JAXA, the Japanese space agency, is preparing to launch two different space missions from one rocket: a new X-ray telescope to spy on some of the hottest places in our universe, and a small experimental robotic moon lander.
The telescope is called X-ray Imaging and Spectroscopy Mission, or XRISM for short (pronounced like the word “chrism”). The lunar mission is called 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 Eastern time (it will be 9:26 am Monday in Japan). JAXA provides a livestream in both Japanese and English to the agency YouTube channel starting around 7:55 pm Eastern time.
SLIM’s trip to the moon makes time tight: There are only a few minutes each day when Earth’s orientation is just right for the spacecraft to land on a trajectory that will put it in lunar orbit. Because of this, JAXA has a launch window until September 15, in case any liftoff delays cause the mission to miss its launch window.
What is XRISM?
It’s a telescope the size of a bus. JAXA is collaborating with NASA on the mission, with additional participation from the European Space Agency. XRISM will study cosmic X-rays, which unlike other wavelengths of light can only be seen from above the Earth’s atmosphere, which protects us from harmful radiation.
XRISM will use state-of-the-art spectroscopy to measure changes in the brightness of objects in the sky at different wavelengths. This data will reveal information about the motion and chemistry of some of the most intense cosmic locales, such as the material swirling around black holes, the blistering plasma that permeates galaxy clusters and the remnants of exploding massive stars.
A key XRISM tool is Resolve, an instrument that will collect spectroscopic data with greater resolution than Earth-orbiting X-ray observatories. Resolve must be cooled to just a fraction above absolute zero to measure small temperature changes when X-rays hit the surface of the instrument.
A second instrument named Xtend will work simultaneously to image the cosmos with a resolution comparable to the way our eyes would see it if we had X-ray vision. As Resolve zooms in, Xtend zooms out, giving scientists complementary views of both X-ray sources over a larger area.
SLIM is a compact robotic moon lander without astronauts on board. It was about the size of a small food truck and weighed more than 1,500 pounds at launch.
The lander’s mission is not scientific. Instead, it is to demonstrate a pinpoint navigation system, which aims to be set down within about the length of a football field of a target landing site. Developing better landing technology will allow future spacecraft to get closer to rugged terrain of scientific interest.
Where will XRISM and SLIM go?
The space telescope will be placed in an orbit about 350 miles above Earth. Once there, the researchers will spend the next few months turning on the instruments and running tests on their performance. Science operations will begin in January, and the first results from this data are expected in about a year.
You’ll have to be patient with SLIM on its journey to the Shioli crater on the near side of the moon. The spacecraft will take a long, circuitous journey of at least four months that requires less propellant. SLIM will take several months to reach lunar orbit, then spend a month circling the moon before attempting to plunge to the surface.
