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

How the Type G Gate Worked

apollo 3 input NOR gate
An image of the silicon die inside the Type G 3 input NOR gate used to power the Apollo Guidance computer.

Previously I went through the three input NOR gate that ran the Apollo Guidance Computer and how the circuit works. Previous to that I also told the story of how this chip partially funded Silicon Valley as we know it today. This post builds on that and goes through how the silicon works, and the simplicity of the circuit. Quite a famous image of the chip, fairly detailed image of the silicon inside the device spurred on this post, and taught me lots about silicon that I want to pass on.

apollo 3 input NOR gate schem annotated
The schematic of the 3 input NOR gate. From the schematic of the Apollo Guidance Computer. Annotated with my own designators for reference.

The above schematic of the 3 input NOR gate is also shown in previous posts. It is from the NASA Apollo Guidance Computer schematic, but I have annotated it so that I can reference to specific parts. It is a handy schematic considering it was right at the start of the development of semiconductors. The first image in the post is the best image of the silicon, but is not very big. The biggest image I can find is not quite as sharp, but is much better to annotate, it is the same chip. The first annotation shows the pinout of the device, and how those pins actually connect to the pins.

apollo 3 input NOR pin out
The silicon of the 3 input NOR gate with annotations to show which pin is connected. The pin numbers are from the schematic.
Showing how pins are connected
An image showing how the pins coming off of the silicon are connected into pins of the flat pack.

The noted parts of the above images are pins 5 and 10, and are the starting points to deciphering the layout. If you look at pin 5 and 10 on the schematic, they correspond to GND and power respectively. They are the only pins that are shared between both NOR gates. Apart from that the two sides look remarkably similar, and are basically a mirrored version. To figure which is ground and which is power, the resistors need to be taken into account.

apollo 3 input NOR gate resistors
The resistors on the silicon of the device. Shown above as brown lines they are P doped silicon that act like a resistor.

The above image shows the resistors found on the device. They tend to just be a thin section of P doped silicon, and above connect two sections of aluminum to form a resistor. It is also noted that there is big section of brown surrounding the whole circuit. Although it functions like a resistor and is made in the same way, it is puterly for ESD purposes, protecting the circuit. This big ring also is a big hint that it is connected to ground (pin 5). the second hint is that GND has no resistors attached to it on the schematic, but power has two. They are R1 and R2, connecting to pin 9 and 1 respectively, and are pull up resistors. Pin R3 to R8 are simply the base resistors for the transistors. They are all roughly the same size, and are there are 6 of them. The transistors are also fairly obvious in the centre of the silicon.

apollo NOR gate transistors
The centre silicon from the Apollo 3 input NOR gate. The transistors have been shown, and the collector, base and emitter also shown,

The above image is showing the heart of the device. the 6 transistors that make it resistor-transistor logic. As you can see in the above image, all the collectors are connected together, connected to pins 1 and 9. If you look closely, the base and emitter of each transistor sit inside a brown section like the resistors. This is P doped silicon and forms the base-emitter junction. This allows the base and emitter to sit anywhere within that P doped silicon detection to work. This means that the transistors do not conform to the standard Collector-base-emitter topology. All of the emitters are also connected together via the aluminium placed on the top, but the P doped sections of each device are seperate. As all the transistors of each device have common emitters, it doesn’t matter that they are all connected together, by design, only one of the transistors needs to be on for it to function.

Ken Shirriff transistor side view
A great image showing how the transistor works from a side view by Ken Shirriff.

The above image found on Ken Shirriff’s blog shows how the transistor works with the emitter and base in the P doped silicon. I may do some more posts about it, but his blog is a great place to find more information on silicon reverse engineering.

Electronics world 1963
A cutout from electronics world in 1963 showing the new process of planar technology. This method was used to make the NOR gate.

The above image is an interesting one I found while researching this chip. A section in electronics world 1963 showing how micrologic is made. The type G chip was part of the second batch of micrologic circuits. This section was useful to see how silicon was actually manufactured, and in some ways, still is today.

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

Atlas V Launches InSight

Atlas V on the pad
The Atlas V on the launch pad at vandenberg AFB in California, Credit: ULA flickr.

At 11:05 UTC on May 5th 2018 the forth Atlas launch of the year launched the long awaited InSight mission on a course for mars. Launching from Vandenberg Air Force Base the AV-078 (the launch designation) was an Atlas V in 401 configuration. It was the first interplanetary launch from the west coast of the United States. Liftoff of the Atlas V with a 4m payload fairing was from Space Launch Complex 3 East.

Sam Suns first tweet
An awesome photo of the launch that blew up on twitter, taken from the sky. Credit @BirdsNSpace on Twitter.

The rocket had one main payload, the InSight Mission and two CubeSats. InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a robotic lander designed to study the interior of the planet Mars.  I weighed 694 kg at launch, including a 425 kg fueled lander. The lander carries a probe that will be hammered 15m into the Mars surface, a seismometer, a magnetometer (first expected to land on the surface of Mars), a laser reflector, along with other instruments. The lander also has a robotic arm to move payloads around, but there will be another post in the future discussing the instruments in more detail. The two CubeSats on board are known as MarCO-A and MarCO-B, each weighing about 13.5 kg. They will fly by Mars while conducting a data relay experiment with InSight.

Insight Fairing
The 4m payload fairing on top of the Atlas V containing the InSight payload. Credit: ULA Flickr.

The design of InSight was developed from the 2008 Phoenix Mars Lander. The previous lander was launched on Delta 2 rockets compared to the Atlas V, both built and launched by the United Launch Alliance. The Atlas V does have excess capability for the mission (slightly overkill) but this allowed it to be launched from Vandenberg AFB. Previous solar orbit missions (like this one) were launched from the Cape to gain the site’s eastward earth rotational velocity. Vandenberg launches have to fly south or westerly direction across the Pacific Ocean. InSight was originally planned to launch in 2016 but was delayed to 2018 due to the main instrument failing.

Liftoff od Insight
The Atlas V lifts off, unfortunately the fog rolled in so very few great shots were taken by the remote cameras. Credit: ULA Flickr.

AV-078 started on a 158 degree azimuth, aiming towards a 63.4 degree Low Earth Parking Orbit. The LOX/RP-1 fueled RD-180 powered first stage fired for 4 minutes and 4 seconds. The Centaur’s RL10C-1 LOX/LH2 engine then fired for 8 minutes and 48 seconds to reach the parking orbit. It then coasted for 65 minutes and 40 seconds then performing a second, 5 minute and 23 second burn to accelerate into a trans-Mars solar orbit. Insight separated 9 minutes after at about T+1 hour, 33 minutes and 19 seconds. The CubeSats separated shortly after.

Aaron Colier Atlas V launch
An awesome long exposure shot of the launch taken by Aaron Collier. From roughly 85 miles away. Credit @aaroncollier96 on Twitter.

What We Learnt From The Peter Beck AMA

Peter Beck is the CEO and founder of Rocket Lab, a US/New Zealand orbital launch provider who is trying to provide access to space for small satellites. On at 19:00 UTC on April 5th he participated in a Reddit AMA on /r/space, where he answered as many questions as he could about the Electron launch vehicle and the upcoming ‘it’s business time’ launch, as well as what the future of space access looks like. It was a good AMA, he answered lots of questions, and the full post can be found here. This post is to round up some of the most common and important questions he got asked for those interested.

Peter Beck by Electron
Peter Beck, president of Rocket Lab in front of the Electron launcher. Credit: Rocket Lab

The most questions came with reference to SpaceX, and the way their business model compares to Rocket Lab.

SpaceX didn’t see a market It’s known that the Falcon 1 was a similar size to the Electron and they quickly moved on from it. So people asked if SpaceX didn’t stay with it, why will it work for Rocket Lab?  Peter makes the point that SpaceX retired that rocket 10 years ago, and most of Rocket Labs customers didn’t even exist then. He mentioned that Electrons manifest is fully booked for the next 2 years for dedicated flights. He also doesn’t see a slowdown in demand anytime soon.

Reusability – On the SpaceX front, they have made big inroads to reusability and the Electron is not reusable, so many asked about plans to make a reusable version. The simple answer he gave was that reusability makes sense for medium lift vehicles like the falcon 9, but it doesn’t scale well to small vehicles. So it isn’t on the radar for them at the moment.

Electron Launch Vehicle
Rocket Lab’s first Electron rocket, seen here in a hangar at the company’s New Zealand launch site. Credit: Rocket Lab

Other Rocket Manufacturers – As there are many small rocket manufacturers popping up, and attempting to compete in this space, many wanted to know what the market is actually like for them. His comment was that not all of those manufacturers will make it, and they are currently the only dedicated small launcher that has actually made it to orbit. Others were quick to point out that other rockets of similar size do launch but nowhere near as frequently and do not have the same quality or launch frequency as the Electron.

Where else will they launch from – Currently they have a single launch site, but many wanted to know if they will branch out, to different pads of even different countries, maybe even pad-39A. He mentions that he wants to have many potential launch pads to serve many different inclinations, but Launch Complex 1 is a good start.

Going Bigger – There were lots of questions about making a bigger rocket, like an Electron Heavy. He made a point of saying they are currently only making one product really well. They have no plans to make bigger rockets, and they understand the market they are in. Rocket lab do not want to compete with SpaceX on these launches. He mentions that they can launch a huge amount of spacecraft to LEO, and going bigger only allows a 2% increase in market at the moment. That being said they will continue improving the rocket as they go along.

electron on the pad
The Electron launch vehicle waiting on the pad for takeoff, Credit: Rocket Lab

Using composites – As the LOX tank and other parts are made of carbon composites, there were questions about the difficulty surrounding the design and development of that. He talked about the several years developing and testing the composite tanks. The two main issues being microcracking and oxygen compatibility. They ended up with liner-less tanks with common bulkheads that have similar oxygen compatibility to aluminium but much lighter mass. All the composite manufacturing is in house. Some wanted to know how they manage to use such expensive processes, and he says that although carbon fibre is expensive, when done right you can use very little of it.

Why black – with most rockets out there being white, to help with the thermal efficiency, why did they go for black? Well the simple answer he gave was it looks better. Many engineers wanted to paint it, but the thermal experts made a special effort to make sure they could keep it black. Also, it does save some time/money/weight on paint.

It’s all about the money – The key question is, is it profitable, and when will they start making those profits? Well Peter states that they will see positive cash flow after their 5th flight. Each launch costs $4.9 million to each customer, and they get a dedicated launch, so no need to worry about rideshares where they have less control.

Electron Launch
Electron Rocket takes off from Rocket Lab Launch Complex 1 during the “Still Testing” mission. Credit: Rocket Lab

Adding to space junk – In the news recently, there has been lots of the junk that currently floats in space, so there were some questions on how the Electron tries to stop being just more rubbish. Peter talks about the Curie stage of the rocket that is designed to fix this issue. It puts it the second stage into an orbit that makes it deorbit quickly, and the kick stage can deorbit itself. Also most of the LEO payloads they will orbit will deorbit within 5-7 years.

Launch cadence – A few asked how often they are able to launch rockets, or at least the plans to do so. He mentioned that the current plan is to launch once a month for the next year, then once every two weeks, and then double down from there. The Launch complex 1 can support a launch every 72 hours, which is pretty impressive.

Job opportunities – As you would expect, many people asked how you get a job/internship at Rocket Lab. Peter gave a link to email a resume to, but mentioned that the bar is high, they are open to new people but they have to be passionate, and enjoy (and be good at) what they do. They are a small team trying to do big things! They care about what you do outside your formal education, what are you passionate about? what have you built, tested and broken?

Rocket testing
Rocket Lab testing its engines for the Electron launch vehicle. Credit: Rocket Lab

Some hardcore technical answers

  • Each propellant had a dedicated and independent pump system rather than a single electric motor.  That was due to wanting super accurate control over the oxygen fuel ratio and startup and shutdown transients.
  • Ignition is from an augmented spark igniter (a spark plug surrounded by a tube, what acts sort of like a blowtorch).
  • The engine is fully regeneratively cooled, 3D printed chamber.
  • The area ratios for the booster and vacuum nozzles are 14 and 100 respectively.
  • The steering and ullage on the upper stage is controlled by cold gas RCS and PMD.
  • The whole vehicle is non pyro, the decouplers are all pneumatic.

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.

When Planes Need an Eye Test

Naval Outlying Field Webster
The photo resolution marker at Naval Outlying Field Webster, From Google Maps

A few years ago, The Center for Land Use Interpretation (CLUI) reported on the dozens of Photo calibration targets found in the USA. They are odd looking two dimensional targets with lots of lines on the of various sizes, used as part of the development of aerial photography. Mostly built in the 1950’s and 60’s as part of the US effort of the cold war.

Shaw Air Force Base
The photo resolution marker at Shaw Air Force Base. From Google Maps

At this point, just after the second world war, there was a huge push to get better information about the enemy. The military needed better aerial recconasance. This very problem lead to the development of the U-2 and the SR-71. As part of this, there needed to be methods of testing these planes with the big camera systems attached to them. This was before the development of digital photography, so resolution is much more difficult to test.

The USAF test target
The 1951 USAF test target from wikipedia, they can still be bought.
Fort Huachuca
The photo resolution marker at Fort Huachuca. From Google Maps

This is where the photo resolution markers came in. Much like an optometrist uses an eye chart, military aerial cameras used these giant markers. Defined in milspec MIL-STD-150A, they are generally 78ft x 53ft concrete or asphalt rectangles, with heavy black and white paint. The bars on it are sometimes called a tri-bar array, but they can come in all forms, such as white circles, squares, and checkered patterns.

Beaufort Marine Corps Base
The photo resolution marker at Beaufort Marine Corps Base. From Google Maps

The largest concentration of resolution targets is in the Mojave desert, around Edwards Air Force Base. This is the place most new planes were tested during this time, with the U-S, SR-71 and X-15 being just some of the planes tested there. There are a set of 15 targets over 20 miles, known as photo resolution road. There are also plenty of other resolution targets at aerial reconnaissance bases across the US, such as Travis AFB, Beaufort Marine Corps Base and Shaw Air Force Base.

Elgin Air Force Base
The photo resolution marker at Elgin Air Force Base. From Google Maps

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.