Space News & Blog Articles

Wow, what a beauty! While we’ve all turned our attentions to the new James Webb Space Telescope, this image proves Hubble has still has got it where it counts.  

This new image from the Hubble Space Telescope shows the heart of the globular cluster NGC 6638 in the constellation Sagittarius. This star-studded cluster contains tens of thousands to millions of stars, all tightly bound together by gravity. Globular clusters have a higher concentration of stars towards their centers, and this observation highlights that density.

This image was taken with Hubble’s Wide Field Camera 3 and the Advanced Camera for Surveys.

Like so many things that Hubble has observed since it launched to space in 1989, this venerable telescope has revolutionized the study of globular clusters. With its instruments and clear vision above Earth’s atmosphere, Hubble has been able to study what kind of stars make up globular clusters, how they evolve, and the role of gravity in these dense systems.

Globular clusters are found in nearly all galaxies. They are the largest and most massive type of star clusters, and they tend to be older and denser than open clusters. From Hubble, we’ve learned that the  typical distance between stars in a globular cluster is about one light year. But at the central core of a cluster where the concentration of stars is the highest, the distance there between stars averages about a third of a light year, or thirteen times closer than Proxima Centauri is to our Sun.

While NASA’s much-lauded Space Launch System stands ready for its maiden flight later this month with the goal of sending astronauts back to the Moon in the next few years, our gazes once again turn to the stars as we continue to ask the question that has plagued humankind since time immemorial: Are we alone? While there are several solar system locales that we can choose from to conduct our search for life beyond Earth, to include Mars and Saturn’s moons, Titan and Enceladus, one planetary body orbiting the largest planet in the solar system has peaked the interest of scientists since the 1970s.

Jupiter’s second Galilean Moon, Europa, with its interior ocean, predominantly crater-less surface, and crisscrosses of cracks and ridges spanning entire hemispheres, makes it one of the most fascinating planetary bodies ever observed. These unique geologic features are possibly indicative of liquid water traveling to the surface from its deep ocean, making Europa a hot spot for the exploration and study of life beyond Earth, also known as astrobiology.

False color mosaic of Europa taken by NASA’s Galileo spacecraft. (Credit: NASA/JPL-Caltech/SETI Institute)

“Europa may be one of the few accessible places whether life could originate and persist,” says Dr. Michael Manga, a geophysicist and Professor in the Department of Earth and Planetary Science at UC Berkeley. “Its evolution and dynamics are fascinating, some similarities but also fundamental differences from Earth.”

Scientists hypothesize that Europa’s icy outer shell is 15 to 25 kilometers (10 to 15 miles) thick that floats on an ocean 60 to 150 kilometers (40 to 100 miles) deep. While there is strong evidence that Saturn’s moon, Enceladus, also has a interior ocean, Europa’s ocean is believed to potentially house double the amount of water as all of Earth’s oceans combined, despite Europa being only a quarter of Earth’s diameter.

The OSIRIS-REx spacecraft conducted a two-year reconnaissance and sample collection at the asteroid Bennu, providing crucial data about the 500-meter-wide potentially hazardous rubble pile/space rock. When OSIRIS-REx arrived on Dec. 3, 2018, it needed some tricky navigation and precise maneuvers to make the mission work.

Experts at NASA Goddard’s Scientific Visualization Studio created an amazing visualization of the path the spacecraft took during its investigations. A short film called “A Web Around Asteroid Bennu” highlights the complexity of the mission, and the film is being shown at the SIGGRAPH computer graphics conference in Vancouver, British Columbia, Canada, a festival honoring standout works of computer animated storytelling.

Other films in the festival include Disney’s “Encanto” and Warner Brothers’ “The Batman.”

Data visualizer Kel Elkins compiled the data for the film, which shows the web-like flight path for OSIRIS-REx, as well as the touch-and-go, or TAG, maneuver to collect the sample from the asteroid’s surface.

“I started working with the trajectory data in 2015,” Elkins said. “And when you first see an image of all the different maneuvers it looks like a rat’s nest. But it was really exciting to see these complicated maneuvers in 3D space.”

Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious “stuff” permeates the universe. In particular, it exists in halos surrounding most galaxies. The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That’s pretty much the standard view of dark matter and its influence on galaxies. However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?

Finding Perturbed Dwarf Galaxies

In the so-called “Standard Model” of cosmology, shells or halos of dark matter protect galaxies from the gravitational influence of nearby galactic neighbors. However, when astronomers at the University of Bonn and Saint Andrews in Scotland looked in the nearby Fornax Cluster, which lies some 62 million light-years away from us, they saw something strange. It contains a number of dwarf galaxies with distorted, perturbed shapes. This is odd, especially if they should be surrounded by dark matter halos.

The Fornax Galaxy Cluster, which contains distorted dwarf galaxies in its collection. Image Credit: ESO

Let’s take a quick look at dwarf galaxies. They’re small and faint and usually found riding along in galaxy clusters or near much larger companions. The Milky Way Galaxy has a coterie of dwarf galaxies around it,. It is, in fact, cannibalizing ones such as the Sagittarius Dwarf Spheroidal. Interestingly, recent studies show that at least one of the dwarf galaxies near ours, an ancient one called Tucana II, has an astoundingly massive dark matter halo.

So, what’s happening in Fornax that’s different? There, dwarf galaxies could be “disturbed” by gravitational tides from nearby larger ones in the cluster. Tides happen when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth when the Moon pulls more strongly on the side of Earth that faces it.