Subsystem #10
Reentry Vehicle
The Reentry Vehicle on the KH7 Gambit (206 was the unclassfied program name) vehicle was basically another small vehicle attached to the Gambit vehicle by bolts which were capable of being severed by a pyrotechnic when, near the end of the mission, the time came to return the film containing the imaging data acquired, to earth, for processing and distribution to the intelligence community. The severing of the bolts released the RV from the Orbital Control Vehicle (OCV), and some spring driven plungers pushed the RV away from the OCV, making it an autonomous vehicle on its own, with its mission to return the film to earth.
During mission operations, when points on the earth were imaged, the film moved through the camera system, and images were transferred to the film. The film was strung between two reels, a SUPPLY reel in the OCV near the camera and on a TAKEUP reel, which was in the RV, allowing film to be pulled through the camera system into the RV and wrapped around the take-up reel.
This continued until the end of the imaging data gathering mission, when it was time to return the film in the take-up reel in the RV to earth for processing. The separation of the RV required several activities to take place before the separation and recovery.
The Timeline below describes the various activities needed to recover the RV with film inside.
Commands were needed to power up the film take-up reel in the RV and the film supply reel in the OCV near the camera, to run any unused film into the RV for two reasons; one was to provide more weight (film) in bottom of the RV, to lower the center of gravity of the RV and aid in separation (to keep the bottom side of the RV, which was covered with ablative material, down as it approached the atmosphere where it could slowly burn off and slow the RV down as it was designed to do) and provide downward buoyancy for parachute activity. The second reason was to have the film all wrapped around the take-up reel before execution of another important command which needed to be executed.
A Cut and Seal secure command was required to release a spring -loaded knife-like chopping device which was at a slot in the top of the RV through which the film was pulled through and onto the take-up reel. The device severed the film if it had not already been moved onto the take-up reel. The prime function of the Cut and Seal execution was to imbed the chopping device into some material around the film entry point on the RV that made the RV watertight so the RV would not sink if it wound up in the ocean, to allow frogmen from surface vessels or helicopters to retrieve the RV, if necessary, before it sank.
The revolution on which recovery would be commanded was one of the first items set, along with the tracking stations required to be scheduled and used to load and execute commands in support of recovery. This was scheduled during preflight mission activities, once the orbit demanded for the mission was set by studies driven by input from members of the intelligence community. More on that later in a section on preflight tasks.
One interesting item to be dealt with on recovery day was, unfortunately, weather. I recall that recovery day briefings started early in the morning, when someone from the Weather group in the STC reported the weather status in the planned recovery zone. I also heard that airplanes scouted the recovery zone weather. I believe that military and civilian weather observation assets also aided in the weather status. If weather was bad (cloudy or raining) in the recovery area, pilots assigned to find and catch the RV would probably not be able to see the orange chute descending with the RV attached to it as well as hoped.
Mentioning civilian weather observation assets brings up another subject. I recall that a warning was given to civilian airlines to not fly through the recovery zone, likely denoting start and stop times, along with the area, which was probably the 60 by 1000 mile area described by figure SEARCHZONES. A few years ago, a military organization mistakenly shot down a civilian airliner in a war zone in the Mid East. One wonders if the civilian airliner was privy to a similar warning?
I believe that the weather assessment probably assessed weather status in more than the planned recovery area; if weather was found to be better above or below the planned recovery zones, then the recovery might be moved, which caused a look at extra things such as could any surface vessels needing to be in the recovery area make it to the new zone, and would it be possible to have tracking stations available to support the new location. Moving the zones higher north or lower south would mean a new deboost time, and would all RTS’s be available for use, most notably Kodi where the deboost would occur?
One consideration was to MOVE the recovery to the next day, but the first thing asked then was whether the expendables (Stabilization Subsystem Freon Gas and battery capacity) would support another day on orbit or would the gas or battery power be exhausted and the vehicle be tumbling, out of control if the freon control gas was used up the next day, before it reached the recovery area? Normally, if that kind of mission expendables were still available it is likely that another day of gathering mission imaging data would have been done before recovering the RV; that is what the mission was all about.
Prior to recovery, the OCV and RV needed to be yawed to a reverse position and pitched down about 56 degrees (i. e., yawed 180 degrees from their normal nose forward attitude during mission operations), with the nose of the vehicle and the RV then being in a nose backward attitude, and pitched down (basically, pointing at the North Pole), the vehicle attitude NEEDED to accomplish separation and reentry, nominally planned to occur within the contact cone of the the Kodi tracking station on the recovery rev. See Figure YAWPDOWN, just below, for reasons for this attitude, which involves reducing satellite velocity slightly but just enough to allow the RV to leave the satellite orbit and head to a lower orbit, where it would reenter the atmosphere. So, the mission profile contained a Yaw Reverse and Pitch Down, meaning a command message to accomplish those vehicle attitude changes was needed to be loaded and executed prior to the RV separate commands.
Figure YAWPDOWN
-----------O> Vehicle velocity at start of yaw/pitch
<O---------- Vehicle yawed 180 degrees but velocity still same
magnitude and direction
<O …/ Vehicle pitched nose down 56 degrees from horizontal pointing backward
Degrees /
pitched / When retro rocket fired after
down / separation, the velocity components
with / for the RV are down and backwards
RV / from OCV velocity vector, as a
on / function of the 56 degree pitch-down
bottom / angle. The resulting velocity vector
\/ with down and backward components
subtracts from the large velocity vector still effective to the right and is enough to cause the RV to lose enough of its velocity to drop out of orbit and head back to earth.
The deboost of the RV required an orbit planning run on one of the large CDC 3xxx computers to generate a point on the earth to aim for, and a time to issue a retro fire command to the RV to bring the RV to that point on the recovery revolution. For all missions, I recall that the standard area of deboost was in the Pacific Ocean, north of Hawaii, and for this discussion, let us assume that the planned point was at 24 degrees north latitude on the ground trace for the vehicle at that point. For many years, I wondered why the recovery zones started at, for this discussion, 25 North Latitude and not allowing for the zones to start above the (for this discussion) 25 North Latitude point.
One day, around 1990, a coworker enlightened me by mentioning that it was because the RV was on a “minimum energy trajectory” and could not “come short”. The co-worker had worked the Corona program, which, I believe, used the same RV. So, if that is true, it is never too late to learn. Perhaps some orbital dynamics specialist will confirm that was the reason for only being able to overshoot the point and “go long”, if they have an opportunity to read this discussion and enlighten me.
A typical reentry corridor footprint on the ocean for the recovery was a rectangle, 60 miles wide and 1000 miles long, as shown in Figure SEARCHZONE, just below, where five recovery aircraft were stationed, waiting arrival of the RV from space. Oil Cake 1 aircraft coverage area started at 24 North latitude (for this discussion) and extended 200 miles south, where Oil Cake 2 picked up the search activity 200 miles south of 24 North for 200 miles south, and so on for the other three planes. NOTE: I have seen conflicting numbers for the distance each was from the next plane. Some documentation showed the planes 200 miles apart and other documentation showed the planes 100 miles apart. Perhaps someone, maybe one of the 6593rd Test Squadron from Hickham Air Force Basse, Hawaii, Oilcake pilots or someone from the RCC (Recovery Control Center) at Hickham AFB, Hawaii can say which is correct, if they happen to have access to this writeup.
FIGURE SEARCHEVENTS Event # Reported Function 12 No sighting 18 Beacon acquired – Bearing ____ 19 Sighted | 14 Lost sighting 21 Lost in clouds 16 Lining up for looksee pass 17 Chute damaged 12 Hardware damaged | 27 Missed 32 In trail 11 Aboard plane 20 In water
FIGURE SEARCHZONES ---------------^------ 60 miles wide ---------- 200 miles south ---------- 400 miles south ----------600 miles south ----------800 miles south --------1000 miles south
NOTE: Figure SEARCHEVENTS, just above, is a sample of a “cheat sheet” used when reporting of various events by the Oilcake pilots in the recovery zone. This voice report (such as “Oilcake 1, event 19”) was routed to the RCC at Hickham Air Force Base in Hawaii, to SCF tracking stations monitoring the recovery and the STC in Sunnyvale, California, providing a running commentary on the search efforts. A page similar to this sample of an event reporting sheet (some events to report may be missing but the list presented is my best recollection many years after using them) was in the classified program part of an Orbital Requirements Document, available for use any time, but copies similar to the sample page usually appeared pinned to a wall or white board in various closed areas on recovery day, so there was no need to make a copy. The event numbers changed for each mission, so a happy report of an event number for one recovery may not report good news for the next recovery, should some rogue monitor the recovery activity and try to deduce results.
I assumed that all the recovery activity traffic on the nets were of secure nature, but many years after working the program, I was told by someone that a person working the program at Vandenberg AFB was a ham radio operator. On recovery day, on his way home, he would look at the event list and (for this example) when home, he would monitor activity for a report of “Oilcake _ , Event 11” by his shortwave rig, and would have known that the recovery for the mission documented herein was successful! I was kind of surprised that it was that easy to monitor activity.
I recall hearing that in the recovery zone during recovery activity, the pilots were subject to some protocols and rules that they had to follow, The rule for lineup of planes down the recovery 60 by 200 mile footprint dictated that the plane in Oilcake 1 position was the plane that had gone the longest WITHOUT catching an RV, and the Oilcake 5 position was filled by the plane that had gone the shortest time WITHOUT catching an RV.
If a plane reported the first sighting of the orange recovery chute they had the first chance to attempt capture, but if they lost sight of it, they went to the end of the line; this would have discouraged crews from premature reporting. A miss (no snag) also sent the plane to the end of the line. I also was told that any Oilcake crew capturing the RV was rewarded with a 3 day pass into Honolulu. If any of the Oilcake pilots reads this, and can do so, please feel free to enlighten the rest of us with the recovery day rules as you remember them.
Regarding the monitoring of activity on recovery day, one interesting introduction into the recovery activities was the presence of fishing trawlers and, perhaps, instrumentation ships of another nation in the recovery zone. The presence of these in or near the recovery area was interesting, particularly in view of the fact that similar trawlers also were sometimes near the 1200 (later 2400) bit data lines sending telemetry data from tracking stations to the STC for reporting during a contact.
On occasion, apparently in an attempt to repair some fishing lines or nets, the 1200 bit data line from an RTS tracking stations were “accidentally” severed; one time I heard that the line was severed in more than one place, perhaps 5 times. The speculation was that if a line were cut and spliced back together, measuring line characteristics such as impedance would find it different than what is was before a cut and splice. This was thought to be useful in masking adding a tap in the line to monitor traffic on that line in some manner, perhaps to a trawler for transmission on to some other station. The line most affected, as I recall, was the line from Pogo to the US, which was a key station for supporting activities. Just cutting a line and not splicing it back together could also cause loss of use of that for a station contact, a not good situation if it were needed, for example, for an upcoming recovery pass.
Activities in international waters were always a little more tension causing, as I recall. I still wonder what would have happened if an RV was not caught and wound up in the ocean, with frogmen or surface vessels of another nation closing in on the RV in the water. Would action have been taken by friendly forces to, as an example, sink the RV somehow? Risky at best, but one might ask if the Oilcake planes had procedures covering what action they might take? The same question might be asked of any surface vessels or choppers supporting the recovery.
I recall hearing that after liftoff of the Gambit vehicle, with a plan to perform a day or more of mission imaging operations and recover the RV on a nominal recovery revolution (18, 34, 50 and so on), a strange event occurred. It seems that, post launch, after a few revolutions had taken place, when interested parties could monitor the progress of the vehicle on orbit, track the vehicle and compute the orbit of the vehicle, a trawler, instrumentation ship or other surface vessel of another nation was stationed under the ground trace, on the planned recovery revolution perhaps hoping to have an opportunity to retrieve the RV! I wondered how the country knew where to send their “monitor” ship, but recalled that the prelaunch rehearsals performed before launch probably went through simulated recovery on the planned revolution, which, if monitored, might have given the info needed to position a ship in the proper location.
Someone recalled that another similar thing occurred, albeit slightly different. After having a few missions performing recovery operations on a nominal recovery, and seeing vessels of another nation in the correct recovery area on these missions, when the plan for the next mission was to perform more mission days and recover at a later recovery revolution, the sentiment was that they’ll have their vessels in the wrong area! Wrong -- the vessels were in the correct new recovery position, indicating they were likely monitoring rehearsals, and/or perhaps utilizing a tap on the 1200 bit data line that they had connected to, as mentioned another place in these recollections.
Also of note is the fact that, at least one time, some kind of vessel of another nation found itself beached near, I think, Point Mugu, south of the Vandenberg AFB launch area. I recall hearing that they turned down an offer of help getting off the rocks that was made by the US, saying they would wait for one if their salvage/maintenance vessels to arrive and free them from their predicament. This took a while for the vessel to arrive, coming from a long ways, during which time several launches from VAFB were performed with the beached vessel close enough to be able to record goings on, if they had the capability and inclination to do so! I doubt that there was much consideration given to holding launches until the vessel was freed and left the area. Any delay in one launch would likely have a domino effect to launches scheduled later, with launch pads, boosters and related tasks vying for resources.
In the general case, the recovery revs planned and used started at rev 18 (allowing one day of mission imaging data operations) and every sixteen revs thereafter, i. e., rev 34, 50, 66, 84, 100, 116 and so on when more than one day of mission imaging operations were planned. Selection of tracking stations on these revolutions were scheduled and used to obtain telemetry and tracking data for use and also provided commanding capability in support of RV recovery. The vehicle orbit placed the vehicle passing these three tracking stations to be in their cones of access, namely Pogo, Kodi and Hula, with the separation of the RV generally occurring in the Kodi tracking station acquisition cone of observation to allow people to monitor progress of the operation.
These stations normally were in the acquisition cone for each of the stations for a good recovery rev, going south to north, first encountering the Pogo tracking station, then proceeding north towards the North Pole, then crossing over the north pole area, heading south towards the South Pole, past the Kodi tracking station on the recovery rev, and then past the Hula tracking station after the RV separation which should have occurred at Kodi.
I believe that the yaw reverse may have been commanded in the Pogo station cone area and the pitch down may have been commanded early in the Kodi station cone area, in order to be sure that vehicle attitude was correct before executing the four commands needed to separate the RV from the OCV, as will be seen in the upcoming timeline of RV deboost activities.
During the 37 missions of the G vehicle, I worked on shift in two areas. From the first launch on 12 July 1963 until 1 July 1965, my shift support was in the vehicle TA (Technical Advisor) area, where I supported vehicle hardware. From 1 July 1965 until the end of the program in 1967, I worked shift in the Command Generation group, where my job was to generate command messages to be sent to and executed by the OCV Command Subsystem to control the OCV for whatever the mission profile had scheduled. Two things scheduled were to acquire mission imaging data and get this data back to earth. There were other activities scheduled on the mission profile, but for this discussion of the RV, I will focus on RV deboost activities. More on the mission and other activities in a later section discussing mission activities.
After seeing both the hardware and mission side of the operation, I have always felt that recovery day was sort of a Judgment day, as MANY things could occur on that day to preclude having a successful end to the mission, namely, the inability to successfully return the RV and film data in it to earth. What follows is a treatise on things going on recovery day and where possible problems could deny a successful RV deboost.
RV DEBOOST TIMELINE Function Activity resulting from Function Commands RV film take-up and supply reel power From OCV up to move all film to take-up reel in RV. Commands Cut and Seal film at film entry point From OCV to RV. Commands Yaw Reverse From OCV Commands Pitch Down approximately 56 degrees From OCV Commands 4 from OCV Command Subsystem From OCV (Prearm, Arm, Transfer, and Separate), then Rocket, Separation, and Recovery Programmers in the RV executed more functions necessary to complete RV deboost toward the ocean and waiting recovery aircraft. Prearm Activate RV telemetry battery, Delta 4 on OCV power bus. Arm Turn Recovery Beacon on, start Inhibit Timer enabling two 3G sensing functions, arm Thermal Relay Module, Delta 4 on telemetry battery, arm Recovery Programmer. Transfer Energize Thermal batteries, backup recovery beacon on, 0.9 seconds delay then InFlight Disconnect (IFD) blown loose from OCV which starts Rocket Programmer giving Retro 13.8 seconds after Transfer/ICD blown when electrical ground is lifted. Separate Separate RV from OCV, pushoff/tipoff via springs when explosive bolts activate and springs push RV away from OCV. RV was then free of the OCV and the rest of sequence was via Separation, Rocket and Recovery Programmers as described below. Sequence by Rocket Programmer Spin Stabilize RV by spinning it around centerline of RV, as it heads toward atmosphere, and just before Retro rocket onThrust Cone fires and sends RV on its’ way back to earth. This spin is similar to that of a rifle spinning a bullet because of riflimg in its barrel, which sends the bullet towards its target more accurately. Retro Rocket on top of Thrust Cone fires to start downward flight, which occurs 13.8 seconds after Transfer. RV is in random orientation starting in a zero g environment as it leaves area of OCV, and should orient itself to a stable condition with the RV heat shield at bottom as it starts to encounter gravity due to center of gravity being low in RV by design/planning.
A prelaunch spin/balance procedure (very similar to having a wheel balance on an automoble) assured orientation by adding weight (weights taped strategically) to bottom of RV, well taped to assure that weights do not float around in space, encounter an electrical connection, and create a fire or short in vehicle. More weight added before recovery by film takeup reel with film wrapped on it during mission adds more weight near bottom of RV.
As RV approaches atmosphere, recorder turnon records data through blackout period at sensing of first 3G entry from 0 to 3 Gs – near 0 Gs as recovery starts and 3 Gs as RV starts encountering drag created on route through atmosphere toward recovery planes. Recorded data automatically played back later. See FIGURE 3G
FIGURE 3 G
Time increasing >>>>>
0 G \ A
1 G \ E / 1 G
2 G \__________ /
3 G \ B D / 3 G
\ /
\ / NOTE: 9 G value max
\ / loading figure is from
\ / program documentation,
\ / but could be smaller or
9 G \/ larger number.
C
0 G on top left @ A
3G @ B to 9G @ C
9 G @ C Max expected, then through 3 G toward 1 G at plane capture
3 G @ D
1 G @ E
Curve below B and D shows blackout/ionization time and G forces as RV enters blackout when extreme friction causes kinetic energy from capsule speed to be dissipated as heat energy (conservation of energy principle?) as the RV slows down through about 9 Gs and then transitions back through 3G towards a 1 G environment on Earth.
The blackout is caused by the heat burning off the ablative material on the bottom of the RV, which is by design. As the material slowly burns, flames from this action surround the RV and heat and flame prevents any signal from being received. When the vehicle slows down and the flame is gone, the RV beacon signal will again be heard. This time of blackout is the time around maximum G loading/pressure on the RV.
Shortly after entering 3G and higher Gs , it is at this time that the RV enters a blackout period as heating up of the ablative shield will be going on, with, eventually, the RV surrounded by a cone of fire from the shield ablation. Loss of all contact with the RV ensues, until the vehicle is slowed down enough to have survived the reentry environment enroute to the waiting aircraft. This time is, I believe, a time of maximum jeopardy on the vehicle environment, as it goes through the atmosphere via a rough reentry profile.
Sequence from Recovery Programmer
Normally after 2nd 3G switch closure occurs, which indicates RV probably survived the harsh reentry environment, fire and all!
NOTE: Should the 2nd 3G switch closure not be sensed within 860 seconds, several things could have happened, none of which would be good news! The RV may not have survived the strong reentry environment and been destroyed enroute to the sea. I have been told that if the RV was pointing improperly at retto-fire time, it could encounter the start of the atmosphere at such an angle that could cause it to kind of bounce off the atmosphere and wind up in a higher orbit, precluding its recovery and leaving the vehicle to be monitored by debris monitoring agencies for as long as it might be until its’ orbit decayed enough to reenter the atmosphere and burn up. At separation time, if the RV was oriented at an angle pointing away from the earth, retro firing could cause the RV being launched in to a HIGHER orbit, similar to skipping off the top of the atmosphere.
If none of these malfunctions had happened, the RV had survived the reentry, and the Separation Progammer did not sense a 2nd 3G closure, after 860 seconds, the Separation Programmer would have ejected the Thrust Cone, which pulled the parachute cover off, severed the parachute lines attached to the RV, and ejected the ablative heat shield from the bottom of the RV. This disabling would mean that when the hardware did decay from orbit (which could be a long time until it happened if it was in a much higher orbit), the RV would reenter the atmosphere without ablative shield protection, the parachute would likely burn up and the ablative shield would be on its’ way to destruction or ocean impact! Some pieces might survive reentry, and not necessarily at the same time, making it more difficult for monitors of space junk to keep track of. This disabling activity was aimed at disabling an RV from surviving reentry and hitting earth in some undesirable place on earth.
It should be noted that if an RV survived reentry successfully, and landed in the ocean by parachute, but no forces were aware of its’ location, after 40 -0/+32 hours, a salt water soluble sink plug would disintegrate and allow water to enter the RV and sink after 40 hours, but no later than 72 hours, thus denying anyone access to the RV and its’ classified data inside.
If 2d 3G switch closure occurs, Despin and activity defined just below occurs.
Despin Stops RV from spinning after entering
atmosphere to prevent chute lines
from tangling; also provides better direction finding on Recovery beacon that isn’t rotating.
Thrust
Cone
Eject Thrust Cone (with no longer needed Thrust Cone, spin/despin hardware, nitrogen spin gas bottle and other hardware) separated/ejected from RV, which pulls parachute cover off.
Drogue and deploys a Drogue chute to slow
Chute descent of RV and chutes. The ejection
Deploy of Thrust Cone and other hardware on Thrust Cone lessens the weight of the RV and decreases weight that parachutes must handle.
Main Main chute deployed in reefed condition,
Chute with Main chute lines being squeezed
Reefed together to allow some air in chute but not a deployed full chute opening
to prevent tearing chute lines from chute. Drogue chute was stronger than Main chute and designed to survive through strong deceleration forces after rapid reentry into atmosphere.
Main Main chute dereefed by cutting cord
Chute holding chute shroud lines together to
Dereefed prevent total Main Chute from opening
earlier. See Figure REEFED.
FIGURE REEFED <<<< Dereefed <<<< Reefed
Shroud lines tied (reefed) to gather all lines and cord tie was cut loose at de-reef time to enable normal chute usage for planes to snag and reel RV and chute into plane.
RV
With the RV and Chutes on their way to ocean, into a 1 G environment, the recovery planes were in position to locate and snag the chutes. To aid in this endeavor, several location and recovery aids helped. A huge help was the Recovery Beacon, which the planes used Direction Finding (DF) hardware on to see if they could detect the direction from the plane to the RV package. A flashing light was also on the RV, and I believe that metal chaff was deployed by the RV for radars to search for, but this may not have been on all vehicles. The parachute was orange, to enhance visibility of it, too. Perhaps some of the “Oilcake” recovery plane pilots might enlighten us on the usefulness of these location aids, if any of them get a chance to read this.
If all went well, and the RV was descending into the recovery search area, then five recovery aircraft (designated as Oilcake 1 through Oilcake 5) from the Recovery Control Center at Hickham Air Force Base, Hawaii, were airborne to find and snag the parachute lines tied to the RV, and reel it aboard the aircraft.
On the chance that the RV was not seen and captured and wound up in the ocean, the flashing light on the RV would aid searchers, along with orange dye in the water. I believe that there were ships in the area, with frogmen aboard, prepared to go into the water and retrieve the RV package. That assumes the RV impacted in the water in a planned area.
Note that I said that frogmen and ships might be in the area for retrieval. Hopefully, they are friendly forces that can do the retrieval. HOWEVER, if the RV landed in the ocean, it is international waters, and as such, could be retrieved by any nation who happened to have surface vessels closer to the RV, including nations not friendly to the US.
The air capture of the RV by snagging its’ parachute was, hopefully, the successful end to the mission with snagging of the parachute attached to the RV by one of the Oilcake 1 through Oilcake 5 planes assigned to that job. The planes were aligned in a pattern as shown by Figure OCZONES as depicted previously.
Once the RV was pulled board the recovery plane, I was told that the recovery beacon was turned off using some kind of a wrench that all planes had. I recall hearing the whooping sound of the beacon on the net during recovery operations, probably as the plane approached the RV on its’ chute, or, perhaps from the plane after the chute ws reeled into the plane.
I was told that each plane had a wrench/key that allowed someone to turn off the noisy beacon. Apparently, during one recovery the turnoff hardware could not be found, so the plane flew somewhere with the beacon illuminating the airwaves, maybe all the way back to the US mainland.
Now let me delineate some of the potential problems that were worrisome if they were ever encountered. Looking at the timeline, if the film going into the RV and being wrapped on the take-up reel was not completed and the cut and seal activity did not complete, then the film, still attached to the film supply reel in the OCV, would impede the action of the Separation and Retro Rocket activity. The film would essentially be a lanyard holding back the Separation and Retro Rocket activity by acting as a lanyard holding the RV to the OCV, which would not have been a good situation!
Note that the Transfer command starts a 13.8 second timer which executes the Retro Rocket function, which would be catastrophic if the Separate command had not separated the RV from the OCV, The Retro firing would basically fire its rocket into the OCV, probably causing an explosion which could blow the OCV apart!
Related to that, I believe that on one recovery activity, normal separation and retro rocket activity ensued, but after that ALL contact, i. e., telemetry, tracking and command (TT&C) links with the OCV were lost. This lead to speculation that prior to retro fire time, the separation of the RV, which involved a spring loaded plunger to push the RV away from the OCV executed, but the pushoff of the RV was not a clean pushoff. The RV retro fire occurred with the RV not in its normal firing positioning angle, and the retro firing sent some debris into the OCV, perhaps disabling the TT&C components such that permanent non- contact with the vehicle was the result. I think I recall hearing that other space assets were able to skin track the OCV and reported it appeared to be sailing along in a normal belly down configuration, which would have been the case until one of the expendables (freon control gas or battery power) ran out.
It should be noted that the movement of plunger pushing the RV away from the OCV was sent to telemetry and the plunger rate and direction analyzed post flight to determine if the separation was clean. Another piece of telemetry data analyzed post flight was the pyrotechnic squib firings for the Separate command to track their performance. Telemetry channel 3-13 monitored total vehicle current (3-13 was a good add to the telemetry list and it was used for analysis quite often) and one could observe the current used to trigger the pyrotechnics, of which there were 2, a primary and a backup pyrotechnic. Postflight, I recall being asked to look at the total current value at squib firing time and compare it with the SAME value and time on a previous mission. The amplitude/value of the current was ½ of the prior mission, leading to the deduction that one of the squibs (primary or redundant) DID NOT fire. I assume that this anomaly was documented in a 30 day post flight report that all contractors completed.
There also was a post flight 5 day quick look report, whose primary function was to document, as soon as possible, anomalies that might need to have some hardware or software change made before the next launch, entailing perhaps a schedule slip for the next launch. More on the 5 and 30 day post flight reporting later.
I previously mentioned that after a successful catch of the RV by one of the Oilcake planes, that the RV was then flown East to the US, and the developed film images were delivered to analysts for their use. On one mission, as the film was removed from the RV, a TORQUE wrench was found wrapped up in the film! This find caused some repercussions, as the wrench in the film caused a bump of sorts in the roll of film, which could have jammed the take-up activity if the bump became large enough to cause the take-up reel from rotating any further during on orbit mission data gathering!
I heard that the torque wrench was returned to a higher level GE manager by a government employee, who directed that an investigation take place to see how the wrench got into the film roll! Additionally, I heard that the event caused loss of part of the incentive fee that contractors receive at completion of each mission.
Torque wrenches were employed when working on the vehicle, to prevent threads from being stripped when removing or replacing components on the RV, which was a VERY expensive vehicle. Any set of threads damaged might, as an example, preclude securing a component to its’ place as had been done before threads were stripped.
As an example, sometime before launch, the film supply used during ground test was likely replaced by a pristine roll, the take-up reel was probably checked for the proper alignment to assure correct take-up action, and then the cover of the RV was put on securely to assure that it was tightened down properly. Procedures in place to do this defined how much torque to apply (and none extra) to prevent damage.
I doubt that it was determined who used the torque wrench and left it in a position such that it got wound up in the film, unless employees had their own wrenches which could be traced. I do know that after this incident that all persons needing to work on the vehicle were required to go to a tool crib to check out a tool kit. An audit of tools in the toolkit ensued, the worker signed for the tool kit, used tools in it, and, on return of it to the tool crib, an audit was done in the tool kit to assure all tools in the kit at checkout time were in the kit at check-in time.
Another impact/change imposed by this event was in the area of the balancing of the RV, as mentioned earlier to force the center of gravity of the RV to be low in the RV, and on the spin axis of the RV. This procedure caused balancing weights to be added to the RV strategically as needed, then taped to the vehicle so they could not get loose, float around in space and cause electrical shorts or some other problem.
On prior missions and this mission, after taping the weights as needed, workmen sometimes wrote their name and other info on the tape, to be able to say their name had gone to space and returned. After this incident, I was recently told that NO ONE ever wrote on the tape while prepping the vehicle for launch! Of note is the fact that it was known that something was causing a disturbance in the take-up activity during the mission, before the END of the mission data gathering. A periodic disturbance on the frequency of rotation of the film take-up was noted on the Pitch Fine Rate telemetry point, and continuous channel 3-13 (total vehicle current) showed a spike as the film supply activity rotated, perhaps drawing extra current to move the bump past some area of stiction. This data was likely from a Cook RTS pass, when The full downlink was available to be transmitted to a ground station in the STC. Normally, the data available was only selected points processed by the Augmentation (“Augie”) data system.
Two commands executed during the RV recovery scenario mentioned previously are worth emphasizing again, since they require more effort in executing them. They are the film Cut and Seal command and the Separate command, both which require a match of a secure word pattern resident in the vehicle (from a secure plug with patterns needed) with a word in the uplinked command message. Another command also requires a secure word match at execution time, namely the Orbit Adjust Engine(s) on command. All three attained that status by being catastrophic commands which, if spuriously executed, would be catastrophic to the mission.
A spurious Cut and Seal command execution would cut the film at entry to the RV, causing loss of tension on the film, and this would mean the end of any imaging. Other engineering type flight objectives might be executed, but the prime mission would be over. The Separate command would separate the RV from the vehicle which would take away a means of returning any imaging data on the film. Commanding the Orbit Adjust engines on randomly, without an engines off command, would probably cause a long orbit adjust engine burn, likely raising the orbit some, but also depleting all of the OA engine fuel and oxidizer!
LIFEBOAT BACKUP
It should be noted that the Lifeboat Subsystem was a backup RV recovery system. See the Lifeboat subsystem writeup for details.
RV DRAWING RED/BLACK LINES
There were TWO versions of schematics for the RV subsystem, one being unclassified and one being classified. The unclassified version was missing classified wires, and when using the unclassified schematic in briefings, often a comment was made that “there should be more wires on this schematic, but they are black but red on the classified version”. This was spawned due to security reasons. I believe that, originally, the RVs were obtained from the GE Reentry Systems Department in downtown Philadelphia, then taken to the GE plant in Valley Forge, where, in a closed area, some mechanical retrofits took place, to adapt the RV for an imaging mission. A slot was cut in the top of the RV, to provide a way for the film to enter the RV, where it was threaded on a film takeup reel, with the reel and hardware brackets to hold the take-up reel being added, in addition to needed power cabling and telemetry sensors and their necessary cabling. At the slot area cut in the top of the RV where film entered the RV, a spring loaded knife/bayonet mechanism was added, along with some material bonded around the film slot. When the time came to deboost the RV, a Cut and Seal command was issued that severed the film (if all film had not already been rolled up on the film takeup reel) and the bayonet/knife was imbedded in the material around the film slot, making the RV watertight to prevent hte RV from sinking should it wind up in the ocean near the end of the recovery effort. The retrofit effort also added cabling to provide power to the takeup reels, and to provide a ommand interface to execuite the cut and seal command. The retrofits made the RV a classified piece of hardware, to be seen only in closed areas.
Go to Subsystem 11: Lifeboat.