A Visit to NISAR

Feb 6, 2023

Officials from NASA, the Indian Space Research Organisation (ISRO), and the Indian Embassy visit a clean room at NASA's Jet Propulsion Laboratory on Feb. 3, 2023, to view the scientific instrument payload for the NASA-ISRO Synthetic Aperture Radar (NISAR) mission.

The NISAR mission—a joint effort between NASA and ISRO—will measure changes to Earth's land ice surfaces down to fractions of an inch. Data collected by this satellite will help researchers monitor a wide range of changes critical to life on Earth in unprecedented detail.

https://www.nasa.gov/image-feature/a-visit-to-nisar

https://www.nasa.gov/feature/jpl/nasa-isro-earth-science-instruments-get-send-off-before-moving-to-india

Webb Detects Extremely Small Main Belt Asteroid

Feb 6, 2023

An asteroid roughly the size of Rome’s Colosseum — between 300 to 650 feet (100 to 200 meters) in length — has been detected by an international team of European astronomers using NASA’s James Webb Space Telescope. Their project used data from the calibration of the Mid-InfraRed Instrument (MIRI), in which the team serendipitously detected an interloping asteroid. The object is likely the smallest observed to date by Webb and may be an example of an object measuring under 0.6 miles (1 kilometer) in length within the main asteroid belt, located between Mars and Jupiter. More observations are needed to better characterize this object’s nature and properties.

“We — completely unexpectedly — detected a small asteroid in publicly available MIRI calibration observations,” explained Thomas Müller, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany. “The measurements are some of the first MIRI measurements targeting the ecliptic plane and our work suggests that many new objects will be detected with this instrument.”

These Webb observations, published in the journal Astronomy and Astrophysics, were not designed to hunt for new asteroids — in fact, they were calibration images of the main belt asteroid (10920) 1998 BC1, which astronomers discovered in 1998. The observations were conducted to test the performance of some of MIRI’s filters, but the calibration team considered them to have failed for technical reasons due to the brightness of the target and an offset telescope pointing. Despite this, the data on asteroid 10920 were used by the team to establish and test a new technique to constrain an object’s orbit and to estimate its size. The validity of the method was demonstrated for asteroid 10920 using the MIRI observations combined with data from ground-based telescopes and ESA’s Gaia mission.

In the course of the analysis of the MIRI data, the team found the smaller interloper in the same field of view. The team’s results suggest the object measures 100–200 meters, occupies a very low-inclination orbit, and was located in the inner main-belt region at the time of the Webb observations.

“Our results show that even ‘failed’ Webb observations can be scientifically useful, if you have the right mindset and a little bit of luck,” elaborated Müller. “Our detection lies in the main asteroid belt, but Webb’s incredible sensitivity made it possible to see this roughly 100-meter object at a distance of more than 100 million kilometers.”

The detection of this asteroid — which the team suspects to be the smallest observed to date by Webb and one of the smallest detected in the main belt — would, if confirmed as a new asteroid discovery, have important implications for our understanding of the formation and evolution of the solar system. Current models predict the occurrence of asteroids down to very small sizes, but small asteroids have been studied in less detail than their larger counterparts owing to the difficulty of observing these objects. Future dedicated Webb observations will allow astronomers to study asteroids smaller than 1 kilometer in size.

What’s more, this result suggests that Webb will also be able to serendipitously contribute to the detection of new asteroids. The team suspects that even short MIRI observations close to the plane of the solar system will always include a few asteroids, most of which will be unknown objects.

In order to confirm that the object detected is a newly discovered asteroid, more position data relative to background stars is required from follow-up studies to constrain the object’s orbit.

“This is a fantastic result which highlights the capabilities of MIRI to serendipitously detect a previously undetectable size of asteroid in the main belt,” concluded Bryan Holler, Webb support scientist at the Space Telescope Science Institute in Baltimore, Maryland. “Repeats of these observations are in the process of being scheduled, and we are fully expecting new asteroid interlopers in those images.”

https://www.nasa.gov/feature/goddard/2023/webb-detects-extremely-small-main-belt-asteroid

High-Gain Antenna for NASA’s Roman Mission Clears Environmental Tests

Feb 6, 2023

Engineers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, have finished testing the high-gain antenna for the Nancy Grace Roman Space Telescope. When it launches by May 2027, this NASA observatory will help unravel the secrets of dark energy and dark matter, search for and image exoplanets, and explore many topics in infrared astrophysics. Pictured above in a test chamber, the antenna will provide the primary communication link between the Roman spacecraft and the ground. It will downlink the highest data volume of any NASA astrophysics mission so far.

The antenna reflector is made of a carbon composite material that weighs very little but will still withstand the spacecraft’s wide temperature fluctuations. The dish spans 5.6 feet (1.7 meters) in diameter, standing about as tall as a refrigerator, yet only weighs 24 pounds (10.9 kilograms). Its large size will help Roman send radio signals across a million miles of intervening space to Earth. At one frequency, the dual-band antenna will receive commands and send back information about the spacecraft’s health and location. It will use another frequency to transmit a deluge of data at up to 500 megabits per second to ground stations in New Mexico, Australia, and Japan. These locations are spread out so the Roman team will consistently be able to communicate with the spacecraft.

Producing this antenna was a coordinated effort between the government and the commercial sector. NASA was responsible for the radio frequency design and fabrication of the feed assemblies. A commercial partner, Applied Aerospace Structures Corporation (AASC) in Stockton, California, was contracted for the final flight mechanical design and fabrication of the composite reflector and strut assembly. The completed antenna was delivered to NASA in December. Engineers at AASC and Goddard have extensively tested it to confirm it will operate as expected in the extreme environment of space, where it will experience a temperature range of minus 26 to 284 degrees Fahrenheit (minus 32 to 140 degrees Celsius). The team also put the antenna through vibrational testing to make sure it will withstand the spacecraft’s launch. Engineers measured the antenna’s performance in a radio-frequency anechoic test chamber, shown in the photo above. Every surface in the test chamber is covered in pyramidal foam pieces that minimize interfering reflections during testing. Next, the team will attach the antenna to the articulating boom assembly, and then electrically integrate it with Roman’s Radio Frequency Communications System.

https://www.nasa.gov/image-feature/goddard/2023/high-gain-antenna-for-nasas-roman-mission-clears-environmental-tests

https://roman.gsfc.nasa.gov/