Read any book about the United States Air Force during the cold war and you will probably find a section about the secret fleet of soviet fighter jets that they kept, tested and stole technology from. The less known part is that the Soviets also captured US planes during conflicts, although it seems like less overall. This is the story of the F5 that ended up deep in Russia.
It wasn’t actually the Russians that captured the plane in the first place, it was the Vietnamese. At the end of the Vietnam war, there were many captured parts of american military equipment in different forms. Vietnam, a famously communist country gave several samples of captured US aviation equipment to the USSR, among it was a F-5E light fighter bomber. Overall 27 were captured during the war, along with 87 F-5A’s. Overall 877 aircraft were captured. The Vietnamese actually plan to bring some back into service. The particular F-5E had serial number 73-00807, and was an extremely valuable intelligence coup that had the ability to tell the communists about American design, and how this form of mass produced plane could function. Therefore how they could design planes to counter it.
The plane was sent to the VVS airbase in Chkalovsky before being transferred to the Akhtubinsk air base not long after. Engineers and research staff from the Aeronautical research institute were formed as a test team to investigate the American fighter jet and test its abilities. Overall they were impressed with the design of the jet, and admired the ease of maintenance on the F-5E while they operated it. They were also impressed with the wing design, as t gave the jet an impressive flying ability at high angles of attack and minimum speeds. The F-5E was known officially as the Tiger II. From the end of July 1976 to May 1977, a full scale test flight was conducted at the Air Force Research Institute. A.S.Byezhyevets and V.N. Kondaurov, both decorated Heroes of the Soviet Union, were the pilots in charge of the test flight.
They were surprised with the results, the F-5E was much more maneuverable than most Soviet aircraft, especially then the MiG-21, which was the highly capable soviet dog fighter of the time. It even showed some advantages over the MiG-23, the most advanced Russian fighter of the time. That being said, it was noted that the F-5E did have a disadvantage when it came to vertical maneuverability and energy when compared to the MiG-23. It also had a lacking arsenal, with nothing beyond visual range medium-range missiles, which the MiG-23 could hold. The Central Aerohydrodynamic Institute (TsAGI) in Moscow were in charge of static tests of the aircraft, with the results exhaustively recorded. It is interesting when you look at planes such as the T-8 and the T-10, as you can see some design features obviously lifted from the F-5E. Eventually it was moved in the 1990’s, or at least the nose was, to a display area known as Hangar 1, which is now virtually impossible for any outsiders to visit.
Thank you for reading, take a look at my other posts if you are interested in space, electronics, physics or military history. If you are interested, follow me on Twitter to get updates on projects I am currently working on.
A recent report funded and published by the United Launch Alliance outlines the the potential viability of mining the Moon for rocket fuel. At over 170 pages, it is quite a read but Philip Metzger, one of the authors wrote a good summary on his website. I thought I would try and make a similar summary here with slight more explanation, and where it fits into the future NASA plans of getting back to the Moon and going onward to Mars and beyond. It all revolves around water, or more specifically ice. For many years we thought the Moon was a baron rocky cold desert. The samples that the Apollo astronauts brought back from the Moon, and the Soviet Luna samples imply that there is no water in the rocks or regolith. The trace amounts of water found in the samples were assumed to be contamination. Although, in 2008, a study of the Apollo rock samples did show some water molecules trapped in volcanic glass beads. Also in 1978, Soviet scientists published a paper claiming the 1976 Luna 24 probe contained 0.1% water by mass. Plus the Apollo 14 ALSEP Suprathermal Ion Detector Experiment (SIDE) detected the first direct evidence of water vapor ions on March 7th 1971. None of these discoveries were taken as conclusive proof of water on the Moon at the time.
On September 24th 2009 it was reported that the Moon Mineralogy Mapper (M3) spectrometer on India’s Chandrayaan-1 spacecraft had detected water ice on the Moon. The map of the features show that there is more at cooler, higher latitudes, and in some deep craters. Basically, the parts of the Moon that see the least light like the poles and far into craters near the poles have managed to keep the water on and below the surface. This water is in a number of different states, some locked up in minerals, some in ice form, and others in OH form, not technically water but near. This has lead to a number of new possibilities of inhabiting the Moon and using its resources. This is why the United Launch Alliance funded a paper on the possible use of mining this water and using it as a future fuel source. By some estimates there could be as much as 10 billion tonnes of water on the Moon. The water could in theory be mined, and through electrolysis turned into hydrogen and oxygen, the fuel that got men to the Moon on the famous Saturn V.
But you have to ask, why does it matter? the Moon is far away, and surely water is just useful for astronauts living on the Moon to survive. Well the report talks about the business case to use the water as fuel, in the form of hydrogen and oxygen. First we need to understand the commercial satellite world, and geostationary satellites. When first sending up such satellites, the way to do it was to use a multi stage rocket, with the first stage getting to a Geostationary Transfer Orbit (GTO) and then the second (upper) stage being used to get into the Geostationary Orbit (GEO). Recent years have allowed the first stage to be hugely improved and often reusable by companies like SpaceX and Blue Origin. The second stage hasn’t had the same improvements though. Traditionally the second stage was a normal, and very heavy liquid rocket. This meant that it was very expensive to get things to GTO, much more difficult than LEO. The rocket was also thrown away afterwards, and as it is so far out it will take hundreds or even thousands of years to burn up in the atmosphere.
Now we do have a better way to do it, sort of. I talked recently about the rise of electric thrusters. A lightweight, cheap and powerful solution when used over a long period of time. Over the time span of years they can pick up speeds of thousands of miles per hour. That is the biggest downside of them though, in this situation, slowly pushing the satellite to orbit, they take up to a year to get a satellite into position. That is a year that it could be making the owner money. By some estimates that year could lose $100 million in revenue just waiting for the slow thrusters. By all accounts though, this is still cheaper than launching a large traditional rocket upper stage. The electric thrusters are amazingly light comparatively, which means you need a smaller first stage to get it up to space in the first place. The key thing you have to remember about these geosynchronous satellites is that they already have a huge price tag, some can cost upwards of half a billion dollars to build and launch.Part of the reason is that they tend to be huge, in size and weight. Some have been as big as London double Decker buses, and weigh 6 tonnes. The rockets then need to get them to one of the furthest and time consuming orbits, a costly exercise.
So why can this Moon mining idea help? well the Moon is in lots of countries space plans at the moment. China are currently sending lots of probes, and by some accounts looking to get humans there. The USA are building the SLS which should be able to get humans to the Moon, and are also developing the LOP-G idea. The concept to have an orbital station around the Moon, almost like a fuel stop for rockets going on to further parts of the solar system. This idea to mine the Moon for hydrogen and oxygen could be transferred up to this orbital space station to be transferred to the rockets that need it. This is where the geosynchronous satellites come in. Imagine if this fuel, that is dug up and processed by robots, and then sent up to an orbital station could be brought back closer to Earth via a space tug. This space tug could meet up with the rocket with the satellite on board. The upper stage rocket could have been sent up with no fuel (the heaviest bit) and is fueled by this space tug. It would allow for the speed of the old style engines, but the weight of newer electric engines. As long as the price for this whole system is cheaper than the $100 million it currently costs, then it could be a viable option. All the while, setting ground work for space agency’s to have viable water sources that can be used for future exploration. It may be the future of space travel.
Thank You for reading, take a look at my other posts if you are interested in space or electronics, or follow me on Twitter to get updates on projects I am currently working on.
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.
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.
My remote cameras worked well, & I’m happy with the long exposure I got…but capturing the @SpaceX#Falcon9 going through the supersonic regime leaving these iridescent vapor rings at an altitude of 11km is my favorite🚀 @elonmusk
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.
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.
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.
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.
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.
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.
Salton Sea Naval Base is not known as one of the famous military test sites in the United states. Although it isn’t as revered as places like White Sands or Edwards AFB it is still the location of some of the most important testing during the second world war. It aided in the development of the Fat Man, the bomb that eventually ended the second world war by destroying Hiroshima and Nagasaki in Japan. With many aerodynamic testing, and target practice for the bombers, at one point it was one of the most secret places in the United States, now it is basically a desert, with broken buildings, occasionally being found by urban explorers.
Salton Sea is a shallow saline lake located directly on the San Andreas Fault. The U.S. Navy inspected the site in January of 1940, and commissioned it as the Salton Sea Naval Auxiliary Air Station in October 1942. The base was designed as a training base for seaplanes, and was located just to the south east of Salton city. Although it only initially took claim of the northern end of the Lake, it eventually controlled part of the southern end too. Technically speaking it is a Naval Station and not a Navy Base, but most references refer to it as a Test Base.
Throughout the 1940’s it functioned as an active military weapons test site. Lt. Col. Paul Tibbets led the 393rd Heavy Bombardment Squadron during 1944 and 1945 through a series of classified B-29 practice flights from Wendover, Utah to the Salton Sea, where they would drop dummy atomic bombs onto a floating white raft. This was used as the testing site for the fateful atomic weapons attacks that ended the second world war for Japan. It is said that Tibbets dropped the first atomic bomb himself on Hiroshima in a plane named after his mum, Enola Gay. The prototypes were tested at Salton Sea.
The crews made hundreds of practice runs over the Mojave and Salton Sea. The bombs they used were full size mock-ups, sometimes filled with concrete, other times containing everything except the nuclear part. This often meant being filled with explosives. During one Salton Sea run, an engineer dropped one of the Fat Man mock ups too soon. It narrowly missed the town of Calipatria. The bomb buried itself 3m into the ground, but luckily didn’t explode. Bulldozers rushed to the scene to erase the evidence.
During the 1950’s the base was used by Sandia National Labs as a range for missile testing, with over 1,100 missile tests being conducted there. Sandia was the principal contractor for the Atomic Energy Commission after the war, and they renamed the site Salton Sea Test Base in 1946. They used the site to test weapons, space capsule parachute drops, drone airplane tests, and Nike missile launches. 150 different tests were conducted annually over a ten year period some using depleted uranium. Sandia ended operations in 1961 when they moved to a new remote site. The main reason for moving was a fight with rising waters of the lake.
During the 1960’s it was mainly abandoned, and in the 1970’s it was occasionally used for live munitions practice. Most buildings suffered substantial damage. The site was listed as inactive in 1986, but the facility found renewed life as a site for Gulf War training maneuvers during the 1990’s. As most of the original buildings were destroyed, the base was decommissioned and turned over the the U.S. Bureau of Reclamation in the mid-1990’s. The Site was used during the early 2000’s as a research site for salinity control. There are no plaques or monuments to the achievements of Salton Sea, and the parts it played in winning the second world war, and very little online about it.
Thank You for reading, take a look at my other posts if you are interested in space or electronics, or follow me on Twitter to get updates on projects I am currently working on.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
On April 18th, 2018 at 22:51 UTC a Falcon 9 took off from Launch Complex 40 at Cape Canaveral AFB. Aboard was NASA’s latest research satellite TESS. A mission that cost $337 million, Transiting Exoplanet Survey Satellite (TESS) is the latest in a line of space based observatories that are set to launch this decade. Launched into an arching elliptical orbit that will take the spacecraft over two thirds of the distance to the moon. The first stage of the Falcon 9 landed on the autonomous drone ship Of Course I Still Love You to be refurbished and reused.
After a 5 day checkout of the spacecraft, basically a hardware check, the ground controllers will switch on the TESS cameras. TESS is designed to scan around 85% of the sky during the two year mission, with astronomers estimating as many as 20,000 new planets could be found. It plans to build on discoveries made by NASA’s Kepler telescope which was launched in 2009 to find earth like planets. TESS carries four 16.8-megapixel cameras, and will look for dips in light coming from 200,000 preselected nearby stars. The four cameras cover a square in the sky that measures 24 x 24 degrees, wide enough to fit the Orion constellation into a single camera. the cameras together study a set area of sky for 27 days before staring at the next section.
The orbit TESS is being launched into is known as P/2, and requires time and finesse to reach. TESS will slingshot by the moon at a distance of around 5,000 miles (8,000 kilometers), using gravity to reshape its orbit, increasing the satellite’s orbital perigee, or low point, to the final planned altitude of around 67,000 miles. After the lunar flyby, the high point of the satellite’s elongated orbit will stretch well beyond the moon, and another thruster firing will nudge TESS into its final orbit in mid-June. Science data is planned to start in july, with the first year of the two year campaign aimed at the stars in the southern sky. TESS has been built to have enough fuel to last 20 or 30 years, assuming funding by NASA and the components on board continue to function correctly.
Each of TESS’s cameras have four custom built re-sensitive CCD sensors designed and developed by MIT’s Lincoln Laboratory. The sensors are claimed to be the most perfect CCD’s ever flown by a science mission. The lenses used by the cameras are only about 4 inches (10mm) wide, meaning it has a fairly low light collecting power compared to other space telescopes. The James Webb Space Telescope for example launching in 2020 had a 21.3ft (6.5m) primary mirror, although the satellite has cost over $8 billion to make. TESS is a bit like a finder telescope, it will lay a bedrock for future missions such as Webb and ground based observatories to make better readings. It gives a good idea of the best places to look, where the most likely exoplanets are.
TESS works by looking at a star, in this case mainly M-dwarf stars, which are cooler than our sun. They are also known as red dwarfs and make up most of the stars in our galaxy. When a planet goes in front of the star the light received by TESS “dips” and changes slightly in colour. This change in the light it receives can tell scientists alot about the size of a planet, and other things like density and velocity. They expect TESS to find between 500 and 1,000 planets that are between one and three times the size of Earth, and 20,000 planets the size of Neptune or Jupiter. The readings will give a good idea of where to focus on and ‘follow up’ on future missions. Then missions such as JWST can probe and use more complex tools to find information such as atmospheric composition, and whether they could be habitable.
The Falcon 9 used was a v1.2 with designation F9-54. It used a brand new “Block 4” first stage. The booster designated B1045 has a clear 45 written on the side in some of the close up booster images. The fist stage boosted for 2 minutes and 29 seconds, then detaching and slowing itself down. The booster landed downrange on the autonomous drone ship “Of Course I Still Love You”. The first successful drone ship landing since October 2017. A total of 24 Falcon 9 or Falcon Heavy booster stages have now been recovered in 30 attempts. Four of which were on “Just Read The Instructions” off the coast of California, ten at Cape Canaveral Landing Zone 1 and 2, and nine on the autonomous drone ship “Of Course I Still Love You” off the Florida Coast. 18 first stages have been recovered, 11 of which have flown twice, five have been lost during their second flight. B1045 was the last brand new “Block 4” Falcon 9 booster.
In a previous post I talked about how the going to the moon kick started the silicon age. If you haven’t read it, it is short but really interesting story about how NASA made Integrated circuits cheap, and partially funded what we now know as Silicon Valley. In this post I am going to take a slightly closer look at the circuit that ran the famous type “G” Micrologic gate that ran the Apollo Guidance Computer.
As you can see in the above image, the circuit was not particularly complicated. You have to remember that this is very early logic, before CMOS or NMOS or any other fancy IC technologies. This is basically two 3 input NOR gates, they both run off the same power, with pin 10 at the top, and the negative which was likely ground being shared on pin 5. The output for the left NOR gate is pin 1, and the output for the right is pin 9. The three inputs for the left are pins 4, 2 and 3, with the right having pins 6, 7, and 8 as inputs. Simply put, the output is “pulled” high to power when all the inputs are OFF. The resistor between pin 10 and pin 1 (or 10 and 9) are a simple pull up resistor as you would find in most electronic circuits. As expected with a NOR gate, the output will be only be ON when all the inputs are OFF. When any of the inputs are ON the output of that gate will be pulled to ground. One two, or all the inputs can be on, but it just needs one to turn OFF the output. The resistors going into the base of the transistor are just to limit the current.
I made a simple recreation of this circuit using BC547 NPN transistors, but most NPN transistors would work, these were ones I found in my parts box. As you can see in the image above, I have made it on a breadboard, with the inputs being a DIP switch attached to the power (5V in this case). The base resistors for the transistors are 1K and the pull-up to 5V is a 10K. I recommend making up this circuit if you want to learn a bit more about logic, and is a cheaper method than going out to buy 74 series logic chips! As you can see in the images there are a number of states that I showed the circuit in, and notice that if any of the switches are on, the circuit turns on, this is slightly against what I mentioned earlier, but thats due to the output LED using the transistor as a current sink, not a source, so the output is inverted. Basically, when the output is 0 the LED turns on. The only time the LED is off (output high) is when no switches are on, meaning all the transistors are off.
The final point for this post is why the circuit is actually quite inefficient. Modern logic is amazingly low power compared to this. One of the biggest issues is that it is always taking power in some way. When the inputs are off, there is still some leakage through the pull up resistor, when an input is on, then there is current going through the resistor to ground. Also, by the nature of the transistors there is always parasitic leakages, and inefficiencies in the process. They are only small numbers, but the AGC used over 3000 of these circuits, so the small leakages soon add up to draw some hefty power needs, especially for battery powered operations.
If you enjoyed this post, take a look at the rest of my blog, there is lots about space, electronics and random history. I am always open to ideas and feedback, and where is best to post links to my posts.
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.
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.
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.
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.
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.
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?”.
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.
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.