40373 | Location Map | Video , More |
| 28 December 2014 | 04:40 | Brazil | Falcon 9 R/B | 40142 | Location Map | Video |
| 26 November 2014 | 03:39 | Hungary | SL-4 R/B | 40313 | Location Map | Video , More |
| 23 November 2014 | 01:36 | Saudi | SAR LUPE 4 SL-8 R/B | 32751 | Location Map | Newspaper Report |
| 20 October 2014 | 21:30 | Brazil | Intelsat 601 Ariane 44L R/B | 21766 | Location Map | Video |
| 16 February 2014 | 01:40 | Saudi | Cosmos 1220 | 12054 | Location Map | Video |
| 16 January 2014 | 20:07 | Saudi | Chinasat9 RB (CZ-3B R/B) | 33052 | Location Map | Video |