NASA Astronomy Picture of the Day

Nov 30, 2023

Artemis 1: Flight Day 13

On flight day 13 (November 28, 2022) of the Artemis I mission, the Orion spacecraft reached its maximum distance from its home world. Over 430,000 kilometers from Earth in a distant retrograde orbit, Orion surpassed the record for most distant spacecraft designed to carry humans. That record was previously set in 1970 during the Apollo 13 mission to the Moon. Both Earth and Moon are in the same field of view in this video frame from Orion on Artemis I mission flight day 13. The planet and its large natural satellite even appear about the same apparent size from the uncrewed spacecraft's perspective.

https://apod.nasa.gov/apod/astropix.html?

NASA Orbiter Snaps Stunning Views of Mars Horizon

Nov 28, 2023

The Odyssey orbiter captured clouds and dust in the Red Planet’s skies, along with one of its two tiny moons.

Astronauts often react with awe when they see the curvature of the Earth below the International Space Station. Now Mars scientists are getting a taste of what that’s like, thanks to NASA’s 2001 Mars Odyssey orbiter, which completed its 22nd year at the Red Planet last month.

The spacecraft captured a series of panoramic images that showcases the curving Martian landscape below gauzy layers of clouds and dust. Stitched end to end, the 10 images offer not only a fresh, and stunning, view of Mars, but also one that will help scientists gain new insights into the Martian atmosphere.

The spacecraft took the images in May from an altitude of about 250 miles (400 kilometers) – the same altitude at which the space station flies above Earth.

“If there were astronauts in orbit over Mars, this is the perspective they would have,” said Jonathon Hill of Arizona State University, operations lead for Odyssey’s camera, called the Thermal Emission Imaging System, or THEMIS. “No Mars spacecraft has ever had this kind of view before.”

How It Was Done

The reason why the view is so uncommon is because of the challenges involved in creating it. Engineers at NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission, and Lockheed Martin Space, which built Odyssey and co-leads day-to-day operations, spent three months planning the THEMIS observations. The infrared camera’s sensitivity to warmth enables it to map ice, rock, sand, and dust, along with temperature changes, on the planet’s surface.

It can also measure how much water ice or dust is in the atmosphere, but only in a narrow column directly below the spacecraft. That’s because THEMIS is fixed in place on the orbiter; it usually points straight down.

The mission wanted a more expansive view of the atmosphere. Seeing where those layers of water-ice clouds and dust are in relation to each other – whether there’s one layer or several stacked on top of each other – helps scientists improve models of Mars’ atmosphere.

“I think of it as viewing a cross-section, a slice through the atmosphere,” said Jeffrey Plaut, Odyssey’s project scientist at JPL. “There’s a lot of detail you can’t see from above, which is how THEMIS normally makes these measurements.

https://www.jpl.nasa.gov/news/nasa-orbiter-snaps-stunning-views-of-mars-horizon

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Webb Telescope: A prominent protostar in Perseus

NOV 28, 2023

This new Picture of the Month from the NASA/ESA/CSA James Webb Space Telescope reveals intricate details of the Herbig Haro object 797 (HH 797). Herbig-Haro objects are luminous regions surrounding newborn stars (known as protostars), and are formed when stellar winds or jets of gas spewing from these newborn stars form shockwaves colliding with nearby gas and dust at high speeds. HH 797, which dominates the lower half of this image, is located close to the young open star cluster IC 348, which is located near the eastern edge of the Perseus dark cloud complex. The bright infrared objects in the upper portion of the image are thought to host two further protostars.

This image was captured with Webb’s Near-InfraRed Camera (NIRCam). Infrared imaging is powerful in studying newborn stars and their outflows, because the youngest stars are invariably still embedded within the gas and dust from which they are formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making Herbig-Haro objects ideal for observation with Webb’s sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen and carbon monoxide, emit infrared light that Webb can collect to visualise the structure of the outflows. NIRCam is particularly good at observing the hot (thousands of degree Celsius) molecules that are excited as a result of shocks.

Using ground-based observations, researchers have previously found that for cold molecular gas associated with HH 797, most of the red-shifted gas (moving away from us) is found to the south (bottom right), while the blue-shifted gas (moving towards us) is to the north (bottom left). A gradient was also found across the outflow, such that at a given distance from the young central star, the velocity of the gas near the eastern edge of the jet is more red-shifted than that of the gas on the western edge. Astronomers in the past thought this was due to the outflow’s rotation. In this higher resolution Webb image, however, we can see that what was thought to be one outflow is in fact made up of two almost parallel outflows with their own separate series of shocks (which explains the velocity asymmetries). The source, located in the small dark region (bottom right of center), and already known from previous observations, is therefore not a single but a double star. Each star is producing its own dramatic outflow. Other outflows are also seen in this image, including one from the protostar in the top right of center along with its illuminated cavity walls.

HH 797 resides directly north of HH 211 (separated by approximately 30 arcseconds), which was the feature of a Webb image release in September 2023.

https://www.nasa.gov/missions/webb/webb-telescope-a-prominent-protostar-in-perseus/

For the first time, we’re seeing views of China’s entire space station

11/29/2023

China released new pictures of its Tiangong space station Tuesday as Chinese astronauts and space officials made a public relations visit to Hong Kong. These images, taken about a month ago, show the Tiangong complex in its fully assembled configuration with three modules staffed by three crew members.

A departing crew of three astronauts captured the new panoramic views of the Tiangong station in low-Earth orbit October 30, shortly after departing the outpost to head for Earth at the end of a six-month mission. These are the first views showing the Tiangong station after China completed assembling its three main modules last year.

The Tianhe core module is at the center of the complex. It launched in April 2021 with crew accommodations and life support systems for astronauts. Two experiment modules, named Wentian and Mengtian, launched in 2022. The first team of Chinese astronauts arrived at the station in June 2021, and Tiangong has been permanently staffed by rotating three-person crews since June 2022.

One of these crews closed out their six-month stint on the Tiangong station October 30. Their Shenzhou 16 ferry ship backed away from Tiangong, then autonomously flew a circle around the outpost as the astronauts floated near windows on their spacecraft with cameras "to complete a panoramic image of the space station assembly with the Earth as the background," the China Manned Space Agency said.

Tiangong's power-generating solar arrays dominate the views captured by the Shenzhou 16 astronauts. These solar panels span more than half the length of a football field, end to end.

It turns out China may not be finished constructing the Tiangong station. In remarks last month, officials outlined plans to add three more pressurized compartments to expand China's space station in the coming years.

Tiangong, which means "heavenly palace," will become a hub for experiments, technology demonstrations, spacecraft assembly, and satellite servicing, said Zhang Qiao, a researcher at the China Academy of Space Technology (CAST). CAST is part of the web of state-owned contractors that build rockets and spacecraft for China's space program.

“We will build a 180 (metric) tons, six-module assembly in the future," Zhang said at the International Astronautical Congress last month.

In its current configuration, Tiangong has a mass of about 69 metric tons, not including visiting crew and cargo vehicles. That's about one-sixth the mass of the larger International Space Station, created under a partnership between the United States, Russia, Europe, Japan, and Canada. Chinese officials claim their space station, though significantly smaller than the ISS, has nearly as much capacity for scientific experiments.

"This indicates that the Tiangong space station has high application support efficiency," Chinese space engineers wrote in a paper published earlier this year in Space: Science & Technology, an open access journal and sister publication of the journal Science.

Now, China is making a longer-term commitment to the Tiangong program, with a blueprint for doubling the size of the space station. Chinese space officials originally said the space station would operate for 10 years. Last month, officials said the lifetime would now extend to 15 years or longer.

This means the Tiangong space station will continue operating at least until the mid-2030s, several years after the planned decommissioning of the International Space Station in 2030, more than 30 years after the launch of the oldest ISS module. NASA's strategy is to partner with commercial industry to develop a smaller space station to replace the ISS in low-Earth orbit. The idea is that a commercial space station would be cheaper to operate than the ISS, and NASA and other government space agencies could buy access to the privately owned outpost for astronauts and scientific experiments.

https://arstechnica.com/space/2023/11/china-says-its-space-station-seen-in-new-photos-is-poised-for-growth/