many thanks to frank w.cianciolo who has explained to me the scientific research program they are doing at the observatory . read the article he has given to me, it´s really worth it! the researchers hope they soon will understand more about the dark matter and the dark energy . exciting!!!
and here the link to mc donald observatory , they provide much more information.
HETDEX: Leading the Revolution
HETDEX will be the first major experiment to search for dark energy. It will use the giant Hobby-Eberly Telescope at McDonald Observatory and a set of spectrographs to map the three-dimensional positions of one million galaxies
Hobby-Eberly Telescope [Martin Harris/McDonald Observatory]
A scientific revolution is underway. It will tell us more about the universe than we have ever known before, because it will tell us what makes up almost three-quarters of all the matter and energy in the universe. It will tell us if the laws of gravity are correct, and reveal new details about the Big Bang in which the universe was born.
The subject of this revolution is dark energy, a mysterious force that is causing the universe to expand faster as it ages. And one of the leaders in the revolution is HETDEX — the Hobby-Eberly Telescope Dark Energy Experiment — at The University of Texas at Austin McDonald Observatory. Its observations will narrow the list of possible explanations for dark energy, and may even provide the final answer.
HETDEX will combine the immense light-gathering power of the Hobby-Eberly Telescope, the world’s third largest, with an array of new instruments for analyzing the light from distant galaxies.