NASA launched its new flagship space telescope, the Nancy Grace Roman Space Telescope, into space from Florida on Sunday. The roughly $4 billion observatory will study some of the biggest questions in astrophysics and cosmology. It will focus on dark energy, dark matter, gravity and planets beyond our solar system.

A SpaceX Falcon Heavy rocket carried the telescope into space from NASA’s Kennedy Space Centre. Weather conditions raised some concerns before the launch, but the rocket lifted off under blue skies with some scattered clouds.

Roman will now travel toward Lagrange Point 2, an orbital location about a million miles, or 1.6 million kilometres, from Earth. NASA has planned the telescope’s main mission for five years. The space agency said Roman could have enough fuel to continue its work for another five years.

The telescope will expand on the work of major space observatories such as the James Webb Space Telescope and the Hubble Space Telescope. Webb launched in 2021, while Hubble began its mission in 1990. Roman will take a different approach by covering much larger areas of the sky at a faster rate.

"It will be as if Hubble and James Webb kind of peered through a keyhole at the universe, while Nancy Grace Roman will kick the door down," Nicola Fox, chief of NASA's Science Mission Directorate, told reporters on Saturday.

Roman will have a level of sensitivity and image sharpness similar to Hubble. Its major advantage will be the speed at which it can survey the sky. Julie McEnery, Roman's senior project scientist at NASA's Goddard Space Flight Centre in Maryland, explained the difference during a briefing in July.

"Roman has broadly the same sensitivity and sharpness of vision as Hubble, but we survey the sky much faster," Julie McEnery, Roman's senior project scientist at NASA's Goddard Space Flight Centre in Maryland, told reporters at a briefing in July.

McEnery said Roman will be able to survey the entire Milky Way in just one month. Hubble would need around a century to carry out the same survey.

"One month of observations to survey our Milky Way galaxy would take about a century with Hubble," McEnery said.

The telescope will complement the James Webb Space Telescope, which has already changed scientists’ understanding of the early universe. Webb has found that some of the earliest galaxies formed earlier and grew larger than scientists had previously expected. It can observe distant objects and look back into the universe’s early history through the light that has travelled across space for billions of years.

Roman will instead provide broad, panoramic views of the universe. NASA compares Roman to a camera’s wide-angle lens, while Webb works more like a zoom lens. Webb can study rare and distant objects in great detail, while Roman can observe much larger sections of the sky.

"Webb is designed to be able to probe very deeply and with exquisite sensitivity into the universe, so we can find rare things in the early universe," McEnery said, while Roman offers "the large vision that complements the deep views that Webb provides."

One of Roman’s main goals is to improve scientists’ understanding of dark matter and dark energy. The telescope will create the most detailed 3D map of the universe so far. Its main survey will take more than a year and will cover more than two billion galaxies.

Scientists believe the universe began with the Big Bang around 13.8 billion years ago and has continued to expand ever since. In 1998, scientists discovered that this expansion was accelerating. They proposed the existence of an invisible force called dark energy to explain the acceleration.

The universe contains ordinary matter, dark matter and dark energy. Ordinary matter includes stars, planets, gas, dust and other familiar material. It makes up about 5 per cent of the universe. Dark matter, which scientists detect through its gravitational effects on galaxies and stars, may account for around 27 per cent. Dark energy may make up the remaining 68 per cent.

Roman will measure the effects of dark matter’s gravity and dark energy’s influence across the universe. NASA expects these observations to bring scientists closer to understanding two of the universe’s biggest mysteries.

The telescope will also carry out a major search for exoplanets, which are planets located outside our solar system. Scientists expect Roman to discover thousands of new exoplanets. The mission could also provide the first statistical survey of planetary systems that resemble our own.

"One of the most exciting aspects of Roman is its discovery potential. Historically, major astronomical observatories have often made their most important breakthroughs in areas that scientists did not anticipate before launch," cosmologist Mustapha Ishak of the University of Texas at Dallas, a member of Roman's scientific collaboration, told Reuters.

The telescope’s launch also marks an important moment for a project that faced funding challenges. During both his first and second terms, President Donald Trump’s administration sought to reduce or eliminate funding for Roman. Congress continued to support the project and preserved its funding.

NASA said Roman launched nine months earlier than originally scheduled. The telescope is now beginning its journey to its distant orbital destination, where it will spend years surveying the universe and studying the forces and objects that shape it.