NASA Begins New Deployable Solar Array Tech Demo on Pathfinder Spacecraft

A test image of Earth taken by NASA’s Pathfinder Technology Demonstrator-4’s onboard camera. The camera will capture images of the Lightweight Integrated Solar Array and anTenna upon deployment.

NASA

NASA recently evaluated initial flight data and imagery from Pathfinder Technology Demonstrator-4 (PTD-4), confirming proper checkout of the spacecraft’s systems including its on-board electronics as well as the payload’s support systems such as the small onboard camera. Shown above is a test image of Earth taken by the payload camera, shortly after PTD-4 reached orbit. This camera will continue photographing the technology demonstration during the mission. 

Payload operations are now underway for the primary objective of the PTD-4 mission – the demonstration of a new power and communications technology for future spacecraft. The payload, a deployable solar array with an integrated antenna called the Lightweight Integrated Solar Array and anTenna, or LISA-T, has initiated deployment of its central boom structure. The boom supports four solar power and communication arrays, also called petals. Releasing the central boom pushes the still-stowed petals nearly three feet (one meter) away from the spacecraft bus. The mission team currently is working through an initial challenge to get LISA-T’s central boom to fully extend before unfolding the petals and beginning its power generation and communication operations.

Small spacecraft on deep space missions require more electrical power than what is currently offered by existing technology. The four-petal solar array of LISA-T is a thin-film solar array that offers lower mass, lower stowed volume, and three times more power per mass and volume allocation than current solar arrays. The in-orbit technology demonstration includes deployment, operation, and environmental survivability of the thin-film solar array.  

“The LISA-T experiment is an opportunity for NASA and the small spacecraft community to advance the packaging, deployment, and operation of thin-film, fully flexible solar and antenna arrays in space. The thin-film arrays will vastly improve power generation and communication capabilities throughout many different mission applications,” said Dr. John Carr, deputy center chief technologist at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “These capabilities are critical for achieving higher value science alongside the exploration of deep space with small spacecraft.”

The Pathfinder Technology Demonstration series of missions leverages a commercial platform which serves to test innovative technologies to  increase the capability of small spacecraft. Deploying LISA-T’s thin solar array in the harsh environment of space presents inherent challenges such as deploying large highly flexible non-metallic structures with high area to mass ratios. Performing experiments such as LISA-T on a smaller, lower-cost spacecraft allows NASA the opportunity to take manageable risk with high probability of great return. The LISA-T experiment aims to enable future deep space missions with the ability to acquire and communicate data through improved power generation and communication capabilities on the same integrated array.

The PTD-4 small spacecraft is hosting the in-orbit technology demonstration called LISA-T. The PTD-4 spacecraft deployed into low Earth orbit from SpaceX’s Transporter-11 rocket which launched from Space Launch Complex 4E at Vandenberg Space Force Base in California on Aug. 16. NASA’s Marshall Space Flight Center in Huntsville, Alabama designed and built the LISA-T technology as well as LISA-T’s supporting avionics system. NASA’s Small Spacecraft Technology program, based at NASA’s Ames Research Center in California’s Silicon Valley and led by the agency’s Space Technology Mission Directorate, funds and manages the PTD-4 mission as well as the overall Pathfinder Technology Demonstration mission series. Terran Orbital Corporation of Irvine, California, developed and built the PTD-4 spacecraft bus, named Triumph.

Learn more about NASA’s LISA-T technology: 

NASA teams are testing a key technology demonstration known as LISA-T, short for the Lightweight Integrated Solar Array and anTenna. It’s a super compact, stowable, thin-film solar array that when fully deployed in space, offers both a power generation and communication capability for small spacecraft. LISA-T’s orbital flight test is part of the Pathfinder Technology Demonstrator series of missions. To travel farther into deep space, small spacecraft require more electrical power than what is currently available through existing technology. LISA-T aims to answer that demand and would offer small spacecraft access to power without compromising mass or volume. Watch this video to learn more about the spacecraft, its deployment, and the possibilities from John Carr, deputy center chief technologist at NASA’s Marshall Space Flight Center in Huntsville, Alabama. 

By: Gianine Figliozzi 

Source: NASA Begins New Deployable Solar Array Tech Demo on Pathfinder Spacecraft - NASA  

Webb images nearest super-Jupiter, opening a new window to exoplanet research - UNIVERSE

Only a point of light is visible on the JWST/MIRI images. Nevertheless, the initial analysis suggests the presence of a gaseous planet that may have properties similar to Jupiter. Credit: T. Müller (MPIA/HdA)

Using the James Webb Space Telescope (JWST), an MPIA-led team of astronomers imaged a new exoplanet that orbits a star in the nearby triple system Epsilon Indi. The planet is a cold super-Jupiter exhibiting a temperature of around 0 degrees Celsius and a wide orbit comparable to that of Neptune around the sun.

This measurement was only possible thanks to JWST's unprecedented imaging capabilities in the thermal infrared. It exemplifies the potential of finding many more such planets similar to Jupiter in mass, temperature, and orbit. Studying them will improve our knowledge of how gas giants form and evolve in time.

"We were excited when we realized we had imaged this new planet," said Elisabeth Matthews, a researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. She is the main author of the underlying research article published in the journal Nature.

"To our surprise, the bright spot that appeared in our MIRI images did not match the position we were expecting for the planet," Matthews points out. "Previous studies had correctly identified a planet in this system but underestimated this super-Jupiter gas giant's mass and orbital separation." With the help of JWST, the team was able to set the record straight. 

The gas-giant exoplanet Epsilon Indi Ab imaged using the MIRI instrument on NASA’s Webb telescope. A star symbol marks the location of the host star, whose light has been blocked by MIRI’s coronagraph, resulting in the dark circle with a dashed white line. The planet is to the left of the star. Credit: NASA, ESA, CSA, STScI, E. Matthews (Max Planck Institute for Astronomy)

This detection is quite unusual in several respects. It shows the first exoplanet imaged with JWST that had not already been imaged from the ground and is much colder than the gas planets JWST has studied so far. An 'image' means that the planet appears as a bright dot on the images and thus represents direct evidence. The transit and radial velocity methods are indirect evidence, as the planet only reveals itself through its mediated effect.

JWST observations update previous measurements

The planet revolves around the main component of the nearby triple star system, Epsilon Indi, or Eps Ind for short. Astronomical labeling conventions assign the label Eps Ind A to that primary star, a red dwarf star a little smaller and cooler than the sun. To construct the planet's name, a "b" is appended, resulting in the designation Eps Ind Ab.

This zoom video begins with a wide-angle view of the sky centered on the star Eps Ind A. It ends with an image of Eps Ind Ab obtained with the MIRI imager of the JWST. Credit: T. Müller (MPIA/HdA), E. Matthews (MPIA)

The new JWST data are consistent with a super-Jupiter having a mass six times that of Jupiter in the solar system. Eps Ind Ab orbits its host star on an eccentric, elliptical orbit whose farthest separation from Eps Ind A should range between 20 and 40 astronomical units.

One astronomical unit is the mean distance between Earth and the sun, approximately 150 million kilometers. The new values differ considerably from earlier studies, which is why the team chose to call this a "new" planet.

Cool planets, hot science

Only a few cold gas-giant planets orbiting solar-age stars are known to date, and these have all been inferred indirectly from radial velocity measurements. By imaging and taking spectra of the planets, astronomers can study their atmospheres and trace the evolution of planetary systems compared to computational models.

Studying planets in fully settled planetary systems helps tie up loose ends concerning the late stages of planetary evolution and refine our general understanding of planet formation and evolution.

The recent observations lead the way to finding many more of these cold gas-giant planets. These will allow astronomers to study a new class of exoplanets and compare them to the solar system gas giants.

The inserts show cropped versions of the MIRI images obtained at mid-infrared wavelengths 10.65 (left) and 15.55 micrometers (right), which depict the area around the star Eps Ind A, whose position is indicated by star symbols. A coronagraph blocks the light from the star that would outshine both images. Instead, a new object becomes visible to the top left. This source is the exoplanet Eps Ind Ab. The background was obtained from the AllWISE sky survey. Credit: T. Müller (MPIA/HdA), E. Matthews (MPIA)

How to detect cold gas planets

However, these planets are hard to find using the classical detection methods. Planets far from their host stars are typically very cold, unlike the hot Jupiters that circle their stars at separations of only a few stellar radii. Wide orbits are highly unlikely to be aligned along the line of sight to produce a transit signal. In addition, measuring their signals with the radial-velocity method is challenging when only a small section of the orbit can be monitored.

Earlier studies attempted to investigate a giant planet orbiting Eps Ind A using radial velocity measurements. However, extrapolating a small part of the orbit led to incorrect conclusions about the planet's properties. After all, Eps Ind Ab needs around 200 years to orbit its star. Observations over a few years are insufficient to determine the orbit with high precision.

Therefore, the team around Matthews devised a different approach. They wanted to take a picture of the known planet using a method commonly known as direct imaging. Since exoplanet host stars are so bright, they outshine any other nearby object. Regular cameras would be overwhelmed by the blinding starlight.

For this reason, the team employed JWST's MIRI (Mid-Infrared Instrument) camera equipped with a coronagraph. This light-blocking mask covers the star like an artificial eclipse. Another advantage is Eps Ind's proximity to Earth, which is only 12 light-years. The smaller the distance to the star, the larger the separation between two objects appears in an image, providing a better chance of mitigating the host star's interference. MIRI was the perfect choice because it observes in the thermal or mid-infrared, where cold objects shine brightly.

What do we know about Eps Ind Ab?

"We discovered a signal in our data that did not match the expected exoplanet," says Matthews. The point of light in the image was not in the predicted location. "But the planet still appeared to be a giant planet," adds Matthews. However, before being able to make such an assessment, the astronomers had to exclude the signal was coming from a background source unrelated to Eps Ind A.

"It is always hard to be certain, but from the data, it seemed quite unlikely the signal was coming from an extragalactic background source," explains Leindert Boogaard, another MPIA scientist and a co-author of the research article.

Indeed, while browsing astronomical databases for other observations of Eps Ind, the team came across imaging data from 2019 obtained with the VISIR infrared camera attached to the European Southern Observatory's (ESO) Very Large Telescope (VLT). After re-analyzing the images, the team found a faint object precisely at the position where it should be if the source imaged with JWST belonged to the star Eps Ind A.

The scientists also attempted to understand the exoplanet atmosphere based on the available images of the planet in three colors: two from JWST/MIRI and one from VLT/VISIR. Eps Ind Ab is fainter than expected at short wavelengths. This could indicate substantial amounts of heavy elements, particularly carbon, which builds molecules such as methane, carbon dioxide, and carbon monoxide, commonly found in gas-giant planets. Alternatively, it might indicate that the planet has a cloudy atmosphere. However, more work is needed to reach a final conclusion.

Plans and prospects

This work is only a first step towards characterizing Eps Ind Ab. "Our next goal is to obtain spectra which provide us a detailed fingerprint of the planet's climatology and chemical composition," says Thomas Henning, Emeritus Director at MPIA, co-PI of the MIRI instrument, and a co-author of the underlying article.

"In the long run, we hope to also observe other nearby planetary systems to hunt for cold gas giants that may have escaped detection," says Matthews. "Such a survey would serve as the basis for a better understanding of how gas planets form and evolve." 

by Max Planck Society

Source: Webb images nearest super-Jupiter, opening a new window to exoplanet research (phys.org)