AstronomyPhysics

What is the ISS?

On the 15th of December 2015, British Astronaut Tim Peake boarded the International Space Station for ISS Expedition 46 and 47. His mission has been named ‘Principia’, a reference to Isaac Newton’s ‘Philosophiæ Naturalis Principia Mathematica’ in which Newton writes about the laws of motion, universal gravitation and various other laws of physics. A direct quote from the official Principia Mission website explains that the mission “will use the unique environment of space to run experiments as well as try out new technologies for future human exploration missions.”. The website also explains how Tim’s mission will allow him and his to crew to “work on experiments that cannot be done anywhere on Earth.” So what can be done on the ISS which can’t be done on Earth and why?

What is the ISS?

The International Space Station is a spacecraft inhabited by groups of astronauts and cosmonauts as they use the ISS as an active science laboratory. It’s operators are a diverse collaboration between different space agencies of diverse locations: NASA (North America), JAXA (Japan), The Canadian Space Agency, The European Space Agency and Roscosmos State Corporation (Russia). The first component of the ISS was a collaboration between the US and Russia. It was known as the ‘Functional Cargo Block (FGB)’ but nicknamed ‘Zarya’. The US designed and funded ‘Zarya’ and the Russians built and launched it on November 20th 1998 on a Russian ‘Proton’ rocket. At the time of writing this, it remains the largest man-made object in Earth’s orbit. As of 15th of December 2015, there has been 376 flights to the ISS and 221 people on the ISS in total from 18 different countries and 10 different space agencies. There have also been 7 tourists on the ISS from the Virginia based space tourism agency Space Adventures, Ltd. There have been 46 expeditions on the ISS with 100 different crew members. The current expedition: Expedition 46 consists of the following crew: Commander Scott Kelly, Sergy Volkov, Mikhail Kornienko, Timothy Kopra, Tim Peake and Yuri Malenchenko.

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What does the crew do on the ISS?

 One of the main purposes of the ISS is to research and perform experiments which cannot be carried out on Earth. These experiments fall under various categories: Biology and Biotechnology, Earth an Space Science, Educational Activities, Human Research, Physical Sciences and Technology. According the official NASA FAQ ‘Astronauts Answer Student Questions’ PDF file on the NASA website, it is also the duty of the crew to make sure that the station is in top shape which includes having to clean the ISS and its equipment, maintain equipment and repair and replace it if necessary. Crew members also have to exercise around 2.5 hours a day to keep their bones and muscles strong. If they don’t, they begin to lose bone and muscle and they become weak, severely limiting their ability to work aboard the ISS. The crew uses treadmills, resistance bands and other equipment to exercise efficiently onboard the ISS. Maintaining the ISS often means the astronauts must work outside the station. It is known as Extravehicular activity (EVA) and examples include repairs, maintenance, experimentation, satellite deployment and repair etc. To leave the space station astronauts equip a pressure space suit and begin depressurisation in an airlock. The same procedure is carried out to re-enter the space station.

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How does the ISS communicate with Earth?

 The ISS crew also spend time communicating with Earth. This is done through a satellite system called the Tracking and Data Relay Satellite (TDRS). The system was set up in the early 70’s and is the same relay system the Hubble Space Telescope uses to send images captured back to earth. There are 3 generations of TDRS satellites. Each TDRS satellite has a letter for identification, the newest being TDRS-M which is available for launch this year. The last TDRS satellite used was the TDRS-L on January 23rd 2014. When one of the satellites reaches their orbit, the identification name turns from a letter to a number (e.g. TDRS-A became TDRS-1). Older first generation satellites communicated on the microwave IEEE S-band which ranges from 2 to 4Ghz. However newer second and third generations communicate using microwave IEEE S-band, IEEE Ku-band which ranges from 12-18Ghz and IEEE Ka-band which ranges from 26.5 to 40Ghz.

The satellites then send all signals down to a ground terminal (receiving antenna) which is relayed to Mission Control Center. The two primary ground terminals are both located in the White Sands Complex in New Mexico, the first being ‘White Sands Ground Terminal’ and the second being the ‘Second TDRSS Ground Terminal’. Video, Audio and Experiment data is all sent to the ground terminals.

Experiments on the ISS

One of the main purposes of the ISS is to be a laboratory for all kinds of scientific and technological research and experimentation. Robonaut is one of the greatest examples of technology being developed on the ISS. Robonaut is a humanoid robot created to work aboard the ISS. According to NASA’s experiment webpage, Robonaut can “manipulate hardware, work in high risk environments, and respond safely to unexpected obstacles.”. Robonaut is designed like a human, so it will be able to work human jobs. Robonaut is currently able to use switches, install handrails and perform other maintenance jobs on the ISS. Robonaut 1 was an upper body humanoid which could optionally be attached to a rover, however Robonaut 2 has recently has had climbing legs developed which could aid with certain work on the ISS. A system known as “The Robonaut Teleoperations System” will allow the crew members to remotely control Robonaut through motion control. Motion control gloves, vest and mask will allow a crew member to see through Robonaut’s perspective and control various parts of the body. This would allow the crew members to operate hazardous work aboard the ISS, and with further developments, may soon be able to operate EVA work safely without putting anyone in danger. A biological experiment known as the Vegetable Production System or Veggie. It is a unit which can produce “salad-type crops” so the crew is able to grow and eat vegetables in space. It will provide the crew with a safe and continuous source of food. It will also be a ground for new experiments on how plants react with gravity and what the difference is between the plants grown in space and on earth. It will also give us a better understanding of plant growth and give us new ways to improve plant growth on earth. Seeds are placed on small pillows in the chamber. The pillows are put into a root mat into one of the bellows built into Veggie. The pillow is layered with a specific fertiliser and clay to improve aeration. It uses the environment of the cabin as a source of carbon dioxide and thermal control as well as using LEDs to provide lighting to the plants. Water is routinely injected into the root mats to start the seed germination. Veggie will allow astronauts to have a source of fresh food to improve astronaut wellbeing and nutrients intake. It would also mean the ISS would not have to get re-stocked/re-supplied as often, which would save fuel and other valuable resources. Also, growing food would allow for longer expeditions, and more importantly, further expeditions, which could allow astronauts to go to distant planets without needing re-supplies. Which could end up being a critical part of NASA’s long distance journey to Mars.

 

The ISS and it’s unique environment has allowed for some amazing scientific and technological experimentation and future innovation to say the very least. It’s exciting to see what experiments Principia will bring.

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