If All Goes Well, Spacex Will Be Launching a Brand New Space Telescope This Sunday

The scope is named for a former NASA chief of astronomy. Liftoff is set for 7:26 a.m. EDT (1126 GMT) from a NASA pad in Cape Canaveral, Florida... The company will launch Roman into space atop a Falcon Heavy rocket from Launch Complex 39A at NASA's Kennedy Space Center in Florida. A launch livestream will begin about one hour before liftoff.

If all doesn't go well Sunday, the company will have another chance to fly on Monday. So what's new about the Roman Space Telescope? The mirror is the same size as the one that was inside the Hubble Telescope but it's designed to cover a much wider field of view.

This description is a bit nerdy but interesting if you've ever owned a telescope. Both Hubble and Roman are reflecting telescopes. They use curved mirrors instead of lenses to collect and "bend" light to their various instruments.

Hubble is a Ritchey-Chrétien Cassegrain telescope that uses two hyperbolic mirrors to direct light to its instruments. Hubble’s large primary mirror sends incoming light to its secondary mirror that is centered directly above the primary mirror. The secondary mirror guides that light back to the primary mirror where it passes through a hole in the center and to Hubble’s scientific instruments, located behind the mirror.

Such Cassegrain designs offer a long focal length (the length of the path that incoming light takes to come into focus) in a relatively compact package by "folding" the light path back and forth. The longer the focal length relative to the diameter of the main or primary mirror, the higher the magnification and depth of field. Roman's design is similar to Hubble's, but it uses three curved mirrors instead of two.

Its mirrors are shaped to a precise surface curve that gives the telescope a focal length that is roughly three times shorter than Hubble’s. The shorter the focal length relative to the diameter of the main or primary mirror, the wider the field of view. Roman’s Three-Mirror Anastigmat design achieves better optical performance over a significantly wider field of view compared to Hubble’s design. Both Hubble and Roman have the same size primary mirror (7.9 feet or 2.4 meters wide), but thanks to newer technologies, Roman’s primary mirror is more than four times lighter — 410 pounds (186 kilograms) compared to Hubble’s hefty 1,825 pounds (828 kilograms)... Although both primary mirrors are the same size, Roman has a much shorter focal length than Hubble, helping its Wide Field Instrument achieve a view that is 100 times larger.

That broader vista gives Roman the ability to survey large swaths of sky in a short time. With more than three decades of observations, Hubble has only seen one-tenth of one percent of the sky. During its first five years, Roman will image 50 times as much sky as Hubble captured in 30 years.

One of the benefits of the new design should be the ability to survey the entire Milky Way in a month. Another goal of the telescope is to spend a month surveying all the stars in the Milky Way galaxy. Julie McEnery is Roman's project scientist.

She says even though Roman has broadly the same sensitivity and sharpness of vision as the currently orbiting Hubble Space Telescope, its design lets it do things much faster. That one month of observations to survey our Milky Way galaxy would take about a century with Hubble, says McEnery. It will also allow us to identify lots of new extrasolar planets.

One professor eager to get his hands on Roman data is Scott Gauti at The Ohio State University. Along with colleagues, Gauti developed a technique for detecting planets around distant stars.