Space News & Blog Articles

When white dwarfs go wild, their planets suffer through the resulting chaos. The evidence shows up later in and around the dying star’s atmosphere after it gobbles up planetary and cometary debris. That’s the conclusion a team of UCLA astronomers came to after studying the nearby white dwarf G238-44 in great detail. They found a case of cosmic cannibalism at this dying star, which lies about 86 light-years from Earth.

If that star were in the place of our Sun, it would ingest the remains of planets, asteroids, and comets out to the Kuiper Belt. That expansive buffet makes this stellar cannibalism act one of the most widespread ever seen.

“We have never seen both of these kinds of objects accreting onto a white dwarf at the same time,” said lead researcher Ted Johnson, a physics and astronomy graduate of UCLA. “By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact.”

An artist’s view of a white dwarf siphoning off debris from shattered worlds in its planetary system. Courtesy NASA/ESA, Joseph Olmstead (STScI)

Finding Evidence of Chaos at a Dying Star

Johnson was part of a team from UCLA, UC San Diego, and the University of Kiel in Germany working to study chemical elements detected in and around the white dwarf atmosphere. They used data from NASA’s retired Far Ultraviolet Spectroscopic Explorer, the Keck Observatory’s High-Resolution Echelle Spectrometer in Hawaii, and the Hubble Space Telescope’s Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph. The team found and measured the presence of nitrogen, oxygen, magnesium, silicon, and iron, as well as other elements.

Mapping the interior of the ice giants is difficult, to say the least. Not only are they far away and therefore harder to observe, but their constant ice cover makes it extremely hard to detect what lies underneath. So scientists must devise more ingenious ways to see what’s inside them. A team from the University of Idaho, Cal Tech, Reed College, and the University of Arizona think they might have come up with a way – to look at the structure of Neptunes’ and Uranus’ rings.

This isn’t the first technique scientists have used, though. Previous efforts have attempted to use the common technique of photometry to detect oscillations on the planet’s surface. Those oscillations can then be correlated to the density of particular parts of the planet’s interior. While the technique worked well for Jupiter, the photometry data we have of the ice giants so far have proved insufficient to determine the same density profiles. 

An alternative is using gravitational oscillations within the planet’s surface. In particular, there is a type of oscillation pattern known as a “normal mode.” This oscillation pattern happens when all parts of a system begin oscillating with the same sinusoidal frequency. And the gravitational effects of normal mode oscillations in the planet’s interior can be felt outside and reflected in the rings themselves.

It also isn’t the first time patterns in a planet’s rings have been used to calculate its internal density. Saturn has a better-understood ring system than Uranus or Neptune, the two ice giants with known ring systems. Scientists have been performing seismological analyses on the Saturnian ring system for years using data from Voyager and Cassini. The result is a better understanding of some of the normal modes of the planet’s interior and, therefore, an estimate of the makeup of the planet’s core and the rotation rate of the bulk of its material.

Neptune and Uranus each have a series of different rings, though they are not as well studied as Saturn’s. Some of those rings of which are corralled by shepherd moons. But according to the new paper, the same density reflections of resonance waves evident in Saturn’s rings are likely present in the ice giant’s ring systems as well.

When NASA sent the Mars Reconnaissance Orbiter (MRO) to the red planet in 2006, the spacecraft took an instrument with it called CRISM—Compact Reconnaissance Imaging Spectrometer for Mars. CRISM’s job is to produce maps of Mars’ surface mineralogy. It’s been an enormous success, but unfortunately, the loss of its last cryocooler in 2017 means the spectrometer can only undertake limited observations.

But CRISM is going out with a bang, creating one final image of the surface of Mars that NASA will release in batches over the next six months.

“It’s effectively a whole new data set that will fuel a second wave of discoveries about Mars’ surface composition.”

The new map will cover 86% of Mars’ surface. It’ll be 5.6 gigapixels in size and will reveal the locations of dozens of important minerals in 72 colours. Since many minerals form in the presence of water, the locations of certain minerals reveal evidence of Mars’ watery past. The new map will also help plan future missions and choose the most promising locations for rovers to visit.

We already have the first portions of the new map. The final version of the map will contain about 51,000 540-kilometre-long strips, contained in 1764 tiles. In mid-June, NASA released 48 of those tiles, and they cover five of Mars’ most scientifically interesting regions.

Northrup Grumman’s Cygnus cargo spacecraft conducted a successful reboost of the International Space Station over the past weekend, on Saturday, June 25, 2022. The Cygnus NG-17 “Piers Sellers” is the first US-based spacecraft to provide a substantial orbital adjustment to the ISS since the space shuttles retired in 2011. Russia’s Progress cargo spacecraft has been the primary source for station reboosts, attitude control, and debris avoidance maneuvers.

“This reboost of the ISS using Cygnus adds a critical capability to help maintain and support the space station,” said Steve Krein, vice president, civil and commercial space, tactical space systems, Northrop Grumman, in a press release. “It also demonstrates the enormous capability Cygnus offers the ISS and future space exploration efforts.”

Cygnus fired its gimbaled delta velocity engine for a total of 301 seconds, raising the station’s perigee by about 0.8 kilometers (1/2 mile) and its apogee by nearly 0.2 kilometers (.1 mile) for a test of “this enhanced capability for a standard service for NASA,” Northrup Grumman said.  “This Cygnus mission is the first to feature this enhanced capability as a standard service for NASA.”  

Cygnus had been docked to the ISS since February and now has departed, leaving on June 28. Back in 2018, the ninth Cygnus resupply mission conducted a test of the reboost capability by conducting a short 50 second burn of its main engine, raising the Station’s altitude by 90 meters (295 feet). The thruster firing on June 25 was actually the second attempt to raise the station’s orbit with the Cygnus NG-17, as on June 20, the maneuver was aborted after just five seconds. Northrup Grumman said the abort was triggered automatically and came as a “precautionary measure.” An investigation by engineers showed that the observed parameters were as expected and acceptable.

Having US capabilities to provide propulsion to the ISS came to the fore as an issue following Russia’s invasion of Ukraine in late February 2022. After sanctions imposed on Russia by the US and other countries who are part of the space station consortium, thinly-veiled threats by Dmitry Rogozin, the Director-General of the Russian State Space Corporation (Roscosmos) indicated that Russia might be terminating its cooperation in space; he also suggested the country might use the ISS as a weapon. The Russian news agency RIA Novosti also showed a CGI video depicting the Russian modules detaching from the ISS. Other volleys on social media from Rogozin and others made for a tense few months, but tempers seemed to have cooled lately.