July 2, 2013
Science Experiment Requires New Altitude For Space Station
Lee Rannals for redOrbit.com - Your Universe Online
Crew members aboard the International Space Station (ISS) had to add a little more distance between the orbiting laboratory and Earth on Sunday for a science experiment.
"The European scientists requested that we reposition the station slightly because by having this period of time they could bridge over the two Solar observing visibility windows, allowing them to view the sun for a full solar rotation without interruption," said International Space Station Program Scientist Julie Robinson, PhD. "The International Space Station Program took a look at the request and was able to change the station's position to increase science return."
This adjustment offers an additional opportunity to follow an entire solar rotation, about 27 days as determined by viewing sunspots from Earth.
"A very important contribution from the Solar 'bridging' measurements is the possibility it brings to perform inter-comparisons over an entire period of a Solar rotation with data from other solar instruments in orbit (e.g. a comparison of ESA's Solar-SOLACES data and NASA's SDO/EVE data)," said ESA Solar Project Scientist Astrid Orr, PhD. "The December bridging already shows that these particular data sets agree extremely well with each other."
NASA said measurements for this Solar window run from June 18 to July 23. Normally viewing from the station only allows for short visibility windows of 10 to 12 days at a frequency of about once a month. After this, the observation window is blocked by the structure of the station. Changing the position of the station increases the visibility of the sun and enables scientists to view a full rotation from the orbital vantage point.
"The bridging makes it possible for the scientists to develop a method for 'melting' both sets of data into one reference set of data in absolute physical values for the science community, which includes both solar physicists and climate researchers," said Orr.
The station's orbit is turned so it is mostly sunlit, giving instruments optimal opportunity for measurements. This meets the solar science team's requirements to observe the sun through a full solar rotation. After observations are complete the station will return to its standard altitude, but investigators will continue to collect data.
"The Solar detectors perform very accurate measurements of the sun's flux: they are measurements in absolute values. In other words, the real amount of flux emitted by the sun in physical units," said Orr.
"This may sound trivial but it is in fact quite difficult to achieve. Many detectors looking at the sun provide only measurements in relative units. On the other hand, absolute measurements are important in order to understand the amount of energy that the sun is emitting and that we receive at the Earth. Like, if somebody has a fever and you are trying to measure their temperature: you can put your hand on their forehead and say that it's hot, or else you can actually measure the temperature with a thermometer. It is useful if the thermometer that you are using has its units stated correctly, otherwise your measurement will be of little use."