TEPCs aboard the ISS

A Tissue Equivalent Proportional Counter (TEPC) is what is used to measure radiation doses on tissue equivalent, or carbon based, cell models. While our team has worked to develop our own TEPC for use in our planned payload, there is also a TEPC existing aboard the ISS.

The IV-TEPC (Intra-Vehicular TEPC) is within the confines of the ISS and acts as a dosimeter/exposure tracker for the astronauts on board. This placement means it only receives the radiation that makes it through the intense ISS shielding. Another main purpose is to validate the efficacy of the shielding.

The difference between our team’s TEPC and the existing IV-TEPC aboard the ISS is the differentiation of charged and neutral particles. While our TEPC can perform this differentiation, it also does so outside the shielding of the ISS. The result is a more accurate prediction of the ambient radiation dose.

In the picture above, the circled gold cylinder is the ISS’s IV-TEPC.

In the picture above, the circled gold cylinder is the ISS’s IV-TEPC.

The NEUDOSE mission’s TEPC design - capable of ionizing vs non-ionizing radiation differentiation.

The NEUDOSE mission’s TEPC design - capable of ionizing vs non-ionizing radiation differentiation.

Apollo 11 Anniversary - Radiation

On this day 50 years ago, a landmark of human achievement occurred when Neil Armstrong and Edwin “Buzz” Aldrin set foot on the lunar surface. However a danger present to all, including Michael Collins in lunar orbit, was the very real threat of radiation exposure. En route to the moon, the crew needed to go through the upper and lower Van Allens belts, doughnut shaped belts around the Earth filled with captured radiation trapped within the Earth’s magnetic field. Even after passing the Van Allen Belts, the crew was vulnerable to unpredictable solar flares.

Each crew member carried a Personal Radiation Dosimeter that detected the amount of radiation they were exposed to. Surprisingly, the Apollo 11 crew received one of the least amounts of radiation in the Apollo missions. The crew got very lucky that no major event occurred during and they were routed safely around the more dangerous parts of the Van Allen belts.

A major concern for future manned space missions is radiation exposure, especially when considering a mission to Mars. The NEUDOSE mission aims to shine more light on the nature of ionizing radiation on the human body. Our team hopes that one day we will look back on the first manned mission to Mars in the same way we reflect on the success of Apollo 11 today.

Edwin “Buzz” Aldrin on the lunar surface on Apollo 11

Edwin “Buzz” Aldrin on the lunar surface on Apollo 11

Personal Radiation Dosimeter (PRD) worn by Apollo astronauts

Personal Radiation Dosimeter (PRD) worn by Apollo astronauts

Canadian Inventions

It’s Canada Day weekend and we like to reflect on the influence Canadians have had in Space. There have been many Canadian heroes that have spent time in space, in the ground station, and in the design room. The NEUDOSE mission team aims to join the roster of great influential Canadian inventions.

The Canadarm: The first Canadian space invention most citizens think of - the robotic arm has had significant influence on operations on the ISS. With 2 generations, the Canadarm is still operational to this day.

Space Greenhouse: University of Guelph’s Mike Dixon and his team have developed 14 hypobaric chambers to study the effects of atmospheric pressure on plant growth.

Apollo landing gear: The legs of the lunar modules that brought the first men to the moon were developed by Quebec’s Heroux-DEVTEK . The light-weight aluminum legs made sure the landing was sufficient to allow Neil Armstrong and Buzz Aldrin to leave the module.

The Spherical TEPC

The CNP-TEPC is the main differentiator in the NEUDOSE mission from other CubeSat projects. The instrument reacts differently in ionizing vs non-ionizing radiation. It does this with a combination of the 2 cooperating technologies. The Spherical TEPC (pictured below), which is filled with enriched propane gas to model a human cell , is fabricated using the most recent techniques developed by NASA. It has a wall made of electrically conductive tissue-equivalent plastic.

When this instrument reacts with radiation, an electrical current is triggered through the anode wire sticking out of the poles. If at the same time a reaction occurs in the surrounding Anti-Coincidence Detector (ACD), we will know that we have received charged radiation. If we do not, then it is simply just neutral or non-ionizing radiation. The CNP-TEPC is the primary science payload and is currently being designed to be small enough so it can also potentially fit on the Extravehicular backpack carried by astronauts during spacewalks.


Opportunity has passed

On February 13, NASA had declared the Opportunity rover had officially ceased communication. Opportunity was deployed in 2003 and was anticipated to operate for 90 days, but has remained functional for a record 15 years. Opportunity’s mission was to analyze Martian soil for traces of water, of which it has confirmed is present. The mission results validate and encourage our desire to explore the red planet.

Our NEUDOSE mission seeks to ensure that humanity will be able to perform safer space travel, with a more advanced knowledge of the effects of solar radiation on humans outside our Earth’s protective magnetosphere. Our CNP-TEPC (Charged and Neutral Particle - Tissue Equivalent Proportional Counter) instrument allows us to distinguish between ionized and non-ionized radiation and to estimate doses received during space travel.



CNP-TEPC Instrument reacting to radiation

CNP-TEPC Instrument reacting to radiation

Total Eclipse of the Moon

Tonight, the Total Lunar Eclipse will be visible in Hamilton. A lunar eclipse, when the Earth casts a shadow on the moon, is quite a rare event and Totality will not be visible in Hamilton again until May 2022. The moon turns a red colour once the Earth fully blocks the sun. Similar to the ring we see during an annular solar eclipse, the moon sees a bright red ring around the Earth. This ring is red due to the contents of our atmosphere. Volcanic activity is also capable of influencing the appearance of the moon during an eclipse and can make it significantly darker.

For more information and a live animation of tonight’s total lunar eclipse, visit this link.

Progress in practice


As the year begins to draw to an end, we reflect on our progress and challenges overcome throughout the year. One example of progress in our NEUDOSE mission is in our Pressure Vessel Enclosure, designed by our Mechanical team. The picture above shows the design iterations (in order from left to right). As the project progressed, certain parameters continued to change/develop. Some of these design constraints include: Space requirements, strength of the material, load capabilities, and ease of integration. Our experienced team adapted to these changes and proceeded to apply their skills and knowledge, refined at school here at McMaster University, to the design changes.

Fun Fact: Theoretically, a sphere is the optimal shape of a pressure vessel due to the even stress distribution. However, due to the difficulty and cost of manufacturing a perfect sphere, often cylinders with rounded ends are used.

Soldering Lecture Oct. 1 @ CNH 103

Soldering is the fundamental process that allows for the creation of structural and electrical bonds between two separate objects. It is necessary for the fabrication of most microelectronics; from computers to cellphones, and even to satellites! But what happens when we send these soldered electronics to the vacuum of space?

Find out at our second General Lecture! Monday October 1st, at McMaster University’s Chester New Hall (CNH) 103 @ 6:30 pm.