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Jane’s Information Group, and a whole bunch of other sites, have “found” a new, large launch complex in Iran that is close to the rather spartan launch pad for the Safir. What is irksome (at least to me) is that the new launch complex is visible in Google Earth images dating back a year ago. This allows some interesting estimates for when the Simorgh project started, how much importance Iran assigns it, and when the new rocket might be launched (a lot sooner than some of us suspected). Here are two Google Earth images dating from 1 March 20010 2009 (typo!) and 9 October 2009. Nothing is visible at the site on 25 February 2005 so all this work is relatively recently. Iran is so active!

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One of the things that has always stuck in my mind from my childhood addition to science fiction was Robert Heinlein’s explanation of rocket guidance, where a special “cam” was machined to control the trajectory of a rocket every time it took off. The cam would be rotated with a constant speed and its radius at any given point would determine the average direction of the thrust. It turns out that exactly the same method is used in SCUD’s. (I’m not surprised, really. The reason I loved Heinlein’s books was the fact that he was a “hard core” science fiction writer who obviously calculated interplanetary trajectories to make sure his stories had the ring of truth in them.) In the case of the SCUD, a constant rate step motor turns an odd shaped cam that, in turn, adjusts a potentiometer. At that point, the potentiometer changes the average setting of the jet vanes that control the direction of the SCUD’s thrust. Of course, on top of this average motion, the guidance system—the various gyros and accelerometers—determine small displacements from the average in order to keep the wind and other disturbances from effecting the trajectory.

The SCUD is optimized for operating in the field and I can imagine that its Russian engineers first selected a mechanical “computer” for its ruggedness. However, it also might have had other advantages over more general purpose digital computers. It’s hard to imagine weight being one of those advantages given today’s computers but it might for a country just starting out designing a missile’s guidance system if you include all the adjunct equipment that would be needed such as digital-to-analog converts with enough power to control the jet vane actuators. Be that as it may, Iraq as late as 2002 was using an analog computer (electrical this time, not electro-mechanical as was the SCUD pitch controller) to control the pitch. This image of the Al Samoud II pitch “programmer” is from the UNMOVIC compendium:

I think this establishes, if it doesn’t quite explain why, a tendency for countries just starting out in developing their own missiles to use analog computers their guidance systems. Perhaps the reason is simply that analog computers are a logical next step from the systems—i.e. SCUDs—that they are used to. Of course, it doesn’t prove that a country, such as Iran, would use an analog computer but I find it suggestive. Let us, for the moment, assume that is the case. That might explain why Iranian documents suggest that the Safir uses radio guidance during its flight into orbit. Another possibility, one that I’m still working on, considers the impact of a long period of a pure gravity turn, where the average thrust is directly exactly opposite the vehicles velocity vector. (SCUDs and the Al Samoud II use a pitch program that approximates a pure gravity turn—after a substantial “kick” to get it moving in the right direction—by constantly changing the angle the thrust makes with the horizontal.) A trajectory based on a pure gravity turn appears to be very sensitive to the exact attitude of the missile when the “kick” is turned off. The long burn time associated with rockets like the Safir (which, according to some estimates, has a burn time of over 400 seconds) could allow those errors to accumulate and possibly prevent it from inserting its satellite into orbit. Ground-based radio guidance could provide an easy—and possibly quickly achieved—solution, especially if the Safir’s position is determined by GPS as was hinted at in the memos. That brings us back to the Safir and this image of a radio or radar dish displayed at the recent Space Days in Tehran:

This could be used for any number of signals associated with Safir (or, to be complete, it could have nothing to do with the Safir). It is, however, very unlikely to be associated with telemetry from the Omid satellites. That is, as I showed in an earlier post, handled by a different antenna. So this dish could be used simply for telemetry from the rocket during boost. Or also for sending back to the missile guidance commands. Unfortunately, we cannot see the attachment of the dish to the support column so we cannot determine if it can be slewed fast enough to follow the flight of the missile.

If it does follow the trajectory of the Safir, it does not need to be positioned very far down range to see the entire powered flight of the space launch. In fact, burnout of the Safir—which occurs about 920 km down range—is still visible at the launch pad with an elevation of 10 degrees. To complete the argument, there is an antenna mounted on the Safir airframe (and which all the photos of the Safir that I have seen have managed to minimize) that would suit this purpose very well. It is mounted over Fin I, which is aligned with the trajectory so that it is always pointed down toward the Earth during powered flight. This facilitates its visibility to such a ground station.

If this chain of argument, which heavily relies on the information found in the Iranian documents, implies that Iran has not assimilated guidance and control (G and C) technology enough to fabricate its own system suitable for use in space launch. It also shows, however, that Iran wants to solve this problem itself as much as possible and not rely on importing complete G and C systems.

UPDATE (4 March 2010): I was going over some Iranian presentations and came across (once again) this presentation by the Iranians to the Feb. 2009 meeting of the UN Committee of the Peaceful Uses of Outer Space. This page clearly indicates a difference between satellite ground stations and ground facilities devoted to the powered phase of the Safir. Note that it says “Tracking, Telemetry, and Command Stations.” I have added the underlining in this image to highlight what I consider are important points.

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The Atlas V that carried the Solar Dynamics Observatory into orbit on 11 Feb. 2010 created shockwaves that rippled through a cloud layer. I’ve counted 11 distinct shockwaves, marked by arrows in this image.

Ok, this has little if anything to do with security or arms control (well, perhaps a little) but it is such fun that I couldn’t resist writing about it. And it is certainly very educational. There is a very fun video of the Solar Dynamics Observatory launched on February 11, 2010. In that video (and in the image above) you see the SDO’s Atlas V launch vehicle passing through a cloud layer, with shockwaves radiating out. Of course, the shockwaves are generated by the missile and the cloud layer is only providing a way of seeing them. In fact, what is visible is not a single shockwave radiating through the cloud layer but rather multiple shockwaves passing through the layer. As these shockwaves “follow” the missile, each point of intersection with the cloud layer moves outward. I’ve tried to indicate this with the cartoon below:

Shockwaves are formed at “discontinuities” along a rocket’s airframe. They radiate energy away from the point on the missile where they are created. As the missile moves along, this constant creation of shocks form what appears to be a continuous “cone” that trails along the rocket. The angle the cone makes with the rocket is therefore related to the rocket’s speed. Of course, the more discontinuities there are on the airframe, the more shockwaves are formed and the more energy is radiated away. That, by the way, explains why the “baby-bottle nose cone” of the Ghadr (also sometimes know as Shahab-3B and various other names, I wish we could all agree on names) has a higher drag coefficient than the simple cone on a Nodong or Shahab-3. Of course, as my friend and fellow former UNMOVIC inspector, Mike Elleman points out, the baby bottle shape allows the weight to cross sectional area of the detached warhead to be increased. This ratio is also know as the ballistic coefficient or Beta of the warhead and allows both a faster reentry and a more stable trajectory.

I’ve been able to make a rough correspondence between the number of discontinuities on the Atlas V and the number of shockwaves visible in the cloud layer. (See the image at the top of this post as well as the images to the left.) Of course, not all discontinuities make shockwaves that are visible around the entire vehicle. For instance, the vehicle’s airframe shields a whole hemisphere from a shockwave caused by a pipe sticking out on one side. But this correspondence is close enough to really illustrate this physical process.

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The February 11, 2010 test of the ALTB (the small, slightly horizontal blip on the right) against a target missile, the larger blip on the left. The target blip size is dominated by the exhaust plume.)

On February 11th, 2010, the Air Force successfully tested its Airborne Laser Test Bed (the new name for what was developed as the Airborne Laser or ABL). Since the ABL was how I got into this business, I feel a certain interest in its continued development. Others, especially Jan Stupl who is a Science Fellow at Stanford’s CISAC, have done a more complete analysis since I did my study (also as a CISAC Science Fellow ) on the ABL. Jan’s thesis at Hamburg University involved authenticating a finite element simulation of a laser heating up a rocket’s airframe by actually comparing it with experiments he did. I consider his study to represent the current state-of-the-art knowledge in the nongovernmental community. (While at CISAC, Jan has extended that study with a very important analysis of using lasers as anti-satellite weapons.)

I think my most important contribution to the ABL discussion was in presenting a way of thinking about laser missile defense engagements. This is summarized by this graph, which shows the two important curves for determining a laser’s effectiveness, which can be characterized by the length of time it takes the laser to heat up the rocket’s skin enough for internal stresses to break the missile apart. (See Jan Stupl’s work for more accurate time estimates.)

An example of how to think about laser engagements. It depends on the nature of the target missile as well as the laser’s energy; both of which are uncertain.

One graph, the “visibility” curve, shows how long the missile is visible to the ABL while it is under power. (The ABL’s kill mechanism requires that there be a large axial load on the airframe that is only there while under power.) As the ABL gets farther away, the Earth’s curve hides more and more of the powered flight either behind the Earth’s limb or, perhaps more likely, behind a large barrier of atmosphere that disrupts the laser beam. On the other hand, the farther away the laser is, the long it takes to deposit enough energy to cause a failure. That is represented by the graphs that are increasing dramatically with distance. The distance at which these two types of curves cross is the maximum range of ABL.

Videos of the February 11th test have been altered to mask the time of the actual engagement. (That is what they say at the start of each video segment.) My guess, based on how fast pieces seem to fall away, is that they have been sped up. Which, of course, makes the laser seem more effective. Another apparent feature of the videos is how close the target and the ALTB are. This has two effects. Most importantly, the engagement is much farther down the “time required” curves. But it also means a given change in the missile’s position, as it accelerates along its trajectory, will produce a bigger angular displacement as viewed from the ALTB. That should mean it is easier for the onboard targeting systems to follow the target. It also appears that the ALTB is pointing down when it fires. This could, of course, be an artifact of the position of the camera. However, if it is true, it means both that the laser is firing through more atmospheric turbulence (an impressive achievement) and that the rocket is moving slower than it would if it was allowed to gain altitude. The later means, of course, that it is easier to shoot down.

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The first three pieces of debris cataloged from the Yaogan 1 breakup are shown. The approximate time of the incident (2/4/10 at 6:49 UTC) was determined by “backtracking” the pieces. The fact that the debris and the remainder of the satellite do not exactly “match up” indicates errors associated with the orbital measurements.

Yaogan 1, a Chinese Earth Observation Satellite, erupted into multiple pieces last week. By back-tracking the pieces, I believe the date and time of the incident was February 4, 2010 at about 6:49 UTC. It is interesting to note that the maximum difference in orbital speeds is about 22 m/s. That can be compared with the hundreds of meters per second typical in a collision. Judging by past experience, a few more pieces of debris will be cataloged in the days to come. Yaogan 1 would have been four years old this April (launch date: 27 April 2006).

Just to be complete, there is no indication that this was anything other than an internal explosion. While the original satellite might appear in this particular view to be over China at the time of the incident, it is actually well over the Ocean.

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Iran’s aerospace program has been so active in the last few years it should be possible to say something about their development philosophy: the technological arc or trajectory they are following. For instance, why did they “jump” from SCUD-type missiles to the Shahab-3-type? Why didn’t they put a higher priority on clustering engines in order to achieve greater ranges before moving on to the Shahab-3? Many of my friends believe they should have. A large portion of their argument is centered on the fact that they believe Iran would have established a missile capable of hitting Israel much sooner if they had done that, perhaps as early as the mid-1990s. Of course, such arguments place an extraordinary amount of emphasis on such a military objective, especially when Iran’s nuclear program was much, much less advanced.

I’ve always thought, however, that Iran did make a strategic decision about the direction its missile development program was going in. But it was not a military-strategic decision but an industrial-strategic decision even if there were military advantages to be had further down the road. I believe Iran decided they needed to assimilate the technology for producing large engines indigenously and that this was a much higher priority for them than early production of a longer range missile. New images released at the same time as the “Kavoshgar-3” sounding rocket (with its animal passengers) was launched. Two amazingly important images were released:

A new, large, two-stage rocket with the Iranian space agency logos on it. The second stage appears to be the same stage (and nose fairing) as the Safir’s second stage.

Assuming that the smaller diameter second stage is the same as the Safir’s second stage (with a diameter of 1.25 meters), then the much larger first stage is consistent with a diameter of 1.95 meters. That is, of course, considerably smaller than twice the Shahab-3’s diameter of 2 times 1.25 (or 2.5) meters. So it is fair to ask “What can you put in there?” I think the answer is a cluster of four “Nodong engines.” And, voila, the Iranians show a new rocket power plant with a cluster of four Nodong engines at the same gathering where Pres. Ahmadinejad watched the Kavoshgar-3 launch:

An Iranian rocket scientist unveils the new cluster of four Nodong engines, known as the Phoenix (if Google translate is working properly). The yellow struts above the engines are for transmitting the thrust to the rocket’s airframe. Their presence implies that the first stage will use jet vanes for thrust vector control.

Phoenix, the name of the new power plant, is an interesting name. I’m not sure what the Iranian mythological implications are but as a Westerner, to me it means rebirth in fire. Perhaps they are implying the rebirth of this engine design in a new form. Of course, it is always dangerous to use one cultural point of view to analyze another culture’s literary allusions.

The yellow struts rising above the engine cluster (and their multiple turbopumps, perhaps four? one for each engine?) are for fastening the power plant to the rocket body and for transmitting the thrust they develop. They are angled slightly outward for increased structural strength. Pads at the top of the struts are the connections with corresponding strong points inside the first stage. But is the first stage wide enough to accommodate this cluster?

To answer that question, I have had to go through a chain of photo-interpretation; each of which undoubtedly contributes a certain amount of uncertainty or error to the final answer. First, I had to determine the diameter of the Nodong engine. (I know these are Shahab-3 engines, but I am so used to calling them Nodongs, it would be too painful to switch. Let it be known that I think these engines are indigenously produced in Iran, though Iran probably bought or licensed the production line for them from North Korea.) I get a diameter for the combustion chamber, just below the strong points for the struts, of 0.57 m.

Then, transfer this diameter to the image of the Phoenix power plant:

The top of the Phoenix power plant, showing the combustion chambers and the full diameter of the struts. Calculations by the author indicate that this cluster of four engines would certainly fit inside the large rocket body shown above.

Using this combustion chamber diameter as a reference point on length, I get a total separation between opposite pads at the top of the struts of 1.87 meters. Of course, a rather long chain of analyses was needed to estimate this length. And even the assumption that the farthest right strut pad and the farthest left strut pad represent the full diameter of the support system introduces a certain amount of uncertainty (though that is reduced by a cosine theta effect). Nevertheless, this is remarkably close to my estimate for the diameter of the new rocket’s first stage. Close enough to convince me that this is the new first stage’s power plant.

Note that there are at least superficial differences between this rocket’s first stage and the DPRK’s U’nha-2’s first stage. If nothing else, Iran has designed the airframe itself. (I am being extra cautious about this, my own feeling is that Iran has designed the entire first stage itself. But that is such a key step in my understanding of Iran’s missile development trajectory, that I am hesitant to state it as a conclusion.)

So what do I think has happened? First, Iran purchased a production line for Nodong engines (and the other components of the Shahab-3 missile) from North Korea. However, though the years of producing them, flight testing Shahabs, and modifying them with the design and production of the Safir and other rockets, Iran has fully assimilated this technology and they are moving on to the next stage of development—clustering large engines (they obviously gained some highly important experience with the cluster of two engines on the Safir’s second stage)— and they are probably doing this largely on their own.

Note: a future post will estimate the range of this missile using the “hypothesis” developed here.

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These two views show a target warhead 350 km directly above the Jiuquan Satellite Launch Center at 7:45 pm (local time) on 11 January 2010. The image on the left shows what the target warhead (with an altitude of 350 km) would see if it looks at the Sun and the right shows the geometry of the Sun, Earth, and target warhead at at that instant.

I am starting to conclude that the “eyewitness” to the Chinese missile defense test is probably real, the reported time (7:45 pm, “local time”) is reasonable, and the target vehicle was most likely a relatively short range missile such as the DF-21. The slower the target vehicle, the more reasonable the streak seen on the camera phone’s image becomes. One very important question can still be addressed: was the target illuminated by the Sun? The answer to this question is vastly important. If the target could not be illuminated by the sun, it would mean that the Chinese have developed much more sophisticated infrared sensors than they have flown previously. If, on the other hand, it could be illuminated by the sun, perhaps by selecting an intercept point high enough for the sun to illuminate the target, then we are not forced to conclude a dramatic improvement in IR technology.

7:45 pm sounds pretty late at night. (Especially during the winter!) However, we must not forget that China is a very large country that uses a single time zone. That means that when it is 7:45 pm in Beijing, it is also 7:45 pm local time at the Jiuquan Satellite Launch Center almost 1,400 km west. On 11 January 2010, that corresponded to11:45 UTC. How high up would the target have to be to still be illuminated by the Sun?

At that time, the Sun was 17.4 degrees below the horizon at Jiuquan SLC. It’s a simple exercise in geometry to show that an object needs to be at an altitude of 305 km or greater if it is to be illuminated by the Sun. That is easily achievable by a DF-21 flying a maximum range trajectory.

I suppose that some people will still want to believe that China has achieved a quantum leap in IR technology. I cannot prove them wrong. However, I believe that such improvements come in systematic ways; especially if the developing country wants to master the technology for the long term. This test is still consistent with the Chinese hit-to-kill technology using a visible light tracker.

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I’ve been working on a rather long piece about the recent Chinese Ballistic Missile Defense test but persistent reports of an eyewitness (complete with photos) have sidetracked me. These reports purport to be from a Chinese citizen who appears to have witnessed multiple flashes/explosions. (The original English translation seems to have disappeared, luckily I printed it out to pdf, which can be viewed here.) The question is: are these credible reports/photos?

For the moment, let us assume the photograph is associated with the interception. What could it be? My guess is that it is not the initial interception. The eyewitness seems to have watched a number of phenomena in the sky before taking out his cell phone and taking a picture. (That is certainly believable. In fact, it would be too incredible a coincidence for him to capture the interception.) Also, the first things he witnessed do not appear to have been the plume from the interceptor rocket. He certainly would have reported an initial streak of light if that had been the case rather than “moons” appearing.

Instead, the image above could be a large fragment from the target burning up in the atmosphere as it reenters. Using a typical camera phone field of view of 50 degrees implies that the streak is about 1 arc second long. If it originates at about 50 km altitude—somewhere around the altitude where the atmosphere starts to get fairly dense—then that corresponds to about 0.8 km long. Of course, it has been foreshortened by some unknown amount.

For the moment, and for the sake of continuing to speculate, let us assume there is no foreshortening. We might expect a target velocity (depending on the unknown range of the target rocket) to be somewhere between 3 and 6 km/s. With no foreshortening, that implies a “shutter” time of between 0.15 to 0.3 seconds. (Shorter range target rockets would imply longer shutter times.) I’m not an expert on cell phone cameras, but that seems to be somewhat longer than I would expect possible. (Readers?) The inevitable foreshortening would lengthen that shutter time still further and assuming a higher altitude would imply an even longer shutter time. These same arguments rule out this being an image of the initial interception. So the credibility question comes down to: how long does a cell phone camera integrate over a scene at night?

There is still some wiggle room here. I need to try to calculate where in its trajectory (ie what altitude) a piece of debris would become visible but my initial reaction— subject to a lot of further work —is that this is not directly associated with the interception. It is still possible that it is a piece of debris burning up.

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The most recent satellite reported to be joining China’s constellation of Beidou navigation satellites is shown in yellow. An example of a geostationary Beidou satellite is shown in white and China’s one and only navigation satellite in a medium Earth orbit (MEO) is shown in green.

The launch of what is reported to be a seventh Chinese navigation satellite (on 16 January 2010) provides an opportunity to review what we know about this system of satellites. First, it is clear that the satellite, which has yet not been officially designated a Beidou satellite on the NASA space-track website (at least as of 12 noon, 18 January 2010), is intended to be a geostationary satellite. It, and the third stage of the CZ-3 launch vehicle, are in a geostationary transfer orbit (GTO), as the image above shows. Within a few days of launch, the satellite’s apogee motor will fire, positioning the satellite in to its final orbital.

If the case of Beidou 1D is any indication, we will not know which satellite it is replacing until China moves it into position. China, as a responsible spacefaring nation, moved Beidou 1D into a supersync orbit just days after the launch of its replacement satellite, Beidou G-2. Beidou 1D as only about two years old when China replaced it with what is reported to be a second generation Beidou satellite. That is somewhat surprising since Beidou 1 was over six years old at the time and one might have expected it to be replaced before the much younger 1D. If China decided to replace 1D because it was failing, they must have had plenty of warning since they were still in control of that satellite.

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Current Beidou Constellation is shown (at the top) with the ground tracks for three orbits for each satellite projected onto the Earth’s surface; (lower left) an equatorial view of the satellites; (lower right) a polar view of the constellation. Note the Beidou 1D’s ground track shows both a large longitudinal displacement over three days and a large inclination—the up and down motion of the ground track. Dates indicated are the launch date of each satellite.

China’s first generation of navigational satellites did not have an onboard atomic clock. That, of course, complicated their operation and limited the number of users. Instead of broadcasting their own timing, as GPS satellites do, the satellite operated as a “bend in a pipe” with the time standard generated on Earth and, in fact, the “user” position determined by a central location after a round trip of radio signals from the center to the satellite to the user and back. It would be very interesting to know if the second generation satellites had their own space qualified atomic clocks.

With this latest satellite, we are also starting to see a pattern in Beidou launches. About every three years (2000, 2003, 2007, 2009*, 2010) a new wave of satellites is plugged into the constellation. (The asterisk for 2009 indicates that this launch might well have been accelerated to replace a dying satellite.) That might indicate the length of time it takes to design and/or build a new satellite. If it includes design time, I would expect evolutionary changes; something we might expect from China in any case given their known history of systematic development.

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Quite a few of my friends have been urging me to write something about the “new” images of Iran’s space center that have shown up recently on Google Earth.

The trouble is, I hate rehashing stuff I wrote about almost two years ago when I “discovered” the facility—much like Columbus “discovered” America—and wrote about it in Jane’s Intelligence Review (see Geoffrey Forden, “Smoke and Mirrors: Analyzing the Iranian missile test”, JIR, April 2008, pp. 47-51; I have never understood how the editors pick titles for my papers).

Perhaps the most interesting part of the imagery now, given the connection between these two countries’ missile programs, is the similarity between a building at North Korea’s launch site and one at Iran’s. For those who would like to examine the site themselves, let me replicate the coordinates I published in the open literature for the first time nearly two years ago:

35.234440° N, 53.920798°E.

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