Researchers Make More Accurate Observation of Earth System Possible

Sep 22, 2004

Researchers at the Faculty of Aerospace Engineering of TU Delft have succeeded in modelling the rotational behaviour of two satellites with unprecedented accuracy. This makes it possible to model the orbit of the satellites much more accurately and this means that changes on earth observed by the satellite are also more accurate, for example, melting of the polar icecaps or the transport of water and atmospheric mass around the globe.

Satellites often have a rotational movement after being launched. This rotation and the mechanical characteristics of the satellites influence their orbits. This phenomenon was previously described using a number of (incidental) measurements and a rough model. The model created by the Delft PhD Student Nacho Andrés and his supervisor Ron Noomen, together with colleagues from the United States, Italy and Japan, removes much uncertainty about the behaviour of satellites.

The rotational movement of satellites varies in time, from rapid movement, to almost none at all. Both situations have very different consequences for the temperature distribution on the satellite’s surface, and therefore on the size and direction of the so-called thermal forces that result from non-uniform heat radiation. These thermal forces are incredibly small, a factor 1013 smaller than the gravity that governs our everyday lives. Still, being able to calculate these small forces is important in the calculation of a satellite’s orbit.

The model that the researchers of the department of Earth Observation and Space Systems together with their international colleagues have developed, represents the orbital behaviour of the LAGEOS-1 and LAGEOS-2 satellites (launched in 1976 and 1992 respectively) with extreme accuracy (up to 1 cm). The model, called LOSSAM (LAGEOS Spin Axis Model), is based on independent observations of the rotation of satellites. It computes a whole range of forces that act on the satellites. LOSSAM provides an accuracy improvement of up to 50% over previous models. The new model is especially relevant for the rotational behaviour of LAGEOS-1 since 1998, because here, other models fail to produce results.

The research results have been published in a recent edition of the scientific Journal of Geophysical Research. In a follow-up project, the thermal and conductive characteristics of the satellites will be included, allowing a comprehensive thermal model to be constructed. This will, of course, further increase the accuracy of the model and therefore the satellites’ readings.

Source: TU Delft

Explore further: Fermi finds a 'transformer' pulsar

add to favorites email to friend print save as pdf

Related Stories

The camouflage games: Can you spot the bird?

Feb 20, 2014

So how long did it take you to spot the nightjar in the video on this page? For the predators trying to outsmart their concealed prey it's about not going hungry. But for the birds and the eggs that they ...

Cuckoos stay on course

Jan 14, 2014

With short hectic wing strokes that are hardly raised above the body, the flight of the cuckoo is not the height of elegance. Nevertheless, their wings carry them over 16,000 kilometres a year. Martin Wikelski ...

Recommended for you

Fermi finds a 'transformer' pulsar

13 hours ago

(Phys.org) —In late June 2013, an exceptional binary containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed. The pulsar's radio beacon vanished, while at ...

New launch date set for ISS delivery vessel

14 hours ago

A robot ship will be launched from Kourou, French Guiana, after a five-day delay on July 29 to deliver provisions to the International Space Station, space transport firm Arianespace said Tuesday.

The heart of an astronaut, five years on

15 hours ago

The heart of an astronaut is a much-studied thing. Scientists have analyzed its blood flow, rhythms, atrophy and, through journal studies, even matters of the heart. But for the first time, researchers are ...

User comments : 0