Fogbank: That time the US forgot how to make Nukes

The U.S nuclear weapons program is extremely secretive, yet oddly we can still figure some things out about it from the information that is out there. The U.S department of Energy, the government department concerned with the safety and handling of nuclear material, is in charge of one of the largest nuclear stockpiles in the world, and those weapons need to be constantly upgraded and refurbished with newer technologies. Occasionally those technologies get hinted at by politicians when asking for more money, or defending delays, and sometimes its clear that processes to create technologies have been forgotten with engineers retiring. The secret material, publicly refereed to as Fogbank is a great example of this.

Aerial photo of the Y-12 facility
Aerial photograph of the Y-12 facility at Oak Ridge taken around 2007 (Credit: NNSA)

Fogbank first became well known around 2007, when it came to light that it was the root problem behind technical delays in the life extension project for the W76 warhead. This particular warhead is used on the Trident II, submarine launched ballistic missiles. They are known as D5s, and are used by both the U.S Navy, and and the Royal Navy of the UK. It took until 2018 before the W76-1 warheads were finally delivered.

A Trident II (D-5) launch from a submerged Royal Navy submarine
A Trident II (D-5) launch from a submerged Royal Navy submarine. Image from Lockheed Martin, but is a U.S. Department of Defence photo.

There is a material that we currently use and it’s in a facility that we built … at Y-12 … It’s a very complicated material that – call it the Fogbank. That’s not classified, but it’s a material that’s very important to, you know, our [W76] life extension activity.

The then NNSA director Thomas D’Agostino, talking to members of the House of Representatives in 2007. He is referring to the Y-12 National Security Complex, located near Oak Ridge.
Y-12 Security Complex
The Entrance building of the Y-12 security complex, a Department of Energy facility located near Oak Ridge (Credit: NNSA).

Late in 2007, D’Agostino described Fogbank as an “interstage material”, which heavily implies that it sits somewhere between the primary and secondary stages of the the two stage thermonuclear weapon. The W76 is a two stage warhead, so would need some sort of material to trigger the second stage. In a thermonuclear bomb, also known as a H-bomb, the first stage creates the easily produced fission reaction (what happens in a nuclear reactor), which creates a superheated plasma at the interstage (the expected role of Fogbank), which then triggers the fusion reaction in the second stage. Fusion is the process that happens in the Sun, and may be the way we power future nuclear reactors.

There’s another material in the [W76] – it’s called interstage material, also known as Fogbank, but the chemical details, of course, are classified,

Thomas D’Agostino speaking to senators late in 2007
NNSA director Thomas D’Agostino in 2009 (Credit: NNSA)

This has obviously lead to many engineers and scientists to comment on possible materials that Fogbank could be. The most common reccuring theme is that it is likely to be an Aerogel, a type of material known as an ultra light gel. Aerogels are extremely light while being surprisingly strong. Invented in the 1930’s, the concept of aerogels have been around for a long time, but it was NASA’s Glen Research Centre that introduced modern methods of manufacture, and even used them on a few space missions such as Stardust. There have been suggestions, such as the one from Jeffery Lewis, an expert on missiles and nuclear weapons, that the code name Fogbank could be a reference to the other nicknames for Aerogels. Names such as “frozen smoke” and “San Francisco fog” have all been used in reference to the light and almost see through solid.

The Stardust dust collector with aerogel blocks. (NASA)
The dust collector with aerogel blocks on NASA’s Stardust spacecraft. (Credit: NASA)

There are a few other things that imply that Fogbank could be an aerogel. In 2007, D’Agostino told legislators that Fogbank’s production process required the material to be purified using “a cleaning agent that is extremely flammable.”. Then in that same year he talked at the Widrow Wilson centre about “another material that requires a special solvent to be cleaned”, potentially the same material, and that the solvent used was identified as “ACN”, the common abbreviation of acetonitrile, a solvent commonly used in aerogel production. He describes the solvent by saying “That solvent is very volatile, it’s very dangerous. It’s explosive.” which describes acetonitrile well.

A 2.5 kg brick is supported by a piece of aerogel with a mass of 2 g.
A 2.5 kg brick is supported by a piece of aerogel with a mass of 2 g. (Credit: NASA/JPL)

More evidence comes from a 2007 briefing slide on a program known as the Reliable Replacement Warhead (RRW), which aimed to develop a new design of warhead to replace a selection of the existing versions. The slide points at an interstage material that is an expensive, “specialty” material that if replaced would eliminate the need for unique facilities. The RRW effort was de-funded in 2008 and cancelled by president Obama the following year.

NNSA slide from a 2007 briefing
The NNSA slide from a 2007 briefing about the RRW program that details the properties of the current interstage material. (Credit: NNSA)

Up until 1989 the Y-12 facility in Oak Ridge had a specialised site known as Facility 9404-11, which was apparently used to create Fogbank. 1989 was the year that the final W76 warhead was finished, so the facility was closed down and a new “purification facility” took its place. The original building was eventually torn down in 2004, and replaced with a new facility, renamed to Facility 9225-3. According to Denis Ruddy, who served as the president of the division of the Babcock and Wilcox Company (BWXT Y-12) that ran the facility between 2000 and 2014, the purification facility reprocessed a material that they were taking out of weapons so that it can be used in refurbished weapons. The material is apparently classified, and the use in the weapon is classified, and so is the process that they follow, unsurprisingly.

It is also public knowledge that this site uses ACN as a part of at least one of the processes going on in it. On three seperate occasions in March 2006, workers had to evacuate the facility after alarms were triggered. According to the Department of Energy, the facility is alarmed to monitor for ACN levels, but it is not confirmed whether the alarms that went off were from ACN. There was also an ACN spill that forced an evacuation of the facility in December 2014, and although there were no injuries, it took months for the facility to get back up and running.

The Purification Facility, also known as Facility 9225-3, at Y-12.
The Purification Facility, also known as Facility 9225-3, at Y-12.

In 2009, in an issue of the Nuclear Weapons Journal, an official publication of the Los Alamos National Laboratory, an article was published that disclosed that there was a decision to restart the manufacture of Fogbank in 2000, and confirmed that it was linked to the W76-1 warhead project. It also revealed that in the years between the projects that the NNSA had lost almost all of its institutional knowledge base regarding the manufacture and development of Fogbank. The article said “Most personnel involved with the original production process were no longer available.” So the newer personnel had to reconstruct the production process from the records. It also mentioned that “a new facility had to be constructed, one that met modern health and safety requirements.” The facility would make sense to be the 9225-3 facility as it stands on the site of the old one. The best part of it all, the new facility, with the new staff using old records to manufacture, created a higher purity final product than the initial W76 warheads used. The problem with this “improved” material was that it was actually too pure,the impurity was actually essential for the final product to work as intended. The process was concluded in 2008, almost a decade after first deciding to restart production, and the W76-1 warheads began that year.

The improved production process
The extremely vauge diagrams shown in the article describing the production process the NNSA initially developed to produce Fogbank in the 2000’s and the improved versions. (Credit: NNSA)

This is one example of how organisations such as the NNSA lose technical institutional knowledge over relatively short periods of time when the technology isn’t being used. They had similar problems with designing high explosive capabilities recently. In March 2020, The director of the Natural Resources and Environment team at the Government Accountability Office, Allison B. Bawden, highlighted that the NNSA had not produced a particular type of high explosives at scale since 1993, and highlighted the issues with Fogbank production as an example. This highlights one issue of governmental technology not being taken on by commercial business to continue. Either way, Fogbank is a prime example of the complexity, and secrecy of nuclear warhead production, and how in that secrecy, technology is lost.

Considerations When Making a Current Shunt Sensor

For battery powered projects, current consumption is a really important consideration when designing the circuitry. While designing my final year project I spent a huge amount of time researching how to put together a simple current sensor. Considering most applications for me are DC, fairly low current and low voltage, the most obvious design is to make a current shunt. The basic idea of a current shunt is that you put a very low value resistor between the circuit you want to measure and ground, and measure the voltage across it. When one side is of the shunt resitor is ground it is low side, there are also high side versions but are mlre complex. As the resistor has a small resistance, there will be a low voltage drop (usually mV) across it meaning it shouldn’t affect the load circuitry. The voltage will also be proportional to the current running through it, meaning if you measure it, and do the right maths you can get a consistent and reliable current reading. This post is about how to get that tiny voltage into 1’s and 0’s, while thinking about the considerations that have to be made about the design to make it accurate and reliable in the environments you want.

Final Year Project
My final year project needed current sensors on the motors as well as monitoring the drain on the battery.

The first thing that needs to be decided is the shunt resistor itself. A shunt resistor is basically a low value resistor, with very tight and known tolerance usually with a fairly high power rating. It can be used in AC and DC circuitry, with the concept behind it being that as a current flows  though it, a voltage is induced across it. The voltage can then be measured and using a simple calculation (based on ohms law) converted into a value for current. The value of the resistor depends on what it is measuring and what is measuring it. Start with what is measuring it. If you are like me, it is likely that it will be read by an ADC, probably on a 5V or 3V3 microcontroller. The voltage across the resistor is going to be amplified between 10 and 100 times (we will get to why in a moment) so pick a maximum voltage within that range. I tend to go with 100mV maximum voltage drop, which for a 5V ADC would require an amplification of 50. Then, take the maximum value of current you want to be able to measure. You can then use ohms law to figure the resistance you need. For example if I wanted to measure 1A, the resistor would be 100mV/1A = 100 mohm. Now we know the resistor value, use the power equation to work out the power eating we want. For this example we would need P = I V = 1 x 0.1 = 100mW. This is the minimum power rating you need, I personally would get a 250mW or even a 500mW just to keep the temperature of the circuit down.

The simple equation to work out what sizesunt resistor to use. Credit: Texas Instruments 

Now we have a voltage that will be somewhere between 0 and 100mV with reference to ground. We want this value to be scaled up to 0 to 5V. To do this we are going to use an operational amplifier. There are plenty out there, and most people have their favourites and I’m not here to convince you otherwise. I tend to use an op amp that I am using somewhere else in the circuit to make life easier. There are a few things you do need from an op amp in this circuit though, it needs to be rail to rail, and have a low input offset voltage. Offset voltage in an op amp is the voltage difference on the inputs, and even though they are tiny differences they can have a big effect because we are amplifying small voltages, and any noise or offset will be amplified too. The op amp needs to be in a simple non inverting configuration. The equations needed to design this are in most first year textbooks and there are plenty of calculators online. I have set a gain of 50 in my calculation, which is in the fairly common range. The output of the amplifier can then go straight straight into an ADC to be measured.

The basic layout of a current shunt sensor showing where the shunt resistors and gain resistors go in the circuit. Credit: Texas Instruments 
The first version of my current sense test circuit, using an OP170 made by TI.

Now let’s look at a few places where errors can come into a design like this. There are two types of errors that occur in a circuit like this, gain error and offset error. A gain error is one where the output error gets further away from the ideal output as the current gets higher. An offset error is one that has the same amount of error whatever the input, just like an offset. The only common source of offset error in a circuit like this is from the offset error in the op amp discussed previously, solved with an improved choice of amplifier. The gain errors are usually due to a difference in resistance from the ideal. Many things can cause this, one is the tolerance of the resistor used, we want to use a precision resistor of 1% or less tolerance. Another cause could be temperature changes in the resistor itself, it may be next to a large MOSFET or other hot component, or could have too low of a power rating making it heat up, wither way a change in temperature means change in resistance. Layout can also be an issue, if tracks are too thin or too long they can add extra unwanted resistance.

Great graphs showing the difference between gain an offset error. Credit: Texas Instruments.

If you want to add a bit of fancyness into the project, or really need to measure down to low currents, you need to tackle the zero-current error. The problem is that when using an op amp, even a rail to rail one, it never quite reaches the power rails. Even the best ones can only get within 100mV or so of the power rails, this is known as saturation. Solving this involves moving the power rails slightly so the saturation point is less than ground. If you have a negative voltage rail you can use that but home projects tend to be single supply, so we need another power source. This can be made using a voltage inverter (a type of charge pump). Usually only needing an external capacitor to work, they are cheap and easy to integrate into a project. I used a LTC1983, which creates a negative 5V rail, but there are plenty of others such as the LM7705. Research what fits your circuit and cost point, and just attach the negative output to the negative supply rail of the op amp.

 A great graph showing how the zero current error occurs, and what it would look like if you tested it. Credit: Texas Instruments.

Most issues with error can be fixed during the hardware design phase. You can pick better op amps, such as ones designed to combat offset voltage. Some amplifiers have internal calibration procedures, and some such as chopper stabilizers are specifically designed to correct these problems. You can also use a potentiometer instead of a power resistor, but they are more susceptible to temperature and can be knocked. Another way is to fix issues in software by creating a calibration procedure. Using a calibrated precision current source and a multimeter, measure the reading of the ADC and compare the value to the reading from the instruments. You should get an offset and gain value that can then be used to calibrate the sensor.

A simple set up that I used to calibrate an early sensor, with a big power resistor as the load and a variable power supply to change the current. Marked down to put into calibration.

I would suggest trying out a few of these sensors in future projects, they don’t cost too much, and can be a valuable addition to a design. Especially for power sensitive devices, or smart sensors, this could be a better solution than an off the shelf or breakout board solution. If you want to hear more about my current sensor designs, and how well the testing and calibration went then comment or tweet at me. I already have some documentation that I may release at some point.

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Record Breaking Falcon 9 Launch

Telstar 19V
The awesome flames of the Falcon 9 Block 5 carrying Telstar 19V. Credit: Marcus Cote.

On the 22nd of July 2018, at 05:50 UTC a record breaking Block 5 Falcon 9 launched Telstar 19V into subsynchronous transfer orbit. Launching from Cape Canaveral Space Launch Complex 40, F9-59 (launch designation) was the First Block 5 to launch from this pad. The 7,075 kg payload was more than the previous record holder, the 6,910 kg TerreStar 1 orbited by the Ariane 5 in July 2009. Although, the previous record holder launched the satellite to full geosynchronous transfer orbit. This launch was seen as a key test of the newly developed Block 5 launch system. The first stage was recovered on the autonomous drone ship “Of Course I Still Love You” off the Florida coast.

Telstar 19V medium
A great view of SLC-40 from across the water while Telstar 19V is being launched. Credit: SpaceX Flickr.

An SSL 1300 series satellite, Telstar 19V is part of the Telstar series. Owned by the Canadian Satellite Company Telsat, it was built by Space Systems Loral (MAXAR). Using Ka and Ku band transponders it is branded as a high throughput communications satellite, designed for high bandwidth applications that the communications industry is currently dealing with. It is collocated with Telesats Telstar 14R satellite at the same position. The companies first high throughput satellite was Telstar 12V, which sits 15 degrees west.

The upgraded engines of the Merlin 1D engines on the Falcon 9 block 5 can produce a total of 775.65 tonnes of thrust at sea level. The second stage produces roughly 100 tonnes of thrust when in space. The first stage with the designation B1047 burned for 2 minutes and 30 seconds before separating to perform reentry and landing burns. The second stage burned for 5 minutes and 38 seconds to reach a parking orbit, stopping T+8 minutes 12 seconds. The stage restated at T+26 minutes 49 seconds for a 50 second burn to put the satellite into a 243 x 17,863 km x 27 degree orbit. The satellite will then raise itself into a geostationary orbit at 63 degrees west to cover the Americas.

Telstar 19V long exposure
A great long exposure of F9-59 launching Telstar 19V from Florida’s Cape Canaveral. Credit: SpaceX.

A total of 26 Falcon 9/Falcon Heavy core and booster stages have now been recovered in 32 attempts. Four of those successful landings have been on “Just Read The Instructions” off the California coast, 10 have been at Cape Canaveral Landing zone 1&2, and 11 on “Of Course I Still Love You off the Florida coast. Twenty unique first stages have been recovered, with fourteen of them flying twice, and eight being expended during their second flight. All of the successfully recovered first stages have been version 1.2.

Telstar 19V medium 2
A Falcon 9 launches from Space Launch Complex 40 with a record breaking satellite aboard. Credit: SpaceX Flickr.

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

The Final Block 4 Changes the Florida Sky

Smoke left over by CRS-15
The smoke stream left over by CRS-15 after the launch from Cape Canaveral, FL. Credit: Marcus Cote.

On the 29th of June 2018, at 09:42 UTC the last Block 4 type Falcon 9 rocket launched a cargo mission to the International space station. Launching from Space Launch Complex 40 at Cape Canaveral Air Force Base, the Falcon 9 was carrying CRS-15, a resupply for the International Space Station (ISS). This is the 15th mission of up to 20 CRS missions that have been contracted with NASA to resupply the ISS. Initially planned for April 2018, it was eventually pushed to the 29th of June. Previous resupply missions have been conducted by SpaceX and Orbital ATK.

Long Exposure CRS-15
A great long exposure image of the CRS-15 launch. Plenty of other versions of these out there, but this one has the great smoke shapes at the end. Credit: Marcus Cote.

B1045 (the first stage booster) was the seventh and final “Block 4” Falcon 9 v1.2 first stage manufactured by SpaceX. For this reason it is very likely that this was the final Block 4 first stage orbital vehicle. SpaceX has since developed the Block 5 the debuted in May. Together the seven Block 4 Falcon 9’s boosted twelve missions, with most being expended on the second flight. This stage was purposely expended at the end of the mission, the ninth purposeful expenditure in the last twelve launches. This stage was not equipped with landing legs or titanium steering grid fins. It was the 14th flight of a previously flown Falcon 9 first stage, and the eighth to be expended on the second flight.

CRS-15 by Spacex
The night launch of the CRS-15 mission to resupply the ISS with a Dragon capsule. Credit: SpaceX

B1045.2 had previously boosted NASA’s TESS towards orbit on April 18th 2018, I wrote about that launch here. With it returning to the autonomous drone ship “Of Course I Still Love You” downrange. For this mission it launched the two stage rocket and powered it for 2 minutes and 51 seconds. With a Dragon 11.2 refurbished spacecraft that was previously used on CRS-9 in July 2016 the main payload for the rocket. The first put the capsule and the second stage into a 227 x 387 km x 51.64 degree orbit. The block 5 second stage burned for about 8 minutes and 31 seconds after liftoff, inserting Dragon into the required orbit. The burn was 36 seconds shorter than previous Block 4 launches as this rocket had higher thrust. Dragon rendezvoused with the ISS on the 2nd of July after an extended coast.

CRS-15 smoke
The great view of the remanence of the CRS-15 launch, taken from the Vehicle Assembly Building at Cape Canaveral. Credit: Marcus Cote.

This launch left a particularly cool looking smoke cloud afterwards. With many Twitter users posting images of the smoke remnants hundreds of miles away. The night launch also allowed for some great photos by many of the keen photographers that are at every launch, capturing many of the images in this post. To see more of the awesome rocket launches, I have posted about many, and will continue to do so.

CRS-15 launch
The launch of the CRS-15 mission. You can see the flames from the 9 Merlin-1D engines. Credit: SpaceX

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

The First Block 5 Launches Bangladesh’s First Satellite

F9-55 launches
An awesome image of the first Block 5 Falcon 9 taking off from LC 39A at KSC. Credit: SpaceX Flickr.

On the 11th of May 2018, at 20:14 UTC the first ever block 5 Falcon 9 rocket launched Bangabandhu 1 into geosynchronous transfer orbit. Launched from Launch Complex 39A at Cape Canaveral Air Force Base, the F9-55 (launch designation) was delayed after an automatic abort on May 10th, 1 minute before liftoff. Bangabandhu 1, a Thales Alenia Space Spacebus 4000B2 series satellite is Bangladesh’s first geostationary communications satellite.

The block 5 has been long awaited by SpaceX fans, with many images in the news, and plenty of hints on Twitter. SpaceX has been incrementally improving and upgrading the Falcon 9 v1.2 booster design since it’s first launch in December 2015. Designed to be much easier to refurbish, with potentially 10 reuses in each booster. Previous block designs have only been able to be reused once before being decommissioned.

F9-55 on the pad
The F9-55 on the launchpad ready to fire a satellite into GTO more efficiently that previous versions. Credit: @marcuscotephoto on twitter.

The Block 5 incorporates higher thrust Merlin 1D engines that have turboprop modifications that were requested by NASA. These modifications are to accommodate future potential crew launches. Another big change was mentioned in the livestream, where the pressurisation method in the second stage has been improved. After the AMOS 6 Falcon 9 explosion, the new version allows for faster, later and denser, chilled kerosene fuel loading. It also has new landing legs that can be retracted without being removed like previous Falcon 9’s. There are other changes, but they have been featured in previous designs.

F9-55 launch
The Falcon 9 takes off with Bangladesh’s first geostationary communications satellite on board. Credit: @marcuscotephoto on Twitter

The first stage had designation B1046. It burned for 2 minutes and 31 seconds, before separating ro perform reentry burns. It opened its new landing legs and landed on the autonomous drone ship Of Course I Still Love You, 630km downrange in the ocean. The second stage burned for 5 minutes and 43 seconds to reach parking orbit at T+8 minutes and 19 seconds. It then restarted ar T+27 minutes and 38 seconds for a 59 second long second burn that accelerated the craft to GTO.

F9-55 awesome shot
The Falcon 9 after an aborted launch the day before, with a new paint scheme to denote the block 5. Credit: SpaceX Flickr.

In the 31 attempts, 25 Falcon 9/Falcon Heavy booster have been successfully recovered. Four of the landings have been on “Just Read The Instructions” off the coast of California. 10 on land at Cape Canaveral from LZ1 with another one on  LZ2. 10 have landed on the autonomous drone ship, Of Course I Still Love You off the Florida coast. Nineteen individual first stages have been recovered, eleven have flown twice, with five of those ether expended or lost during their second flights. All the recovered stages have been v1.2 Falcon 9’s.

F9-55 power
The first look at the extra thrust on the Falcon 9 Merlin 1D engines in the new Block 5. Credit: SpaceX Flickr.

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

Falcon 9 Re-Supplies the ISS on CRS-14

Launch of CRS-14
Threatnigh thunderstorms, an image taken by a sound triggered camera at Space Launch Complex 40. Image from @marcuscotephoto on twitter.

On April 2nd, 2018 at 20:30 UTC a Falcon 9 took off from Launch complex 40 at Cape Canaveral AFB. Aboard was a refurbished Dragon capsule with CRS-14, a resupply for the ISS. This was the 14th of up to 20 CRS missions contracted with NASA, with new Crew Dragon variants soon to be used. The capsule safely reached the ISS and was docked 20 minutes earlier than planned. The cost of the mission was reported to be around $2 billion, and comes under a contract between NASA and SpaceX.

Reused Dragon Capsule on CRS-14
The CRS-14 just before launch, carrying a reused Dragon Capsule for CRS-14. Image from @marcuscotephoto on Twitter.

The Dragon capsule carried 2,630kg  of cargo to the International Space Station, including supplies and research equipment. it has 1070 kg of science equipment, 344 kg of supplies for the crew, 148 kg of vehicle hardware, 49 kg of advanced computer equipment and 99 kg of spacewalking gear. Aboard there are a number of experiments, such as a new satellite designed to test methods of removing space debris. There are also frozen sperm cell samples, a selection of polymers and other materials, all experiments to test what happens to different items when exposed to space and microgravity.

CRS-14 launch
Launch of F9-53 on April 2nd 2018, carrying CRS-14 using a reused rocket and capsule. Image from SpaceX Flickr.

Designated F9-53, the Falcon 9 used booster B1039.2, which previously boosted the CRS-12 mission in August 2017, where it returned to landing zone 1. As is customary, the first stage was left “sooty” from it’s first flight. It powered for 2 minutes and 41 seconds before falling back to earth. For the sixth time in the last 7 Falcon 9 launches, the first stage was purposefully expended, even though it carried landing legs and steering grid fins. As with other expenatures, the rocket went through the re-entry landing sequence, but just didn’t have anything to land on and ended up in the sea. It was the 11th flight of a previously flown Falcon 9 first stage, five of which have been purposefully expended during the second flight, only 3 first stages remain that can be reflown.

A Sooty Falcon 9
The Falcon 9 was left sooty after its first flight which has now become the norm. Image from @marcuscotephoto on twitter.

The second stage completed its burn at 9 minutes and 11 seconds after takeoff, to insert Dragon into a Low Earth Orbit inclined 51.6 degrees to the equator. The Dragon 10.2 is a refurbished spacecraft capsule that first flew during the CRS-8 mission in April 2016. CRS-14 was the third launch of a previously flown Dragon capsule. This was also the first time that both the Dragon capsule and the Falcon 9 were refurbished versions on the same rocket. The docking process was carried out for around 20 minutes, and at 10:40 UTC Kanai detached the lab’s robotic arm to hook the free-flying Dragon capsule. At around 12:00 UTC Houston and Canada took control of the robotic arm and maneuvered it to the Harmony capsule of the ISS. It will be unpacked in a very slow process over a number of months.

Falcon 9 CRS-14
A falcon 9 lifting off from Cape Canaveral AFB Launch Complex 40. Image from SpaceX Flickr.

CRS-14 vapour streams
You can see the vapour streams coming off the falcon 9 as it sends its cargo towards the ISS. Image from SpaceX Flickr.

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

SpaceX Launches NEXT 10 Iridium Satellites For a Fifth Time

Iridium-5 Launch 4
The Falcon 9 F9-52 launching with the Iridium NEXT-5 satellites aboard. Image from SpaceX Flickr.

At 14:13 UTC on March 30th 2018, SpaceX launched a Falcon 9 from foggy Vandenberg Air Force Base. Although designated F9-52 this was the 51st Falcon 9 launch. Using a v1.2 variant booster, the rocket delivered 10 Iridium NEXT satellites into orbit. This was the fifth of eight planned Iridium NEXT missions.

Iridium-5 Launch 2
The Falcon 9 lifting off from Vandenberg AFB california. After the fog had lifted. Image from SpaceX Flickr.

 

From Vandenberg AFB Space Launch Complex 4 East, the first stage of the rocket lasted 2 minutes 34 seconds, separating a few seconds after. The second engine fired for 6 minutes 23 seconds. This part of the webcast was purposefully cut short due to a NOAA remote sensing licensing requirements. This is an issue with SpaceX not having the right licence to broadcast images from certain parts of space. This burn placed the rocket in a roughly 180 x 625 km parking orbit. The Thales Alenia Space satellite then deployed an hour after launch, after a second brief 11 second burn. This put the satellites into a 625km x 86.6 deg orbit.

Iridium-5 Long Exposure
A 53 second long exposure of Falcon 9 F9-52 launching from Vandenberg AFB. Image from SpaceX Flickr.

The rocket used another “Fairing 2.0”, which is slightly larger than usual, but equipped with recovery systems. These systems include thrusters, a guidance system, and a parafoil. The ship, named Mr Steven has a large net to capture the halves of the fairing. Again, the ship failed to catch one of the fairings, due to a parachute system issue. In a tweet by Elon Musk, it was reported that the GPS guided parafoil twisted so the fairing impacted the water at high speed. He also said that SpaceX are doing helicopter drop tests to fix the issue.

Iridium-5 launch 3
The Falcon 9 launching, with a view of the surrounding buildings and fuel tanks. Image from SpaceX Flickr.

Five of the six previously used Falcon 9 vehicles have been fully expended, this was the tenth flight of a previously-flown Falcon 9 first stage. Four of these ten have been purposely expended during their second flight. The first stage (B1041.2) was previously flown during the Iridium NEXT 3 launch on October 9th, 2017. It performed the 2 minute 34 second boost, and performed what SpaceX call a “simulated landing” into the ocean. SpaceX appear to be only launching a reused stages for one reflight, with the soon to launch “block 5” likely to be reused multiple times. Currently the company only have 4 first stages that might be flown, with one allocated for the upcoming CRS-14 dragon resupply mission.

Iridium-5 mission 1
The Falcon 9 F9-52 launching with the Iridium NEXT-5 satellites aboard. Image from SpaceX Flickr.

Explorer 1 and the Van Allen Story

On February 1st, 1958 at 03:48 UTC (January 31st at 22:48 EST), the first Juno booster launched Explorer 1 into Low Earth Orbit. It was the first satellite to be successfully launched by the United States, and the third ever, after Sputnik 1 and 2 in 1957. Launched from the Army Ballistic Missile Agency’s (ABMA) Cape Canaveral Missile Annex in Florida, now known as Launch Complex 26. The launch played a pivotal part in the discovery of the Van Allen Belt, Explorer 1 was the start of the Explorer series, a set of over 80 scientific satellites. Although sometimes looked over in the history of space, it guided the US space program to what it eventually became.

William Hayward Pickering, James Van Allen, and Wernher von Braun display a full-scale model of Explorer 1 at a crowded news conference in Washington, DC after confirmation the satellite was in orbit.

In 1954 The US Navy and US Army had a joint project known as Project Orbiter, aiming to get a satellite into orbit during 1957. It was going to be launched on a Redstone missile, but the Eisenhower administration rejected the idea in 1955 in favour of the Navy’s project Vanguard. Vanguard was an attempt to use a more civilian styled booster, rather than repurposed missiles. It failed fairly spectacularly in 1957 when the Vanguard TV3 exploded on the launchpad on live TV, less than a month after the launch of Sputnik 2. This deepened American public dismay at the space race. Leading to the army getting a shot at being the first american object in space.

The launch
Launch of Jupiter-C/Explorer 1 at Cape Canaveral, Florida on January 31, 1958.

In somewhat of a mad dash to get Explorer 1 ready, the Army Ballistic Missile Agency had been creating reentry vehicles for ballistic missiles, but kept up hope of getting something into orbit. At the same time Physicist James Van Allen of Iowa State University, was making the primary scientific instrument payload for the mission. As well this, JPL director William H. Pickering was providing the satellite itself. Along with Wernher Von Braun, who had the skills to create the launch system. After the Vanguard failure, the JPL-ABMA group was given permission to use a Jupiter-C reentry test vehicle (renamed Juno) and adapt it to launch the satellite. The Jupiter IRBM reentry nose cone had already been flight tested, speeding up the process. It took the team a total of 84 days to modify the rocket and build Explorer 1.

Preparing the explorer 1
Explorer 1 is mated to its booster at LC-26

The satellite itself, designed and built by graduate students at California Institute of Technology’s JPL under the direction of William H. Pickering was the second satellite to carry a mission payload (Sputnik 2 being the first). Shaped much like a rocket itself, it only weighed 13.37kg (30.8lb) of which 8.3kg (18.3lb) was the instrumentation. The instrumentation sat at the front of the satellite, with the rear being a small rocket motor acting as the fourth stage, this section didn’t detach. The data was transmitted to the ground by two antennas of differing types. A 60 milliwatt transmitter fed dipole antenna with two fiberglass slot antennas in the body of the satellite, operating at 108.3MHz, and four flexible whips acting as a turnstile antenna, fed by a 10 milliwatt transmitter operating at 108.00MHz.

Explorer 1 parts
A diagram showing some of the main parts of the Explorer 1 satellite

As there was a limited time frame, with limited space available, and a requirement for low weight, the instrumentation was designed to be simple, and highly reliable. An Iowa Cosmic Ray instrument was used. It used germanium and silicon transistors in the electronics. 29 transistors were used in the Explorer 1 payload instrumentation, with others being used in the Army’s micrometeorite amplifier.  The power was provided by mercury chemical batteries, what weighed roughly 40% of the total payload weight. The outside of the instrumentation section was sandblasted stainless steel  with white and black stripes. There were many potential colour schemes, which is why there are articles models and photographs showing different configurations. The final scheme was decided by studies of shadow-sunlight intervals based on firing time, trajectory, orbit and inclination. The stripes are often also seen on many of the early Wernher Von Braun Rockets.

NASM flight spare
The flight ready spare of the Explorer 1, now shown at the National Air and Space Museum.

The instrument was meant to have a tape recorder on board, but was not modeled in time to be put onto the spacecraft. This meant that all the data received was real-time and from the on board antennas. Plus as there were no downrange tracking stations, they could only pick up signals while the satellite was over them. This meant that they could not get a recording from the entire earth. It also meant that when the rocket went up, and dipped over the horizon, they had no idea whether it got into orbit. Half an hour after the launch Albert Hibbs, Explorers System designer from JPL, who was responsible for orbit calculations walked into the room and declared there was a 95% chance the satellite was in orbit. In response, the Major snapped: “Don’t give me any of this probability crap, Hibbs. Is the thing up there or not?”.

Explorer 1 Mission Badge
The official JPL mission pac=tch for the Explorer 1 mission.

The instrument was the baby of one of Van Allens graduate students, George Ludwig. When he heard the payload was going into the Explorer 1 (and not the Vanguard) he packed up his family and set off for JPL to work with the engineers there. He has a good oral history section on this link, talking about designing some of the first electronics in space. He was there watching the rocket launch and waiting for results. From the Navy’s Vanguard Microlock receiving station they watched the telemetry that reported the health of the cosmic-ray package. The first 300 seconds were very hopeful, with a quick rise in counting rates followed by a drop to a constant 10-20  counts per second, as expected. The calculations told them when they should hear from the satellite again, but 12 minutes after the expected time, nothing showed up but eventually, after pure silence, Explorer 1 finally reported home.

The Van Allen Belt
This diagram showcases the Van Allen belts, which were first detected by instruments aboard Explorer 1 and Explorer 3. The Van Allen belts were the first major scientific discovery of the space age.

Once in orbit, Explorer 1 transmitted data for 105 days. The satellite was reported to be successful in its first month of operation. From the scientist point of view, the lack of data meant the results were difficult to conclude. The data was also different to the expectations, it was recording less meteoric dust than expected and varying amounts of cosmic radiation, and sometimes silent above 600 miles. This was figured out on Explorer 3 when they realised the counters were being saturated by too much radiation. Leading to the discovery of the Van Allen Radiation Belt. Although they described the belt as “death lurking 70 miles up” it actually deflects high energy particles away from earth, meaning life can be sustained on earth. The satellite batteries powered the high-powered transmitter for 31 days, and after 105 days it sent it’s last transmission on May 23rd 1958. It still remained in orbit for 12 years, reentering the atmosphere over the pacific ocean on March 31st after 58,000 orbits.

Semi Autonomous Robotic Platform

As part of my degree I had to complete a project as part of the third year in the field of robotics and electronics. I chose to make a robotic platform, a simple idea that could be completed to a high quality with the right amount of effort. What is a robotic platform I hear you ask? well it essentially is a small buggy/rover that that moves around an assigned area completing simple jobs such as transporting goods, picking up parcels or any job that needs a moving vehicle. Usually autonomous, and very expensive, the majority of systems are very application specific. Some simple systems without any sort of control system can cost tens of thousands of pounds, and are not easy for the average employee to operate. Tackling the problem of expensive, application specific robotic platforms was the basis of my project.

4WD robotic platform
The Nexus 4 wheeled drive mecanum robot has an arduino based control system, and mecanum wheels, but will set you back $1500

Named the Semi Autonomous Robotic Platform, the idea was very simple, make a modular system, with building blocks that could be easily interchanged, and didn’t cost the world. These modules were things like motor controllers, sensors and power systems. If a user had a working platform built from this system, it would take minimal effort to swap out any of these modules to bigger motors or better sensors. This means a user can make a robot and only buy the bits they need, and even make their own modules, as long as they fit to the standard written as part of the project.

system block diagram
The initial block diagram of the system, showing how the modules can be controlled in hierarchy structure.

In most robotic systems, mainly to keep costs cheap, there is one controller that controls everything. This idea makes sense for small integrated systems that don’t need to change, but doesn’t really work when systems need to be dynamic. For instance, say you decide that your DC motors driving your robot aren’t giving you the control you want. You source some stepper motors, but this means completely changing the motor controller and therefore the software that controls it. Because one controller is in charge of everything, the software for the whole system needs to be re-written, and re-tested. That small change could have affected any of the other systems that that controller is in charge of. Make a change that breaks something important, you could set back a project weeks. This shows how painful a setup like this can be, especially when it starts to become a complex robot. Add on top of that the potential for computer intensive algorithms being used on the robot, like route planning or SLAM, and that controller suddenly has a lot to do. My system design separates these jobs out to a selection of individual controllers, such as a system specifically for motor control, or power systems. These controllers can deal with the nitty gritty hardware, and leave the master controller to orchestrate a higher level version of control.

Final Year Project
My design, near the end of the project, with the mecanum wheels, ultrasonic sensors and multiple controllers.

The added benefit of separating out all these jobs means that multiple engineers can work on the same robot, at the same time on different areas and not be worried about breaking the other person’s design. The system specification defines how the modules interact in terms of communication speeds/type, the way to alert other modules and how those communications are scheduled. The master controller (shown in the system block diagram in green) schedules all these communications and decides which modules need specific information. Warnings, control signals and user inputs are all calculated and scheduled, then communicated to and from the required modules. A power system doesn’t care that a user has pressed a button to scroll through an LCD screen, and the master controller means it doesn’t see it.

The above video shows how the robot moves with its mecanum wheels, and how it can easy move around environments. I will explain the more technical parts of the project in a later post, but this simple idea became a very heavy hardware based project, rather than the software project it started as. I learnt about mechanical design, PCB design and good techniques associated with electronic design. For these reasons, the robot won the “Best Project” award for 2017. Thank you to: Cubik Innovation for help with electronic design, and providing PCBs, VEX Robotics for donating the wheels, and Altium Designer for providing their electronic design software. I would not have been able to produce the robot I did without them.

Arianespace Launches a Successful Soyuz

VS18 liftoff
VS18 taking off from the Soyuz Launch Complex (ELS) near Sinnamary.

At 17:10 UTC on the 9th of March 2018, Arianespace launched its second rocket of the year from Guiana Space Center at Kourou. Designated VS18, the Soyuz rocket launched four O3b Satellites into orbit more than 3 years after the last O3b launch. Controlled by a Russian ground crew from the Soyuz Launch Complex (ELS) near Sinnamary, there was a 33 minute delay to the start because of bad weather. The Soyuz used was a Soyuz 2-1b/Fregat placing the satellite in Medium Earth Orbit (MEO).

The VS18 launch from Instagram
The VS18 launch from the Instagram of Arianespace.

A somewhat complex launch, the first ascent lasted 9 minutes and 23 seconds placing the launcher in a sub orbital trajectory. After separation the Fregat performed a 4 minute burn to reach 160 x 205 km x 5.16 deg parking orbit. Coasting for 8 minutes, the Fregat performed its second burn for 8 minutes and 36 seconds to enter  a 190 x 7,869 km x 3.88 deg transfer orbit. Then after a coast of 1 hour and 21 minutes to the apogee, the Fregat fired for its third and final time for 5 minutes and 6 seconds, to enter its 7,830 km x 0.04 deg insertion orbit.

Poster of VS18 launch
Poster advertising the VS18 launch from the Arianespace website.

After the third burn, the satellites were release two at a time, with opposite satellites released at the same time. The first were released 2 hours into launch, and the second set 22 minutes later after a short firing of the Altitude Control System. The rocket then performed 2 more burns to lower its orbit to 200 km below the O3b release point. This was a disposable orbit, intended so that it will not interfere with working satellites.

The four 700kg satellites
The four 700kg satellites being lowered being loaded into the fairing, before the launch. Image from Arianespace website.

The O3b Satellites being prepared to be transported
One of the O3b Satellites being prepared to be transported to the launch site.

The Ka band satellites are the fourth set of O3b to be sent up, making the total constellation 16. Arianespace intend to launch the next set of four in 2019. “The new Ka-band satellites will join the existing O3b constellation to deliver high-speed connectivity to people and businesses in the growing mobility, fixed data and government markets,” Arianespace officials said in a statement. It was reported that the launch was a success, and the Luxembourg based satellite operator SES Networks now have control of the O3b’s.

The fairing of VS18 ready to launch
The fairing of VS18, ready to be attached to the Soyuz rocket, picture from Arianespace website.

The second launch of the year, Arianespace delayed the launch from the original March 6th launch date. This was postponed to conduct extra checks, likely inspired by the partial failure of the Ariane V earlier this year. On January 25th the company lost contact with the upper stage of the rocket. The 3 satellites on board did reach orbit despite the anomaly, but Arianespace have been quiet on the condition of them.

Launch of VS18 with four Ob3
Launch of VS18 with four Ob3 satellites on board. Image from Arianespace website.