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. This lead 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 timeframe, 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.

How Going To The Moon Kick-started the Silicon Age

In the late 1950’s, there were three people who were at the epicenter of a huge breakthrough in the world of electronics, the invention of the Integrated Circuit (IC). Jack Kilby of Texas Instruments, Kurt Lehovec of Sprague Electric Company, and Robert Noyce of Fairchild Semiconductor. In August 1959, Fairchild Semiconductor Director of R&D, Robert Noyce asked Jay Last to begin development on the first Integrated Circuit. They developed a flip-flop with four transistors and five resistors using a modified Direct Coupled Transistor Logic. Named the type “F” Flip-Flop, the die was etched to fit into a round TO-18 packaged, previously used for transistors. Under the name Micrologic, the “F” type was announced to the public in March 1961 via a press conference in New York and a photograph in LIFE magazine. Then in October, 5 new circuits were released, the type “G” gate function, a half adder, and a half shift register.

The Type F flip flop
Junction-isolated version of the type “F” flip-flop. The die were etched to fit into a round TO-18 transistor package
Type F life image
Physically-isolated Micrologic flip-flop compared to a dime from LIFE magazine March 10, 1961

These first few integrated circuits were relatively slow, and only replaced a handful of components, while being sold for many times the price of a discrete transistor. The only applications that could afford the high prices were Aerospace and Military systems. The low power consumption and small size outweighed the price drawbacks, and allowed for new and more complex designs. In 1961, Jack Kilby’s colleague Harvey Craygon built a “molecular electronic computer” as a demonstration for the US Air Force to show that 587 Texas Instruments IC’s could replace 8,500 discrete components (like transistors and resistors) that performed the same function. In 1961, the most significant use of Fairchild Micrologic devices were in the Apollo Guidance Computer (AGC). It was designed by MIT and used 4,000 type “G” three input NOR gates. Over the Apollo project, over 200,000 units were purchased by NASA. The very early versions were $1000 each ($8000 today) but over the years prices fell to $20-$30 each. The AGC was the largest single user of IC’s through 1965.

apollo guidance computer logic module
Apollo logic module assembled by Raytheon to be used in the AGC
Type G micrologic
Philco Ford also produced the Fairchild Type ‘G’ Micrologic gate for the Apollo Guidance Computer – this is the flat pack verison

Note that although Fairchild designed and owned the type “G” device, they were mostly made by Raytheon and Philco Ford under licence from Fairchild. Over this time many semiconductor manufacturers such as Texas Instruments, Raytheon and Philco Ford were also making large scale silicon production for other military equipment. These included the LGM-30 Minuteman ballistic missiles, and a series of chips for space satellites. This major investment from the government and the military kick started the development of the increasingly complex semiconductor, and eventually forced the prices low enough for non military applications. The processes improved and by the end of the Apollo program, hundreds of transistors could be fitted into an IC, and more complex circuits were being made. Eventually the costs of adding more transistors to a circuit got extremely low, with the difficulty being the quality of manufacturing. It could be argued that NASA and the Pentagon paved the way for silicon device production as we know it today.

Luna 1 – The Satellite That Missed the Moon

Luna 1 was the first spacecraft to reach the vicinity of the Moon. Passing just 6000 km away due to an incorrectly timed upper stage, it was meant to impact the moon and spread Soviet pennants to claim the moon as their own. As the satellite ended up in heliocentric orbit, the Soviets renamed it Mechta (Russian for dream), and heralded it as a successful attempt to make a new planet. It was not until years later that Luna 1 was revealed to be a failed plan to impact the mo0n.

A museum replica of luna 1
A museum replica of luna 1

On January 2nd 1959, at 16:41:21 UTC (22.41 local time) Luna 1 was launched from the Scientific-Research Test-Range No. 5 at Tyuratam, Kazakhstan (now named the Baikonur Cosmodrome). Launched aboard Vostok-L 8K72 three-stage launch vehicle, it was the fourth attempt at sending a payload at the moon by the Soviets. The first 3 were:

E-1 No.1 – or Luna 1958A (NASA designation). Launched 23rd September 1958, 07:40. Booster disintegrated 92 seconds into flight due to Excessive vibration. Was the maiden flight of Luna 8K72 Rocket.

E-1 No.2 – or Luna 1958B (NASA designation). Launched 11th October 1958, 21:42. Booster disintegrated 104 seconds into flight due to Excessive vibration.

E-1 No.3 – or Luna 1958C (NASA designation). Launched 4th December 1958, 18:18. 245 seconds into flight, the core stage turboprops lost hydrogen peroxide lubricant, meaning it lost power and impacted downrange.

E-1 No.4 was only a partial failure, and therefore became known as Luna 1. Intended to impact the surface of the moon. Due to an error in timing the upper (third) stage burn time caused a near miss. After 34 hours of flight, at 3.45 UTC on january 4th the probe passed within 5,995km (3,725mi) of the lunar surface, which is about 1 and a half times the moon’s diameter. It was 320,000km from earth, travelling at 2.45km per second. It became the first man-made object to reach the escape velocity of earth. Then after missing the moon it was the first spacecraft to leave geocentric orbit and enter heliocentric orbit.

A replica of the luna 1 attached to the cone
A replica of the luna 1 attached to the cone

The Luna 1 module was hermetically sealed sphere weighing 361.3kg (795.9lb) with 5 antennae extended from one hemisphere; four whip antennas and one rigid antenna. The spacecraft contained a 19.993 MHz system which transmitted signals 50.9s long, a 183.6MHz transmitter for tracking purposes, and a 70.2MHz transmitter. The batteries on board were mercury-oxide and silver-zinc accumulators. Five sets of scientific equipment were externally mounted to the unit to study the journey including a geiger counter, scintillation counter, and micrometeorite detector, along with a Sodium experiment. The device on the end of the center rod protruding out the back is a magnetometer to measure the moon’s magnetic field.

The primary objectives of the mission were to:

  • Measure the temperature and pressure inside the vehicle.
  • Study the gas components of interplanetary matter and corpuscular radiation of the sun.
  • Measure the magnetic fields of the earth and the moon.
  • Study meteoric particles in space.
  • Study the distribution of heavy nuclear nuclei in primary cosmic radiation.
  • Study other properties of cosmic rays.
    Another schematic of Luna 1
A schematic of the Luna 1
A schematic of the Luna 1, unfortunately with russian annotations

at 00:56:20 UTC on january 3rd, 119,500km (74,300mi) from earth, the spacecraft released 1kg (2.2lb) of sodium gas. This formed a cloud behind it to serve as an artificial comet. The glowing orange trail of gas was visible over the ocean with the brightness of a sixth-magnitude star.  Mstislav Gnevyshev at the Mountain Station of the Main Astronomical Observatory of the Academy of Sciences of the USSR near Kislovodsk took a photograph. This was designed as an experiment on the behaviour of gas in outer space, as well as functioning as a navigational aid helping ground control track the mission.

gas cloud of sulphur
Gas cloud photographed by Mstislav Gnevyshev at the Mountain Station of the Main Astronomical Observatory of the Academy of Sciences of the USSR near Kislovodsk

Luna 1 was made of an aluminium-magnesium alloy and sealed with a special rubber. To protect the satellite there was a cone to take the heat when passing through the dense layers of the atmosphere. When safely out of the atmosphere the cone was discarded, and the antennae unfolded. On the same half as the antennas were two proton traps to find the gas components of interplanetary matter, and two piezoelectric pickups to study meteoric particles. The inside of the unit was filled with gas at 1.3 atmospheres, to ensure high pressurisation inside. Through the design, the high pressure allows for an air circulation within the unit. This circulation drew heat off equipment and instruments, transferring it to the shell, that then serves as a radiator.

The nose cone
A replica of the nose cone in an exhibition in 1969
How it fitted
A diagram showing how the nose and luna probe fitted

The Vostok-L 8K72 was a modified R-7 Semyorka intercontinental ballistic missile.The R-7 rocket was designed by Sergei Pavlovich Korolev, known more commonly as the Chief Designer. The 8K72 version consisted of two core stages with four external boosters. The first stage and each of the boosters were powered by a four-nozzle RD-107 rocket engine burning kerosene and liquid oxygen. Total thrust was approximately 1,100,775 pounds (4,896.49 kilonewtons). The second stage used a RD-0105 engine, producing 11,015 pounds of thrust (48.997 kilonewtons). The Luna 1 was propelled by a third stage which remained attached during the translunar coast phase of flight.

Vostok on Takeoff
Vostok on takeoff with the luna 1 on board

After Luna 1 passed the moon and continued on towards heliocentric orbit, it only had a certain amount of battery power left. Because it was meant to collide with the moon it had no need for recharging. On january 5th at approximately 07:00 the radio transmitter ceased to operate at a distance of 600,000km from earth. It is still in an orbit around the sun, somewhere between mars and earth. It completes one rotation in roughly 450 days. for those who understand the terms associated with orbital mechanics here are the numbers:

  • Semi major Axis: 1.146AU
  • Eccentricity: 0.14767
  • Perihelion: 0.9766AU
  • Apohelion: 1.315AU
  • inclination: 0.01 degrees
Luna1 Trajectory
Luna 1 Trajectory

The main aim of the mission was to hit the moon, the reason was to plant 2 Soviet pennants onto the moon. They were highly durable, made from titanium with thermoresistant polysiloxane enamals, that could reportedly survive an impact with venus. Usually a few are minted to give to VIP’s and top scientists. For them, it’s similar to planting a flag. one of the pennants on this flight was a thin metal strip with the inscription “Union of Soviet Socialist Republics” on one side and the coat of arms of the Soviet Union and the inscription “January 1959 January” on the other. The other pennant was spherical, symbolising the moon, each face has the inscription “USSR, January 1959,” on one side and the coat of arms of the Soviet Union and the inscription “USSR” on the other. These pennants were eventually distributed on the moon by Luna 2.

luna 1 pennant 1

Luna 1 pennant 2
The pennants on the Luna 1, that are still inside the satellite to this day.


The Abandoned Buran Launch Site

So on my recent search for history on the Buran Shuttle, I came across this blog post. Although I had to use the Wayback machine to see it, it shows some great shots of the place where the Buran Shuttle used to launch.



The images show the way that the test site has been left to rust away. Although still obviously a launch site, the stone is breaking, and the machines obviously havn’t been used in a long time.


As you can see, there is still rubbish piled up, remains of old vehicles, and random scrap metal everywhere. Almost like everyone just up and left. If you have read any of my other posts on the Buran, you will know that is basically what happened. Around 1993, the USSR crumbled and the Buran shuttle programme was left behind. This is why this launch site is still like this, and why urban explorers can go out and take pictures.

On top of this, they found a few other things, including an actual Buran shuttle. Although not a working version, more of a prototype, this shuttle shows how it probably would have looked back in the day. I believe this is the version found at the Gagarin museum in the Baikonur Cosmodrome, close to the launch site found in these pictures. This one is on display to the public, and was refurbished in 2007.


The last thing that they found was a large machine. More specifically, the machine used to transport the Shuttle to the launch site. A colossal platform, that could move the shuttle and the solid rocket boosters needed for the flight. Unfortunately it was only ever used once in 1988, the only BUran flight ever. So it hasn’t seen much action. It was different to the USA’s Crawler-transporter because it was pulled by 5 diesel trains.



The Abandoned Buran Wind Tunnel Test


40km Southeast of Moscow in the back corner of Zhukovsky International Airport, there is an an interesting remnant of the space race just left to rot. These are a set of 15 pictures taken by Aleksander Markin on this Flickr album. It shows a 1/3rd scale model of the Buran Orbiter. According to Markin, the replica is made almost entirely out of wood, and was used as a wind tunnel test when developing the aerodynamics.

airfield-6 airfield-1airfield-9 airfield-8airfield-10 airfield-13 airfield-12 airfield-11airfield-14 airfield-15 airfield-2 airfield-5 airfield-4 airfield-3

When the Buran shuttle program fell into disarray, after the collapse of the Soviet Union, these prototypes and test were just left behind in the change. In the intervening years, they have been left the rot. Many shuttles and tests have been found by urban explorers, but many are still out there. In another recent post I talk about a similar Buran prototype left to rot away in an impressive warehouse. You can find that post here.