Japan will launch the XRISM telescope and SLIM Moon Lander: how to watch

Japan’s space agency JAXA is preparing to launch two very different space missions using a single rocket: a new X-ray telescope that will spy on some of the hottest parts of our world, and a small experimental robotic lander on the surface of the moon.

called a telescope The task of X-ray imaging and spectroscopyOr XRISM for short (pronounced like “chrism”). The lunar mission is called the Smart Lander for Investigating Moon, or SLIM. Here’s what you need to know about the launch.

When is the launch and how can I watch it?

XRISM and SLIM are expected to launch from an H-IIA rocket from Japan’s Tanegashima Space Center on Sunday at 8:26 PM ET (it will be Monday 9:26 AM in Japan). The Japan Aerospace Exploration Agency provides live broadcasts in both Japanese and English on the agency’s website YouTube channel Starting around 7:55 p.m. ET.

SLIM’s trip to the moon makes timing tight: There are only a few minutes each day when the Earth’s orientation is just right for the spacecraft to take a trajectory that puts it into lunar orbit. Thus, the Japan Aerospace Exploration Agency has a launch window reserved until September 15, in case any launch delay causes the mission to miss its launch window.

What is XRISM?

It’s a bus-sized telescope. The Japan Aerospace Exploration Agency and NASA are collaborating on this mission, with additional participation from the European Space Agency. XRISM will study cosmic X-rays, which unlike other wavelengths of light can only be detected above Earth’s atmosphere, protecting us from harmful radiation.

XRISM will use state-of-the-art spectroscopy to measure changes in the brightness of celestial bodies at different wavelengths. This data will reveal information about the motion and chemistry of some of the cosmic most extreme locations, such as material orbiting black holes, the burning plasma that permeates galaxy clusters, and the remnants of massive exploding stars.

One of the main instruments aboard XRISM is Resolve, an instrument that will collect spectral data with much greater precision than Earth-orbiting X-ray observatories. The solution must be cooled to only a fraction above absolute zero in order to measure small changes in temperature when the X-rays hit the surface of the instrument.

A second instrument called Xtend will work simultaneously to image the universe with a resolution similar to the way our eyes might perceive it if we had X-ray vision. As Resolve zooms in, Xtend will zoom out, giving scientists complementary views of the same X-ray sources over a larger area.

SLIM is a small-scale robotic lunar lander with no astronauts on board. It’s about the size of a small food truck and weighs over 1,500 pounds at launch.

The landing mission is not primarily scientific. Rather, it is a demonstration of a precise navigational system, intended to land about the distance of a football field at the target landing site. Developing better landing technology would enable future spacecraft to land near rough terrain of scientific interest.

Where are XRISM and SLIM headed?

The space telescope will be put into orbit about 350 miles above Earth. Once there, the researchers will spend the next few months operating the devices and running tests of their performance. Science operations will begin in January, and initial results from this data are expected in about a year.

You’ll have to be patient with SLIM on its journey toward Xiuli Crater on the near side of the Moon. The spacecraft will take a long indirect flight of at least four months and require less propellant. SLIM will take several months to reach lunar orbit, then spend a month orbiting the moon before attempting a surface landing.