HUBBLE TELESCOPE

1. Context

2. About Hubble Space Telescope

• The Hubble Space Telescope is a large telescope in space.NASA launched Hubble in 1990.
• It was built by the United States space agency NASA, with contributions from the European Space Agency.
• Hubble is the only telescope designed to be serviced in space by astronauts.
• Expanding the frontiers of the visible Universe, the Hubble Space Telescope looks deep into space with cameras that can see across the entire optical spectrum from infrared to ultraviolet.
• The Hubble Space Telescope makes one orbit around Earth every 95 minutes.

3. Achievements

• It has helped in discovering the moons around pluto. Evidence regarding the existence of black holes has emerged based on observations through Hubble.
• The birth of stars through turbulent clouds of gas and dust has also been observed.
• The Hubble telescope made observations of six galaxies merging together.
• On February 11, 2021, Hubble made observations of small concentrations of black holes.

4. Images recorded by the Hubble are spoiled by passing satellites

• A study, published in the journal Nature Astronomy, reveals an increase in the percentage of images recorded by the Hubble that is spoiled by passing satellites.
• Thousands more satellites have been launched since then by SpaceX and other companies, and many more are expected to go into orbit in the years ahead, affecting the Hubble and potentially other telescopes in space.

Image Source: The Indian Express

5. Legacy of Hubble Space Telescope

• The Hubble Space Telescope’s legacy cannot be overstated.
• Because of the observatory, we now know, for example, that the universe is 13.8 billion years old, that most galaxies contain a supermassive black hole at their centers, and that stars form in violent processes.
• The Hubble images including the gorgeous clouds of gas and dust in the "Pillars of creation" and the view of nearly 10,000 galaxies in the "Hubble ultra deep Field" never fail to inspire.
• But the number of satellites in orbit has significantly increased since the Hubble launched in 1990, and now it is staring at the cosmos through a field of satellites.

6. Findings of the study

• To quantify the effect of satellite constellations on Hubble, Sandor Kruk, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany, and his colleagues analyzed an archive of images taken from 2002 through 2021.
• They had help from hundreds of citizen scientists who pored through images to tag those with clear satellite streaks.
• That data set was then used as a training set for a machine-learning algorithm that analyzed more than 100,000 individual Hubble photos.
• Their results show that the chance of seeing a satellite in a Hubble image from 2009 to 2020 is only 3.7 percent.
• But the chance of seeing one in 2021 is 5.9 percent an increase that they say corresponds to Starlink. By the date of the analysis, 1,562 Starlink satellites were in orbit. Another company, OneWeb, had lofted 320 satellites. 

7. Threats posed by SpaceX Satellites

• The satellites could pose a serious threat to a telescope that hasn’t launched yet.
• At the end of this year, China plans to send Xuntian, also known as the Chinese Survey Space Telescope, into low-Earth orbit.
• Xuntian will have a larger field of view than Hubble, making it much harder for satellites to slip by undetected.
• And Xuntian can’t simply launch into a higher orbit. China’s plan is for the telescope to share an orbit with the Tiangong space station so that astronauts can refurbish it if necessary. 
• There are simply too many unknowns at the moment, including the ultimate number of satellites.
  SpaceX hopes to eventually expand the size of its fleet to 42,000 Starlink satellites.
• Many other companies are in the market, too: Amazon, the British satellite provider OneWeb, a Chinese company called Galaxy Space, and even governments.
• A combined 431,713 satellites are planned to launch in the coming years.

For Prelims