The Hubble Space Telescope was primarily designed to study the formation and evolution of galaxies, as well as the properties of stars and planets.

The Hubble Space Telescope was launched on April 24, 1990, aboard the Space Shuttle Discovery.

The Hubble Space Telescope is approximately 13.2 meters (43 feet) long and 4.2 meters (14 feet) in diameter.

The Hubble Space Telescope weighs approximately 11,110 kilograms (24,500 pounds).

The Hubble Space Telescope orbits Earth in a low Earth orbit (LEO), at an altitude of approximately 547 kilometers (340 miles).

The Hubble Space Telescope's mission was originally expected to last for 5 years, but it has been extended several times and is now expected to last for 20 years.

The Hubble Space Telescope's primary instrument is the Wide Field and Planetary Camera 2 (WFPC2), which was installed during the first servicing mission in 1993.

Dark matter is a type of matter that does not emit or reflect light, making it difficult to detect directly.

Evidence for the existence of dark matter comes from observations of the rotation curves of galaxies, the gravitational lensing of light, and the cosmic microwave background radiation.

The estimated amount of dark matter in the universe is approximately 85%, with ordinary matter making up only about 15%.

There are several theories about the nature of dark matter, including weakly interacting massive particles (WIMPs), axions, and sterile neutrinos.

There are several challenges in studying dark matter, including the fact that it is difficult to detect directly, it does not interact with ordinary matter very much, and it is spread out over large distances.

Dark matter may play a role in the formation and evolution of galaxies, affect the expansion of the universe, and be a source of energy.

Ongoing research efforts to study dark matter include direct detection experiments, indirect detection experiments, and theoretical studies.

Future directions for research on dark matter include developing more sensitive direct detection experiments, searching for new indirect signatures of dark matter, and exploring new theoretical models of dark matter.