Skylab 4 Recovery Ends Program

The crewmen of the third and final manned Skylab mission relax on the USS New Orleans, prime recovery ship for their mission, about an hour after their Command Module splashed down at 10:17 a.m. (CDT), Feb. 8, 1974. The splashdown, which occurred 176 statute miles from San Diego, ended 84 record-setting days of flight activity aboard the Skylab space station cluster in Earth orbit.

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Gary Daines

NASA’s New Experimental Antenna Tracks Deep Space Laser

Capable of receiving both radio frequency and optical signals, the DSN’s hybrid antenna has tracked and decoded the downlink laser from DSOC, aboard NASA’s Psyche mission.

An experimental antenna has received both radio frequency and near-infrared laser signals from NASA’s Psyche spacecraft as it travels through deep space. This shows it’s possible for the giant dish antennas of NASA’s Deep Space Network (DSN), which communicate with spacecraft via radio waves, to be retrofitted for optical, or laser, communications.

By packing more data into transmissions, optical communication will enable new space exploration capabilities while supporting the DSN as demand on the network grows.

The 34-meter (112-foot) radio-frequency-optical-hybrid antenna, called Deep Space Station 13, has tracked the downlink laser from NASA’s Deep Space Optical Communications (DSOC) technology demonstration since November 2023. The tech demo’s flight laser transceiver is riding with the agency’s Psyche spacecraft, which launched on Oct. 13, 2023.

The hybrid antenna is located at the DSN’s Goldstone Deep Space Communications Complex, near Barstow, California, and isn’t part of the DSOC experiment. The DSN, DSOC, and Psyche are managed by NASA’s Jet Propulsion Laboratory in Southern California.

“Our hybrid antenna has been able to successfully and reliably lock onto and track the DSOC downlink since shortly after the tech demo launched,” said Amy Smith, DSN deputy manager at JPL. “It also received Psyche’s radio frequency signal, so we have demonstrated synchronous radio and optical frequency deep space communications for the first time.”

In late 2023, the hybrid antenna downlinked data from 20 million miles (32 million kilometers) away at a rate of 15.63 megabits per second – about 40 times faster than radio frequency communications at that distance. On Jan. 1, 2024, the antenna downlinked a team photograph that had been uploaded to DSOC before Psyche’s launch.

Two for One

In order to detect the laser’s photons (quantum particles of light), seven ultra-precise segmented mirrors were attached to the inside of the hybrid antenna’s curved surface. Resembling the hexagonal mirrors of NASA’s James Webb Space Telescope, these segments mimic the light-collecting aperture of a 3.3-foot (1-meter) aperture telescope. As the laser photons arrive at the antenna, each mirror reflects the photons and precisely redirects them into a high-exposure camera attached to the antenna’s subreflector suspended above the center of the dish.

The laser signal collected by the camera is then transmitted through optical fiber that feeds into a cryogenically cooled semiconducting nanowire single photon detector. Designed and built by JPL’s Microdevices Laboratory, the detector is identical to the one used at Caltech’s Palomar Observatory, in San Diego County, California, which acts as DSOC’s downlink ground station.

“It’s a high-tolerance optical system built on a 34-meter flexible structure,” said Barzia Tehrani, communications ground systems deputy manager and delivery manager for the hybrid antenna at JPL. “We use a system of mirrors, precise sensors, and cameras to actively align and direct laser from deep space into a fiber reaching the detector.”

Tehrani hopes the antenna will be sensitive enough to detect the laser signal sent from Mars at its farthest point from Earth (2 ½ times the distance from the Sun to Earth). Psyche will be at that distance in June on its way to the main asteroid belt between Mars and Jupiter to investigate the metal-rich asteroid Psyche.

The seven-segment reflector on the antenna is a proof of concept for a scaled-up and more powerful version with 64 segments – the equivalent of a 26-foot (8-meter) aperture telescope – that could be used in the future.

An Infrastructure Solution

DSOC is paving the way for higher-data-rate communications capable of transmitting complex scientific information, video, and high-definition imagery in support of humanity’s next giant leap: sending humans to Mars. The tech demo recently streamed the first ultra-high-definition video from deep space at record-setting bitrates.

Retrofitting radio frequency antennas with optical terminals and constructing purpose-built hybrid antennas could be a solution to the current lack of a dedicated optical ground infrastructure. The DSN has 14 dishes distributed across facilities in California, Madrid, and Canberra, Australia. Hybrid antennas could rely on optical communications to receive high volumes of data and use radio frequencies for less bandwidth-intensive data, such as telemetry (health and positional information).

“For decades, we have been adding new radio frequencies to the DSN’s giant antennas located around the globe, so the most feasible next step is to include optical frequencies,” said Tehrani. “We can have one asset doing two things at the same time; converting our communication roads into highways and saving time, money, and resources.”

More About the Mission

DSOC is the latest in a series of optical communication demonstrations funded by NASA’s Technology Demonstration Missions (TDM) program and the agency’s Space Communications and Navigation (SCaN) program. JPL, a division of Caltech in Pasadena, California, manages DSOC for TDM within NASA’s Space Technology Mission Directorate and SCaN within the agency’s Space Operations Mission Directorate.

For more about NASA’s optical communications projects, visit:

https://www.nasa.gov/lasercomms/

News Media Contact

Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-2649
ian.j.oneill@jpl.nasa.gov

2024-012

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Anthony Greicius

Telescopes Show the Milky Way’s Black Hole is Ready for a Kick

This artist’s illustration depicts the findings of a new study about the supermassive black hole at the center of our galaxy called Sagittarius A* (abbreviated as Sgr A*). As reported in our latest press release, this result found that Sgr A* is spinning so quickly that it is warping spacetime — that is, time and the three dimensions of space — so that it can look more like a football.

These results were made with NASA’s Chandra X-ray Observatory and the NSF’s Karl G. Jansky Very Large Array (VLA). A team of researchers applied a new method that uses X-ray and radio data to determine how quickly Sgr A* is spinning based on how material is flowing towards and away from the black hole. They found Sgr A* is spinning with an angular velocity that is about 60% of the maximum possible value, and with an angular momentum of about 90% of the maximum possible value.

Black holes have two fundamental properties: their mass (how much they weigh) and their spin (how quickly they rotate). Determining either of these two values tells scientists a great deal about any black hole and how it behaves. In the past, astronomers made several other estimates of Sgr A*’s rotation speed using different techniques, with results ranging from Sgr A* not spinning at all to it spinning at almost the maximum rate.

The new study suggests that Sgr A* is, in fact, spinning very rapidly, which causes the spacetime around it to be squashed down. The illustration shows a cross-section of Sgr A* and material swirling around it in a disk. The black sphere in the center represents the so-called event horizon of the black hole, the point of no return from which nothing, not even light, can escape.

Looking at the spinning black hole from the side, as depicted in this illustration, the surrounding spacetime is shaped like a football. The faster the spin the flatter the football.

The yellow-orange material to either side represents gas swirling around Sgr A*. This material inevitably plunges towards the black hole and crosses the event horizon once it falls inside the football shape. The area inside the football shape but outside the event horizon is therefore depicted as a cavity. The blue blobs show jets firing away from the poles of the spinning black hole. Looking down on the black hole from the top, along the barrel of the jet, spacetime is a circular shape.

A black hole’s spin can act as an important source of energy. Spinning supermassive black holes produce collimated outflows such as jets when their spin energy is extracted, which requires that there is at least some matter in the vicinity of the black hole. Because of limited fuel around Sgr A*, this black hole has been relatively quiet in recent millennia with relatively weak jets. This work, however, shows that this could change if the amount of material in the vicinity of Sgr A* increases.

To determine the spin of Sgr A*, the authors used an empirically based technique referred to as the “outflow method” that details the relationship between the spin of the black hole and its mass, the properties of the matter near the black hole, and the outflow properties. The collimated outflow produces the radio waves, while the disk of gas surrounding the black hole is responsible for the X-ray emission. Using this method, the researchers combined data from Chandra and the VLA with an independent estimate of the black hole’s mass from other telescopes to constrain the black hole’s spin.

The paper describing these results led by Ruth Daly (Penn State University) is published in the January 2024 issue of the Monthly Notices of the Royal Astronomical Society and appears online at https://ui.adsabs.harvard.edu/abs/2024MNRAS.527..428D/abstract. The other authors are Biny Sebastian (University of Manitoba, Canada), Megan Donahue (Michigan State University), Christopher O’Dea (University of Manitoba), Daryl Haggard (McGill University) and Anan Lu (McGill University).

NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.

Read more from NASA’s Chandra X-ray Observatory.

For more Chandra images, multimedia and related materials, visit:

https://www.nasa.gov/mission/chandra-x-ray-observatory/

Visual Description:

This artist’s illustration shows a cross-section of Sagittarius A*, pronounced as “SAJ-ee-TARE-ee-us A-star”, the supermassive black hole near the center of our Milky Way galaxy.

In the middle of the image, the spinning, circular black hole is presented from the side in black. The shape of the surrounding spacetime, pictured in shades of dark yellow, looks as though it has been squashed down, thus resembling the shape of an American football. The swirling gas that surrounds Sagittarius A* is presented on either side of the black hole, within a rectangular-shaped dotted line, indicating the representation is a cross-section view.

The background of the image contains a multitude of faint stars, peeking out from within brooding, dark red, indistinct clouds.

News Media Contact

Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998

Jonathan Deal
Marshall Space Flight Center
Huntsville, Ala.
256-544-0034

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Lee Mohon

NASA’s Hubble Traces ‘String of Pearls’ Star Clusters in Galaxy Collisions

Contrary to what you might think, galaxy collisions do not destroy stars. In fact, the rough-and-tumble dynamics trigger new generations of stars, and presumably accompanying planets.

Now NASA’s Hubble Space Telescope has homed in on 12 interacting galaxies that have long, tadpole-like tidal tails of gas, dust, and a plethora of stars. Hubble’s exquisite sharpness and sensitivity to ultraviolet light have uncovered 425 clusters of newborn stars along these tails, looking like strings of holiday lights. Each cluster contains as many as 1 million blue, newborn stars.

Clusters in tidal tails have been known about for decades. When galaxies interact, gravitational tidal forces pull out long streamers of gas and dust. Two popular examples are the Antennae and Mice galaxies with their long, narrow, finger-like projections.

A team of astronomers used a combination of new observations and archival data to get ages and masses of tidal tail star clusters. They found that these clusters are very young – only 10 million years old. And they seem to be forming at the same rate along tails stretching for thousands of light-years.

“It’s a surprise to see lots of the young objects in the tails. It tells us a lot about cluster formation efficiency,” said lead author Michael Rodruck of Randolph-Macon College in Ashland, Virginia. “With tidal tails, you will build up new generations of stars that otherwise might not have existed.”

The tails look like they are taking a galaxy’s spiral arm and stretching it out into space. The exterior part of the arm gets pulled like taffy from the gravitational tug-of-war between a pair of interacting galaxies.

Before the mergers, the galaxies were rich in dusty clouds of molecular hydrogen that simply may have remained inert. But the clouds got jostled and bumped into each other during the encounters. This compressed the hydrogen to the point where it precipitated a firestorm of star birth.

The fate of these strung-out star clusters is uncertain. They may stay gravitationally intact and evolve into globular star clusters – like those that orbit outside the plane of our Milky Way galaxy. Or they may disperse to form a halo of stars around their host galaxy, or get cast off to become wandering intergalactic stars.

This string-of-pearls star formation may have been more common in the early universe when galaxies collided with each other more frequently. These nearby galaxies observed by Hubble are a proxy for what happened long ago, and therefore are laboratories for looking into the distant past.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

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Media Contacts:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

Ray Villard
Space Telescope Science Institute, Baltimore, MD

Science Contact:

Michael Rodruck
Randolph-Macon College, Ashland, VA

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