Identifying Satellite Launch Origins with Historical Examples

Identifying Satellite Launch Origins
with Historical Examples
Michael E. Stringer∗
Bob Teets∍
Robin Thurstonξ
The 1st Command and Control Squadron’s (1 CACS) mission is
to maintain the most accurate satellite catalog of Earth orbiting objects.
In order for 1 CACS to catalog an object in the space catalog the launch
origins of the satellite must be known. If a satellite is launched and
there is just one active payload on the launch vehicle and a simple
rocket body, then determining which is the payload and which is the
rocket body can be easy. However, when a new object is tracked and
does not immediately correlate to a known launch, a new analyst
satellite is created. An analyst satellite is an object that has not yet
been cataloged. The launch origin may not be known and therefore no
international designator is assigned. An analyst satellite may be
tracked and lost or tracked for months to years before its origin is
determined-if ever. When an analyst satellite is lost, the historical
element sets (elsets) are kept on file for future correlation efforts. This
paper will describe the tools and techniques that 1 CACS uses to
identify a satellite’s origin so that the object can be cataloged.
INTRODUCTION
The 1st Command and Control Squadron (1 CACS) has the mission to maintain the
most accurate and current satellite catalog as possible. 1 CACS was established in 1989
and shortly thereafter the analysts realized that the mission system was slow to upgrade
and the mission support system called Correlation, Analysis and Verification of
Ephemerides Network (CAVENet) was created. This system allows the analysts to plot
the historical trends of satellite element sets (elsets) very quickly and easily. This ability
to plot historical elsets allows the analysts to be able to rapidly verify that a new elset
correlates with the trend of the object in question and is therefore correct. The tools and
databases used by 1 CACS are described by Stringer1. These tools and databases allow 1
CACS to be able to correlate historical elset data back to the launch so that an analyst
satellite or group of analyst satellites, whose launch origins are unknown, can be
identified and cataloged. A few examples will be covered that will show long lost
objects, breakups, and cross-tags. These examples will show how 1 CACS can identify
and fix problems in the satellite catalog (SATCAT).
CORRELATING OBJECTS
The process of correlating objects starts with searching the catalog file for any
satellites that may match the object of interest. Candidate objects for correlation can be
∗
Chief Analyst, 1 CACS/DOUA, Space Analysis Center
Sencom Contractor, Retired Capt USAF 1CACS
ξ
Historical Analyst, 1 CACS/DOUA, Space Analysis Center, Retired Master Sergeant, USAF 1 CACS
∍
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found by using the scat program and searching for specific parameters that the analyst is
trying to match. Another method would be to use the UNIX grep command to search the
catalog files for possible matches. Once possible matches are found the objects can be
plotted together for the analyst to verify that the objects correlate. The first parameters
checked are usually the right ascension of the ascending node and inclination. If any
objects match in inclination and trend the same in node then the objects are in the same
plane as the object of interest. The next parameter checked is period to see if any objects
trend in period with the object of interest. The next parameter to check is the eccentricity
which will indicate if the candidate objects’ orbital shape match the object of interest.
The final step is to verify with any other parameters to confirm that a match or matches
have been found.
The above process is complete for all near earth object (periods less then 225
minutes) and most deep space objects. However, for near synchronous objects the
analyst may start with mean longitude to check for objects that are at the longitude of
interest. GOBS1 can also be used to find objects that match the parameters of plane,
relative energy, and longitude. Then the analyst can plot the candidate objects and check
the synch plot options to see how well the objects match. The analysts can then look at
the longitude plot, longitude drift rate plot, and the relative energy plots individually for a
more detailed analysis.
CORRELATING UCTS
The process for correlating UnCorrelated Tracks (UCTs) is similar to that
described above except the UCT files are separated by inclination and year. Therefore if
an analyst wanted to search for UCTs on an object with an inclination of 7.0 degrees and
wanted to look for possible matches in 1999 then the analyst would plot the file 9900799
with the object of interest. The UCT files are setup where the first two digits 99 represent
that these are UCTs and the next three digits are for the inclination of the UCTs and the
last two digits are for the year of the data.
The analyst can also plot the UCT files with the candidate objects and the object of
interest. This allows the analyst to see all possible matches to the object of interest at the
same time and therefore, UCTs may fill in any gaps in data that are not filled in by the
candidate objects.
COBE DEBRIS EXAMPLE
The Cosmic Background Explorer (COBE) satellite was launched on 18, Nov
1989. In early 1993, debris pieces were noted to be originating from the COBE payload.
There was some question as to whether the satellite was breaking up and NASA was
notified. NASA reported that the health of the satellite as intact leading to a theory that
the thermal blanket on the satellite was “shedding”. To date 78 trackable debris pieces
have been “shed” from COBE. Figure 1 is a plot of 20322 (COBE) and eight of the 78
pieces of “shed” thermal blanket.
Figure 2 is a plot of period only and enlarged in so the epochs are from 1993 to
1996. An analyst can see the different pieces coming off of the payload and by looking at
this parameter as well as others the analyst can keep the pieces from getting cross tagged.
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It is fairly easy to tell these eight apart however it can be very difficult to keep the pieces
from becoming cross-tagged when there are 78 pieces or in other breakups where there
are hundreds of pieces. Currently all but three pieces of debris have decayed that were
associated with the COBE payload. Figure 3 shows COBE and the three pieces of debris
still in orbit. The first two pieces 20324 and 20328 are not thermal blanket pieces but are
initial deployment related pieces.
Figure 1 Default plot of COBE and eight of its debris pieces.
BREAKUP EXAMPLE
In the last few years CAVENet has been populated with historical observation data
and this observation data has many single track UCTs. These UCTs have been processed
into single-track elsets and stored in the UCT files as described earlier. These UCT files
have lead to the discovery of breakups that had previously gone undetected. Twelve
breakups have been discovered using the UCT files and are listed in Table1.
SATNO
01863
14423
14787
15165
19622
19920
International Desg
1965-108A
1983-105B
1984-023B
1984-081C
1988-098B
1989-027B
Common Name
OV2-3/TITAN 3C
ARIANE 1 R/B
ARIANE 1 R/B
ARIANE 3 R/B
ARIANE 2 R/B
ARIANE 2 R/B
3
Breakup Date
21 Dec 65
27 Feb 84
04 Jul 84
18 Sep 84
22 Dec 88
19 Apr 89
14607
21640
16528
14190
24881
22273
1983-127G
SL-12 R/B (AUX) 26 Jul 89
1991-054C
IUS R/B(1)
02 Aug 91
1986-010B
CZ-3 R/B
17 May 92
1983-072B
ATLAS 75E R/B
29 Jan 96
1997-036B
ATLAS 2AS CEN 23 Feb 98 ??
1992-088E
SL-12 R/B (AUX) 29 Feb 00
Table 1 Breakups discovered by historical UCT analysis.
Figure 2 Period plot of COBE and eight of its debris pieces.
Figure 4 shows objects 14423 and 14787 plotted with the UCT file 99008. The
UCT file 99008 was pieced together from the UCT files 9900884, 9900885, and
9900886. These files were analyzed and all the UCTs that matched the two breakups
were pulled out of their normal UCT files and the specific UCT file 99008 was created.
Figure 5 is a plot of right ascension of the ascending node for objects 14423 and 14787
with UCTs 99008. Where the UCTs converge on the main satno’s plot is where the
breakup occurred.
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Figure 3 Plot of COBE and the three debris pieces from it, still in orbit.
Figure 4 Breakup plot for objects 14423 and 14787.
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Figure 5 Right ascension plot for the breakup of 14423 and 14787.
LONG LOST DELETED EXAMPLE
The Syncom 3 rocket body was cataloged but lost immediately after the launch.
Sometime after losing the rocket body the object was deleted in an effort to reduce the
lost list for long lost objects that were thought to be unrecoverable, this practice is no
longer used. However with the CAVENet system and the historical elsets the Syncom 3
rocket body was recovered.
Figure 6 shows that the rocket body was tracked as twelve different analyst
satellites (analsats) and also as UCTs. In 1993 analsat 88540 was matched with 81087.
This produced a history that went back to 1989. This history was then matched back to
88743 and 88249, which gave a history from 1988 to 1993. This extended history was
then searched back to find 56167, 87783, and 87423, which pushed the history back to
1986. A very short analsat history, 80005 was then matched and a few UCTs were
matched from 1984. Analsat 83766 was then matched to take the history back to 1980.
With more searching the final analsats, 83606 and 83550 were matched taking the history
back to 1971. No further matches could be found at this time.
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Figure 6 Plot of the analsats that form the Syncom 3 R/B history.
The next step was to figure out what this object was that kept getting tracked but
was not cataloged or had not been correlated to a launch. The databases were searched
for candidates that were not tracked or other objects that might have similar orbits to this
object. Once candidates were found the analyst would plot these objects together to see if
they were a match or were related. Since the object had no further matches, the analyst
looked for related objects and found that this unknown object matched the Syncom 3
launch. The analyst also noted that the rocket body from the Syncom 3 launch had been
cataloged but was then deleted and that this object must be the deleted rocket body. The
Space Surveillance Network (SSN) was tasked to collect signature data on the object and
it was confirmed as a rocket body.
MIS-CATALOGED OBJECTS
Occasionally objects get mis-cataloged from the beginning. The following is an
example of one of these mis-catalogs and how it was found and fixed. Figure 7 shows
the plot of 02353, which has an international designator (IDES) of 1965-109 (TRANSIT
10), and six other objects from the TRANSIT 10 launch. The plot shows that 02353 does
not match the rest of the objects from the launch in right ascension of the ascending node
(RANODE). This indicates that 02353 is incorrectly cataloged to the TRANSIT 10
launch. The parameters for the beginning of the history for object 02353 were searched
and the TRANSIT 12 launch (IDES 1966-024) was a possible match. Figure 8 shows
02353 plotted with the objects from the launch of (TRANSIT 12). Analyzing the
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RANODE plot and confirming with the other parameters, 02353 matches the launch of
TRANSIT 12. Object 02353’s common name and international designator were changed
to TRANSIT 12 DEB and 1966-024 respectively.
CROSS TAGGED OBJECTS
Objects get cross-tagged meaning that they are really the opposite tag of each
other. An example is YAMAL 101 (25896) and YAMAL 102 (25897). They originally
started off tagged correctly and then 27 days after launch, as both were drifting to their
synchronous locations, they were swapped. Figure 9 shows the history of these two
objects and shows that the objects were cross-tagged on 99276 day. Recently while
checking NASA’s Space Warn Bulletin an analyst noticed that YAMAL 101 was said to
be having problems and that YAMAL 102 was on station. Also a commercial
broadcasting web site that lists the locations of commercial satellites indicates that
YAMAL 102 is stationary at 90 degrees east. Looking back at the history showed that
the cross-tag occurred, so on 00249 the objects were swapped back to their proper tags.
YAMAL 101 is inoperative and did not stop at its planned location of 45 degree east and
YAMAL 102 is active and stationary at 90 degrees east.
Figure 7 Plot of 2353 with incorrect cataloged launch.
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Figure 8 Plot of 2353 with correct cataloged launch.
Figure 9 Cross tagged YAMAL 101 and YAMAL 102.
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SUMMARY
The historical data on the CAVENet system allows for identification of improperly
cataloged objects. The reasons for the errors are varied as demonstrated by the examples
used throughout the paper. The examples are by no means the only possible errors that
can be in the satellite catalog but are used to show the possible problems and the methods
for fixing these errors. Nearly 200 objects have been “recovered” to date. The term
“recovered” means that the object has been updated to be correctly cataloged, updated so
that the elset is current, or correctly decayed. The cumulative sum total of time that these
objects have been lost or mis-cataloged is over 2000 years. 1 CACS continues to analyze
this historical data to make the satellite catalog as accurate as possible. 1 CACS also
continues to develop methods to accurately catalog and maintain all objects from launch
until decay.
Stringer, M. E., Teets, R., Tools and Databases used to Maintain the Space Catalog at 1
CACS, Presented at the Fourth US/Russian Space Surveillance Workshop, US Naval
Observatory, Washington DC, Oct 23-27, 2000.
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