Collaborative efforts by many nations make the International Space Station and its remote sensing technologies possible and beneficial to humanity.
How do astronauts wash their hair in space? How do they go to the bathroom? How do ants behave in microgravity? Talking about the International Space Station (ISS) opens a floodgate of questions for anyone with even a passing curiosity.
The ISS, roughly the size of a football field, took 10 years to construct. The first portion of the station launched in 1998 aboard a Russian rocket, Zarya. Since then, 214 people have traveled there, and according to NASA, it now has more livable accommodations than a six-bedroom house.
According to Julie Robinson, ISS chief scientist, the station is the result of unprecedented peaceful cooperation with 82 countries, to date, working on technology development, launches, data collection, training, and more. There is an emerging effort, spearheaded by Space Safety Magazine, to award ISS the Nobel Peace Prize.
The pieces of the station were built in countries with different languages, cultures, legal frameworks and measurement systems. ISS was assembled during 160 spacewalks with parts delivered by more than 100 space flights.
ÛÏA module built in Russia was financed by the U.S. and launched from Kazakhstan,Û Space Safety Magazine notes. ÛÏA cargo carrier was built mostly in Italy, launched from French Guiana, monitored by a control center in France, and designed to dock with a module built in Russia. Another cargo carrier was built in Japan and designed to attach to a module built in the U.S. using robotic elements built in Canada.Û
In 2005, Congress established the U.S. portion of ISS as a national laboratory. The full effects of this declaration did not take effect until the construction was completed in 2011. That same year, NASA selected the nonprofit Center for the Advancement of Science in Space (CASIS) to manage the lab.
Robinson explains, ÛÏIt opens ISS up for other agencies. That declaration says whoever needs to use the lab can have access, and it also opens it up to commercial partnerships.Û
Educational institutions and agencies, like the National Institute of Health (NIH) and the National Oceanic and Atmospheric Administration (NOAA), now have access to this unique environment for research. CASIS helps provide funding, expertise, support, launch access and educational outreach to those interested in utilizing the lab.
With construction complete, the station is poised to become a unique platform for Earth observation.
Matt McGill is the principal investigator and project manager for NASA’s Cloud-Aerosol Transport System (CATS), which will be installed on the Japanese module of the station in December.
He explains, ÛÏFrom an Earth science-centric perspective, it’s a low-cost opportunity because the platform already exists. You have the ability to build an instrument for cheap, and you’re piggy-backing the instruments on rockets that are already paid for and going there.Û CATS cost $13 million. Generally, Earth science missions start at around $500 million.
Of course, as with almost anything, there are pros and cons with using the ISS for Earth observation.
Launch vehicles to and from the station create exhaust that can affect delicate sensors. On the other hand, as McGill notes, frequent resupply missions offer opportunities for transporting instruments and parts if something stops functioning properly.
Additionally, instruments need to be turned off during space walks and docking missions for safety. If the research requires a continuous data stream, this can be problematic.
In the pro column, the station provides an almost unlimited power source, and removes constraints on the size and mass of payloads. ÛÏIssues that you spend a lot of time fussing with like mass are greatly reduced,Û said McGill. ÛÏThis thing is a battleship; for some of these payloads, you’re allotted 500 to 1,000 kilograms. So, you don’t have to spend a lot of money light-weighting and using exotic, expensive materials.Û
Because the station is already operational, the infrastructure is in place for collecting and transmitting data. There are control centers set up in the United States, Canada, France, Japan, Germany, and Russia ÛÒ manned 24 hours a day, year-round.
Additionally, the station’s orbital path, which moves between 51.6 degrees north and south, impacts the types of observations possible.
Cloud-Aerosol Transport System (CATS)
For CATS, the station’s orbit is ideal because it follows the primary aerosol transport paths, and allows for observations about changes in clouds and aerosols (dust, smoke, pollutants, or volcanic ash) from day to night. These particles reflect or absorb sunlight, and play a part in how clouds are formed. Understanding these interactions will allow for more accurate modeling of the Earth’s climate and temperature-regulating systems, McGill says.
He adds, ÛÏWe’re interested in how clouds and aerosols interact. For example, you hear about hurricanes. Are hurricanes intensified by Saharan dust, or are they suppressed by the presence of Saharan dust? The more we can capture in a day to night fashion and observe what’s going on the better. It’s a very different data set than what we get from other satellites.Û
CATS is a multipurpose mission that will provide important information about these processes, and test new technologies for future free-flying satellites.
CATS is composed of two lasers with three wavelengths, a beryllium telescope and extremely sensitive receivers; together these instruments are able to precisely measure the type, quantity, and altitude of aerosols. The device is the size of a standard refrigerator and weighs 500 kilograms. The data stream provided by CATS will be fed into a variety of models that can be used to predict how these particles travel and their impact on climate.
At the moment, similar data is coming in from NASA’s CALIPSO spacecraft, which launched in 2006 and flies in formation with the A-Train constellation. Since its launch, CALIPSO has greatly enhanced the understanding of how clouds function in the planet’s climate feedback system. The satellite was designed for a three-year mission; CALIPSO is still operating, but it’s using its second laser. When that laser goes caput, the satellite will cease collecting data.
The next proposed NASA mission that could continue gathering this type of data, Aerosol-Cloud-Ecosystems (ACE), is still at least 10 years out.
ISS-RapidScat will head to the station in September. It was designed to replace a satellite, QuickScat, which collected data on ocean winds for a decade and ceased functioning properly in 2009. The devise was constructed in 18 months with spare parts from QuickScat at a cost of $26 million.
Currently, the Indian Space Research Organisation (ISRO) and the European Space Agency (ESA) both have satellites with instruments similar to what ISS-RapidScat uses. According to Ernesto Rodriguez, RapidScat principal investigatoråÊthe station’s orbit, which circles the Earth every 90 minutes, will allow scientists to fine tune measurements in ways that have never been possible before; ISS-RapidScat will be used to cross calibrate the data with these international satellites.
ÛÏSun-synchronous satellites don’t see each other very frequently, so cross calibration will really strengthen the data,Û said Rodriguez. When satellites pass over the same point, the data is compared and adjustments can be made for greater accuracy.Û
ISS-RapidScat and the other spacecraft use scatterometers, which are microwave radars that measure ocean winds by sending high radio frequency signals down. The signals bounce back, or scatter, and the returning signals can be measured to determine wind speed and direction. Smooth water returns weaker signals, and rough water returns stronger signals. The station will pass over the same locations at different times; this will allow researchers to see how short-term changes over the course of a day potentially influence long-term changes over the course of weeks or months.
Mark Bourassa is a meteorology professor at Florida State University. He specializes in remote sensing technologies that observe the interaction between sea and air. ÛÏWhen we say ocean winds, we mean winds about 10 meters above the ocean surface. These winds are important because they represent the friction at the bottom of the atmosphere, which is important for high and low pressure systems; the mixing at the top controls ocean circulation and currents.Û
Coupling an understanding of the ocean and atmosphere together is crucial for climate studies and forecasting.
Paul Chang, NOAA’s ocean surface winds science team leader, has worked closely with Rodriguez and his team. When QuickScat was functioning properly, Chang helped transition the data stream over to the National Weather Service for forecasting purposes; he will do the same with information from ISS-RapidScat. He stresses that having the best data in hand is crucial to supporting the decision-making process.
While scientists are looking forward to working with the data that ISS-RapidScat will provide, the instrument only has two years on the station; after that another mission is scheduled to take its spot on ISS. European and Indian satellites will continue to collect information about ocean winds, but these instruments do not have the coverage that QuickScat once did, according to Chang and Bourassa.
Chang notes, ÛÏIn the short term, we are going to have to depend on our international partners and leverage what they are doing. After ISS-RapidScat, there’s nothing planned to measure ocean vector winds. It’s not going to stop the weather service from forecasting, but there are fewer measurements available to help them do that more accurately.Û
In the future, Chang would like to see two satellites with scatterometers routinely measuring large swaths of the ocean; two satellites could provide data every six hours. Relying on the current satellite orbits ÛÏis sort of a hit or miss thing, the satellites have specified areas that they pass over every day,Û said Chang. As they orbit over moving weather patterns, they may or may not capture the data if they aren’t passing over where the weather is actually happening.
Exploration and Discovery
Going to space is certainly a costly enterprise — international partners spent roughly $100 billion to build ISS. Efforts to truly measure the economic impacts of space exploration and research are difficult to quantify. There are tangible products like LASIK eye surgery or the next generation of miniaturized computer components, and the potential to save countless lives and billions of dollars if we can accurately predict when and where the next big storm will make landfall.
Scores of astronauts in the station partnered with scientists on Earth also have been able to work on diverse projects like vaccine development, testing cancer-fighting drugs and designing solar powered water filtration systems. A robotic arm, developed for ISS by MacDonald Dettwiler in Canada was adapted to perform complex brain surgeries inside an MRI machine. This technology allows surgeons to execute delicate operations with a level of accuracy that couldn’t be achieved with human hands alone.
Robinson is amazed by what’s been accomplished so far, and perplexed by how little people seem to understand about the ways that work taking place at the ISS impacts our daily life on Earth.
The bottom line is that aerospace innovations have countless real world applications that, perhaps, aren’t easily viewed through a cost-benefit lens.