January 18, 2020

Soyuz launches Italian radar satellite, ESA exoplanet telescope


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A Soyuz ST-A rocket lifted off at 0854:20 (3:54:20 a.m. EST) Wednesday from the Guiana Space Center in South America. Credit: ESA/CNES/Arianespace – Photo Optique Video du CSG

A package of five satellites, including an Italian radar reconnaissance craft and a European Space Agency exoplanet science probe, soared into orbit Wednesday from French Guiana aboard a Russian-made Soyuz rocket.

The satellites lifted off at 0854:20 GMT (3:54:20 a.m. EST) Wednesday from the Guiana Space Center on the northeastern coast of South America. A Soyuz ST-A booster guided the payloads northward from French Guiana, and a Fregat upper stage took over less than 10 minutes after liftoff for a series of six engine burns to inject the satellites into three distinct polar sun-synchronous orbits.

The orbital ballet included deployments of satellites at three different altitudes.

The first payload released from the Fregat upper stage around 23 minutes after liftoff was Italy’s first COSMO-SkyMed Second Generation, or CSG 1, radar surveillance satellite. The 4,861-pound (2,205-kilogram) satellite, built by Thales Alenia Space, will provide high-resolution, all-weather radar imagery for military and civilian applications.

The Fregat targeted a 384-mile-high (619-kilometer) orbit to deploy the CSG 1 spacecraft, then performed additional engine firings to reach a higher 435-mile-high (700-kilometer) altitude for separation of the European Space Agency’s CHEOPS spacecraft. CHEOPS will peer at bright stars known to host exoplanets, helping astronomers learn more about the sizes of alien worlds beyond our solar system.

Then the rocket’s upper stage lowered its altitude below 500 kilometers (310 kilometers) for separation of three European CubeSats, ranging in side from a toaster oven to a small suitcase.

The OPS-SAT CubeSat from the European Space Agency is a free-for-use, in-orbit testbed for new software, applications and techniques in satellite control.

The EyeSat CubeSat from the French space agency, CNES, will observe the zodiacal light and image the Milky Way.

The French ANGELS CubeSat carries an Argos data collection payload to relay data from remote weather stations and buoys.

The Soyuz launch Wednesday was delayed 24 hours this week to resolve a technical issue with the launch vehicle. The mission closes out the 2019 launch calendar for Arianespace, which launched nine times this year across its fleet of Ariane 5, Soyuz and Vega rockets. One of the Vega missions failed in its attempt to deliver a United Arab Emirates spy satellite to orbit.

“For our ninth and last launch of the year, success is here for our customers and our partners,” said Stephane Israel, Arianespace’s CEO. “Congratulations to all of them. this success shows Arianespace’s ability to deliver for European institutions and to orbit innovative small satellites.”

Artist’s concept of the COSMO-SkyMed Second Generation satellite. Credit: ASI

The CSG 1 spacecraft carries a radar instrument designed to observe Earth during day and night passes, capturing imagery with a resolution better than a meter, or about 3.3 feet. CSG 1 is the first of two new second-generation Italian radar observation satellites ensure no data gaps from COSMO-SkyMed fleet as the four first-generation satellites move beyond their original five-year design lives.

The COSMO-SkyMed system’s first four satellites launched from California on United Launch Alliance Delta 2 rockets from 2007 through 2010.

The COSMO-SkyMed radar reconnaissance network, intended for military and civilian use, is funded by the Italian Space Agency, or ASI, the Italian Ministry of Defense and the Italian Ministry of Education, University and Research.

Featuring X-band synthetic aperture radars, the COSMO-SkyMed satellites collect imagery by sending radar signals toward Earth, then collecting the beams reflected off the surface. The reflected signal contains information about surface topography and roughness, yielding an image that can show vegetation, water surfaces, roads, bridges, airplanes and ships, among other features.

The CSG 1 satellite will unfurl its radar antenna array for testing before entering service next year.

“COSMO-SkyMed Second Generation confirms the global coverage of the Earth, operating in any atmospheric and light condition, night and day, and provides, compared to the first generation, an increased number of images, improvement in quality, additional capabilities — for example, full polarization — and a high response time,” said Francesco Longo, head of the programs office at ASI.

A second COSMO-SkyMed Second Generation satellite could launch as soon as late 2020 on a Vega C rocket from French Guiana.

Designed for seven-year missions, the two second-generation COSMO-SkyMed satellites carry improved radar imaging systems, and “will provide our customers with new and more advanced observation capability in terms of image quality, resolution, information content, pointing agility and system response time,” said Giampiero Di Paolo, head of the observation and navigation domain at Thales Alenia Space in Italy.

The Italian radar satellites, imaging in X-band, work in concert with Argentina’s SAOCOM L-band radar observation satellites, the first of which launched in 2018. A second SAOCOM radar surveillance craft is scheduled to launch in March from Cape Canaveral on a SpaceX Falcon 9 rocket.

Artist’s illustration of the CHEOPS spacecraft observing an exoplanet transiting in front of its parent star. Credit: ESA/ATG medialab

Designed to build upon discoveries made by previous pioneering exoplanet telescopes — like NASA’s Kepler mission — the European Space Agency’s Characterizing Exoplanet Satellite, or CHEOPS, mission was injected into orbit some 435 miles (700 kilometers) above Earth Wednesday with a small but ultra-sensitive telescope looking at faraway stars.

“We are extremely relieved,” said Günther Hasinger, ESA’s director of science, in remarks after Wednesday’s launch. “We now know that CHEOPS is working. All systems are green. telemetry is stable, temperatures are fine, power voltages are fine, so everything is good to go.”

CHEOPS will be capable of registering tiny changes in the brightness of stars as planets block their light from reaching the telescope. This way of observing exoplanets is called the transit method, and it’s been used by Kepler, NASA’s TESS observatory, and the French space agency’s CoRoT mission to discover planets around other stars.

Astronomers designed CHEOPS to follow up on discoveries made by other telescopes.

“What makes CHEOPS quite special to all the other transit missions so far is that CHEOPS is not really a discovery mission,” said Willy Benz, the mission’s principal investigator from the University of Bern in Switzerland. “It’s a follow-up. We will be looking at one system at a time, and not trying to discover thousands of others.”

“The idea is that we know now several thousands of these exoplanets,” Benz said. “We are more interested slowly toward characterizing them with precision, knowing what they’re made of and their temperature, and so on and so forth.”

Astronomers can determine the mass of an exoplanet through a technique called the radial velocity method, in which telescopes can detect the wobble of a star caused by the pull of gravity from a smaller planetary companion. The amplitude of the wobble can tell scientists about the planet’s mass.

Combining the size information from CHEOPS with mass estimates obtained through other telescopes can yield significant insights into exoplanets, Benz said.

“By measuring the radius and by knowing the mass through radial velocity, we can place these different planets and try to figure out what they’re made of, whether they’re rocky planets, whether they’re a gas ball, an icy world, or the like,” he said. “You need to have pretty small error bars if you want to say anything meaningful about this, and this is why we need precision measurements.”

Didier Queloz, a Swiss astronomer at the University of Cambridge, won the 2019 Nobel Prize in Physics with Michel Mayor for their work in discovering the first exoplanet orbiting a sun-like star in 1995.

Queloz is chair of the CHEOPS science team. “We started this project more than 10 years ago, and now we’re in the sky,” he said.

“The field has just exploded,” he said Wednesday. “There are just thousands of exoplanets. There are a lot of planets known to be transiting, which means the planet goes right in front of the star, and that’s the technique that we’re using for the CHEOPS mission.

“We have so many planets, so different,” Queloz said. “We have these super-Earths, mini-Neptunes. We don’t really understand all these systems. So that’s the purpose of CHEOPS, providing new data, very precise data, to understand a bit better.”

CHEOPS can help identify prime targets for additional observations by future missions, such as the James Webb Space Telescope scheduled for launch in 2021.

“We want to look at atmospheres, following planets in their orbits around the star, we may want to see if a planet has moons, rings, and so on, and we want to provide the best targets for the very large facilities under construction or going into orbit like JWST,” Benz said.

David Ehrenreich, mission scientist for the CHEOPS consortium at the University of Geneva, said future large telescopes likes JWST and the Extremely Large Telescope in Chile will be under high demand.

“We think that in the coming years there will be far too many very interesting small planets to characterize with powerful facilties than observing time available on these over-booked facilities,” Ehrenreich said. “So it will become extremely important to down-select the golden target — the very best of these targets — so we could go and spend a lot of time with Hubble, with James Webb, and with the ELT on the ground.

“CHEOPS is going to be a key in this process by confirming and obtaining the first step characterization of these many targets, and determining which one we should look for,” Ehrenreich said.

Artist’s illustration of CHEOPS with its telescope door open. Credit: ESA/ATG medialab

ESA’s new exoplanet telescope will observe about 300 targets during its three-and-a-half-year primary mission, according to Ehrenreich.

CHEOPS is small. It stands 4.9 feet (1.5 meters) tall and stretches 5.2 feet (1.6 meters) wide, with a fixed solar array to generate electricity. The satellite was built in Spain by Airbus Defense and Space and weighs 601 pounds (273 kilograms), according to the mission’s press kit.

The budget for the CHEOPS mission is also relatively modest, barely rising above the $110 million (100 million-euro) mark. ESA funded about half the mission’s cost, including the procurement of the spacecraft bus and launch services. A consortium of 11 European nations, led by Switzerland and Spain, contributed funding for the rest of the mission’s cost.

ESA selected CHEOPS as the agency’s first S-class, or small, science mission in 2012. The S-class missions join a roster of more expensive medium and large missions in ESA’s space science portfolio.

“It’s a mission to deliver world-class exoplanet science, and specifically what we’re doing is measuring sizes of known exoplanets using the techniques of high-precision transit photometry,” said Kate Isaak, CHEOPS project scientist at ESA.

“It follows on from CoRoT, from Kepler and from TESS, and it’s the first in a series of three missions from ESA that are dedicated to exoplanet science,” Isaak said. “CHEOPS will provide us with key information to understand the structure of small planets, and how they form and evolve. This will be an essential step in a worldwide endeavor … to search for exoplanets like our own Earth.”

The choice of a low-altitude orbit for CHEOPS helped save money, officials said.

“Being in a low Earth orbit has the advantage that it’s relatively cheap,” Benz said. “It doesn’t require too much fancy communication, but it has disadvantages. The Earth hides part of the sky. You’re flying through radiation belts, which cause problems in your electronics and in your detectors.”

CHEOPS will fly in an orbit that hugs the terminator, or the boundary between the day and night sides of Earth.

“The idea is to always observe stars that are located over the dark side of the Earth,” Benz said.

CHEOPS hosts a 12-inch (30-centimeter) telescope designed to help astronomers measure the sizes of planets orbiting other stars. “You may wonder what’s the big fuss in a 30-centimeter telescope. You can almost buy it in a supermarket,” Benz said.

The CHEOPS telescope is tuned to detect faint changes in light, with optics designed to eliminate stray light from Earth, the moon, and other bright nearby objects.

The sensitivity of the CHEOPS telescope — with optics from Italy, a focal plane module from Germany, detectors from the United Kingdom, and a baffle and cover assembly from Belgium — will allow astronomers to measure the sizes of exoplanets as small Earth, according to Benz.

“If an Earth passes in front of the sun, as seen from a distance, you will see 100 ppm, 100 parts per million change in the light,” Benz said. “If Jupiter is passing, you will see 1 percent, so it’s much bigger. This is .01 percent … You need to go to space to see these kinds of changes. It’s the amplitude of these changes in the light that determines then how accurate your mission has to measure the light.”

With multiple observations of the same transiting planet, CHEOPS could measure the size an exoplanet with a precision of 10 percent, according to Ravit Helled, a CHEOPS contributor from the University of Zurich.

Astronomers are particularly interested in a class of exoplanets bigger than Earth but smaller than Neptune.

“There is a large population of exoplanets of intermediate masses and radii, and they are very common in the galaxy,” Helled said. “And these are planets that we don’t know how to characterize so much … With CHEOPS, we will be able to hopefully characterize more of these intermediate-class planets.”

Artist’s concept of the Eye-Sat and ANGELS CubeSats in orbit. Credit: CNES

Arianespace’s next mission is scheduled for launch Jan. 16, when an Ariane 5 rocket will loft two communications satellites into orbit for Eutelsat and the Indian Space Research Organization. The next Soyuz launch from French Guiana is scheduled in early March with the Falcon Eye 2 optical spy satellite for the United Arab Emirates.

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Follow Stephen Clark on Twitter: @StephenClark1.


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