ПадалкаGood day! My name is Gennadi Padalka and today I want to tell you about a Russian experiment with a satellite. The objective of this experiment is to obtain more exact knowledge of atmospheric parameters, in particular, atmospheric density in orbits 100-400 km above ground. Therefore, let me present to you one more satellite to be put into outer space on August 20, 2012. And when I say “one more satellite” I want to emphasize the fact that Russian cosmonauts have accumulated a great deal of experience in launching satellites from the ISS orbit, they did it several times before. The most recent example was when just a little more than a year ago during his spacewalk Sergei Volkov launched satellite RadioSkaf-2, and now it’s our turn. We’ll eject the satellite in the direction opposite to the ISS velocity vector, thus assuring safe orbital motion of the two vehicles: the satellite and the ISS.

And now let me say a few words about the process of launching satellites from the ISS orbit: When, during a spacewalk, I’m holding it in my hands, the satellite and the ISS orbit the Earth with the same velocity of about 8 km per second. My task during the spacewalk is to eject the satellite from the launching device, which is a frame structure consisting of 6 arcs ending in spring-loaded holders. At the points where the sphere touches the holders there are teflon pads preventing damage to the sphere.

As a result the satellite will gain the velocity of ~ 0.5 m per second with respect to ISS against the station velocity vector. Since the satellite will have a lower velocity than ISS, it will go into a lower orbit. Moving along an orbit with a smaller radius, after some time the satellite will find itself ahead of and below ISS.

Before I push the satellite out of its launching device, I will have to remove two types of restraints which currently prevent the satellite from separating.

When talking about launching satellites by the crew during a spacewalk, it is important to note that it is not the only task of the spacewalk, that launching a satellite is just one of its tasks. Performing 3-4 spacewalks per year, we could launch one more satellite during each spacewalk. This is important and serious potential of the ISS Russian Segment. So, RSC Energia awaits proposals on preparing and launching from ISS new Russian satellites for various purposes.

Let’s now talk about scientific objectives of the satellite. This satellite has the shape of a perfect sphere. The dimensions and mass of the satellite are known precisely – it is 530 mm in diameter and has the mass of 7.96 kg.

20-08-12

Since the satellite mass and dimensions are known, the satellite orbital motion (which will be tracked by Russian ground stations) is used for calculating the atmospheric density and updating the parameters of the atmospheric model. The satellite deceleration rate is proportional to the atmospheric density, which, in its turn, depends on the orbital altitude and the level of solar activity: the more intense the solar activity, the higher the atmospheric density at a specific altitude and vice versa. Before burning up during reentry into the dense atmosphere, the satellite will be slowly, over a period of no less than several months, descending from the altitude of 400 km to 80 km, where the Earth atmosphere will be so dense that the satellite will heat up and burn. Observations of the satellite motion at different altitudes will be used for updating the model of the Earth atmosphere.

Our test satellite can also be used for determining the exact mass of the station. There are GPS and GLONASS receivers installed onboard the ISS. Data from these receivers enable exact determination of the station trajectory after the satellite separation. The exact knowledge of the satellite mass and trajectory makes it possible to deduce the air density at the ISS orbit, and the space station mass can be determined using the ISS trajectory measurements taken by GPS and GLONASS receivers. This satellite can also address other scientific problems. But we’ll tell you about this in other reports. Thank you for you attention! And now we are going to show you the satellite separation in space during the space walk.

Геннадий Падалка - о запуске с...
Геннадий Падалка - о запуске спутника 20 августа 2012г.

 

 

 

 

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