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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
See http://www.fatemag.com/2005_11art1.html for the UFO view.
I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. |
#2
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Going Around, Coming Around: Returning Interplanetary 'SpaceDebris'
Jim Oberg wrote: See http://www.fatemag.com/2005_11art1.html for the UFO view. I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. The big problem with the reasoning of that article is the way they are estimating the size of objects based on their brightness- they see the object, then give a size estimate based on the average albedo range of asteroids. But it the object is a rocket stage the albedo is probably going to be far higher as it is probably white or silver in coloration (or in the case of some of the Soviet ones green or gray) and what you are looking at is a lot, lot, smaller than what you think it is. What you would want to do is examine the reflection spectrum of the object and determine what the surface you are seeing the sunlight reflected off of is made of....IIRC, didn't one of these mystery objects show that it was covered in titanium-based white paint when checked out in this way, and that pretty well nailed it down as a S-IVB stage from one of the Apollo flights? Pat |
#3
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
In message , Pat Flannery
writes Jim Oberg wrote: See http://www.fatemag.com/2005_11art1.html for the UFO view. I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. The big problem with the reasoning of that article is the way they are estimating the size of objects based on their brightness- they see the object, then give a size estimate based on the average albedo range of asteroids. But it the object is a rocket stage the albedo is probably going to be far higher as it is probably white or silver in coloration (or in the case of some of the Soviet ones green or gray) and what you are looking at is a lot, lot, smaller than what you think it is. What you would want to do is examine the reflection spectrum of the object and determine what the surface you are seeing the sunlight reflected off of is made of....IIRC, didn't one of these mystery objects show that it was covered in titanium-based white paint when checked out in this way, and that pretty well nailed it down as a S-IVB stage from one of the Apollo flights? Pat J002E3 is thought to be Apollo 12's S-IVB http://www.space.com/scienceastronomy/moon_impact_020916.html Isn't there a LM ascent stage in heliocentric orbit, too? |
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Going Around, Coming Around: Returning Interplanetary 'SpaceDebris'
Jonathan Silverlight wrote: J002E3 is thought to be Apollo 12's S-IVB http://www.space.com/scienceastronomy/moon_impact_020916.html Isn't there a LM ascent stage in heliocentric orbit, too? Apollo 10's "Snoopy" is in solar orbit. Pat |
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
That article mentions reactivating the old ALSEPS, in so far as I know
thats impossible |
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
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#7
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
"Jim Oberg" wrote in message
... See http://www.fatemag.com/2005_11art1.html for the UFO view. I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. My analysis of published brightness observations of 1991 VG reveals a standard magnitude of 6.3 (1000 km range, 90 deg phase angle), which is about 3 magnitudes fainter than expected of an S-IVB stage: http://satobs.org/seesat_ref/1991_VG/1991_VG.jpg If 1991 VG is space hardware of Earthly origin, then its standard magnitude is indicative of moderate size. For example, it is about as bright as the current generation of DMSP and NOAA LEO weather satellites, which are about 7 m long and 2 m in diameter. It is about 1 magnitude fainter than a typical Agena upper stage, which is about 6 m long and 1.5 m in diameter. The S-IVB stage is 18.7 m long and 6.6 m in diameter, which I estimate would have resulted in a standard magnitude of about 3. Skylab, a heavily modified S-IVB had an observed standard magnitude of about 1.7, but it was a good deal longer than a plain S-IVB, so std mag 3 seems about right for the latter. The SLA was 8.5 m high, 3.9 m dia at the top, and 6.6 m dia at the bottom. Each panel is 8.6 m long, and its cross-section is 2.8 m wide at the top and 4.7 m wide at the bottom. It seems too large to account for 1991 VG, but its shape is complex, so detailed modeling of its optical characteristics would be necessary to be certain. (Beyond my ability.) Ted Molczan |
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
Thanks for sharing these valuable insights on outerspacesights.
"Ted Molczan" wrote in message ... "Jim Oberg" wrote in message ... See http://www.fatemag.com/2005_11art1.html for the UFO view. I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. My analysis of published brightness observations of 1991 VG reveals a standard magnitude of 6.3 (1000 km range, 90 deg phase angle), which is about 3 magnitudes fainter than expected of an S-IVB stage: http://satobs.org/seesat_ref/1991_VG/1991_VG.jpg If 1991 VG is space hardware of Earthly origin, then its standard magnitude is indicative of moderate size. For example, it is about as bright as the current generation of DMSP and NOAA LEO weather satellites, which are about 7 m long and 2 m in diameter. It is about 1 magnitude fainter than a typical Agena upper stage, which is about 6 m long and 1.5 m in diameter. The S-IVB stage is 18.7 m long and 6.6 m in diameter, which I estimate would have resulted in a standard magnitude of about 3. Skylab, a heavily modified S-IVB had an observed standard magnitude of about 1.7, but it was a good deal longer than a plain S-IVB, so std mag 3 seems about right for the latter. The SLA was 8.5 m high, 3.9 m dia at the top, and 6.6 m dia at the bottom. Each panel is 8.6 m long, and its cross-section is 2.8 m wide at the top and 4.7 m wide at the bottom. It seems too large to account for 1991 VG, but its shape is complex, so detailed modeling of its optical characteristics would be necessary to be certain. (Beyond my ability.) Ted Molczan |
#9
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
"Ted Molczan" wrote in message
... "Jim Oberg" wrote in message ... See http://www.fatemag.com/2005_11art1.html for the UFO view. I personally favor SLA panels as the culprits, throwing in a significant 'solar sailing' to confuse the ballistic track-back calculations. My analysis of published brightness observations of 1991 VG reveals a standard magnitude of 6.3 (1000 km range, 90 deg phase angle), which is about 3 magnitudes fainter than expected of an S-IVB stage: http://satobs.org/seesat_ref/1991_VG/1991_VG.jpg If 1991 VG is space hardware of Earthly origin, then its standard magnitude is indicative of moderate size. For example, it is about as bright as the current generation of DMSP and NOAA LEO weather satellites, which are about 7 m long and 2 m in diameter. It is about 1 magnitude fainter than a typical Agena upper stage, which is about 6 m long and 1.5 m in diameter. The S-IVB stage is 18.7 m long and 6.6 m in diameter, which I estimate would have resulted in a standard magnitude of about 3. Skylab, a heavily modified S-IVB had an observed standard magnitude of about 1.7, but it was a good deal longer than a plain S-IVB, so std mag 3 seems about right for the latter. The SLA was 8.5 m high, 3.9 m dia at the top, and 6.6 m dia at the bottom. Each panel is 8.6 m long, and its cross-section is 2.8 m wide at the top and 4.7 m wide at the bottom. It seems too large to account for 1991 VG, but its shape is complex, so detailed modeling of its optical characteristics would be necessary to be certain. (Beyond my ability.) I should add that the above SLA cross-sections are its largest.Its smallest are about 0.6 m at the top and 1 m at the bottom. On average, its dimensions are about 8.6 m x 3.8 m x 0.8 m, which I estimate would result in a standard magnitude of about 5. This kind of estimate is accurate to within about 1 magnitude, so it is similar enough to 1991 VG to be interesting. As for the effect of SRP (solar radiation pressure), each SLA panel's mass is about 460 kg, resulting in an area to mass ratio of about 0.07 m^2/kg through the largest cross-section. The comparable value for an S-IVB stage is about 0.01 m^2/kg, so the SLA panels seem likely to be much more strongly affected by SRP than an S-IVB. I do not know whether or not the absolute difference in SRP would be sufficient for an SLA to account for 1991 VG's orbit. A more fundemental question: could any of the SLA panels have escaped their highly elliptical Earth orbit? Ted Molczan |
#10
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Going Around, Coming Around: Returning Interplanetary 'Space Debris'
"Ted Molczan" wrote:
A more fundemental question: could any of the SLA panels have escaped their highly elliptical Earth orbit? Good catch. I'd been thinking that the SLA panels would have behaved like the stage they came from - except the panels are released right after TLI, which for all flights mean a free return trajectory at that point. D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
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