Sentinel-1A Satellite Takes A Direct Hit From Millimetre Size Particle

Sentinel-1 satellite, the first satellite to be launched as part of the ESA/EC's Copernicus program. Credit: ESA/ATG medialab

One of the worst things that can happen during an orbital mission is an impact. Near-Earth orbit is literally filled with debris and particulate matter that moves at very high speeds. At worst, a collision with even the smallest object can have catastrophic consequences. At best, it can delay a mission as technicians on the ground try to determine the damage and correct for it.

This was the case when, on August 23rd, the European Space Agency’s Sentinel-1A satellite was hit by a particle while it orbited the Earth. And after several days of reviewing the data from on-board cameras, ground controllers have determined what the culprit was, identified the affected area, and concluded that it has not interrupted the satellite’s operations.

The Sentinel-1A mission was the first satellite to be launched as part of the ESA’s Copernicus program – which is the worlds largest single earth observation program to date. Since it was deployed in 2014, Sentinel-1A has been monitoring Earth using its C-band Synthetic Aperture Radar, which allows for crystal clear images regardless of weather or light conditions.

In addition to tracking oil spills and mapping sea ice, the satellite has also been monitoring the movement of land surfaces. Recently, it provided invaluable insight into the earthquake in Italy that claimed at least 290 lives and caused widespread damage. These images were used by emergency aid organizations to assist in evacuations, and scientists have begun to analyze them for indications of how the quake occurred.

The first indication that something was wrong came on Tuesday, August 23rd, at 17:07 GMT (10:07 PDT, 13:07 EDT), when controllers noted a small power reduction. At the time, the satellite was at an altitude of 700 km, and slight changes in it’s orientation and orbit were also noticed.

After conducting a preliminary investigation, the operations team at the ESA’s control center hypothesized that the satellite’s solar wing had suffered from an impact with a tiny object. After reviewing footage from the on-board cameras, they spotted a 40 cm hole in one of the solar panels, which was consistent with the impact of a fragment measuring less than 5 mm in size.

However, the power loss was not sufficient to interrupt operations, and the ESA was quick to allay fears that this would result in any interruptions of the Sentinel-1A‘s mission. They also indicated that the object’s small size prevented them from advanced warning.

As Holger Krag – Head of the Space Debris Office at ESA’s establishment in Darmstadt, Germany – said in an agency press release:

“Such hits, caused by particles of millimeter size, are not unexpected. These very small objects are not trackable from the ground, because only objects greater than about 5 cm can usually be tracked and, thus, avoided by maneuvering the satellites. In this case, assuming the change in attitude and the orbit of the satellite at impact, the typical speed of such a fragment, plus additional parameters, our first estimates indicate that the size of the particle was of a few millimeters.

While it is not clear if the object came from a spent rocket or dead satellite, or was merely a tiny clump of rock, Krag indicated that they are determined to find out. “Analysis continues to obtain indications on whether the origin of the object was natural or man-made,” he said. “The pictures of the affected area show a diameter of roughly 40 cm created on the solar array structure, confirming an impact from the back side, as suggested by the satellite’s attitude rate readings.”

In the meantime, the ESA expects that Sentinel-1A will be back online shortly and doing the job for which it was intended. Beyond monitoring land movements, land use, and oil spills, Sentinel-1A also provides up-to-date information in order to help relief workers around the world respond to natural disasters and humanitarian crises.

The Sentinel-1 satellites, part of the European Union’s Copernicus Program, are operated by ESA on behalf of the European Commission.

Further Reading: Sentinel-1

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DSCOVR Captures EPIC Views of the March 2016 Eclipse

The Moon's shadow is cast across Indonesia in this view from the DSCOVR spacecraft, March 9, 2016. (Courtesy of the DSCOVR EPIC team.)

On March 8, 2016 (March 9 local time) the Moon briefly blocked the light from the Sun in what was the only total solar eclipse of the year. The event was visible across portions of southeast Asia, Indonesia, and Micronesia, and was observed by both skywatchers on the ground in person and those watching live online around the world. While to most the view was of a silhouetted Moon slowly carving away the disk of the Sun before totality revealed a shimmering corona, the view from space looking back at Earth showed the Moon’s dark shadow passing over islands, clouds, and sea.

The picture above was acquired by NASA’s EPIC (Earth Polychromatic Imaging Camera) instrument on board the DSCOVR spacecraft, operated by NOAA. It’s one of twelve images captured during the course of the eclipse from DSCOVR’s position at L1, 1.6 million km (nearly 1 million miles) away.

Read more: What Are Lagrange Points?

Launched Feb. 11, 2015, DSCOVR observes both Earth and incoming space weather from the Sun, providing up to an hour of early warning of solar storm activity. Its location gives it a view of a constantly-illuminated Earth, since DSCOVR is always positioned between it and the Sun.

Watch an animation of the Moon’s shadow traveling northeast across the Pacific here, and for more images of the March 2016 total eclipse (captured from the ground) check out this article by David Dickinson.

The next solar eclipse in 2016 will be on September 1, and will be a partial/annular eclipse visible from Africa and the Indian Ocean. The next total solar eclipse will occur on Aug. 21, 2017, during which the path of totality will cross the United States from coast to coast.

Source: NASA’s Earth Observatory

Note: The March 2016 eclipse was also captured by Japan’s Himawari-8 geostationary weather satellite; watch the sequence from that spacecraft below:

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Russian Crowdfunded Satellite May Soon Become Brightest “Star” in the Sky

Illustration of the “Beacon” inflating from its canister after reaching orbit. The Mayak Project used the Russian version of Kickstarter called Boomstarter to fund the project. Credit: / Mayak Project

We may soon look up and see a satellite brighter than the space station and even Venus gliding across the night sky if a Russian crowdfunding effort succeeds. An enthusiastic team of students from Moscow University of Mechanical Engineering are using Boomstarter, the Russian equivalent of Kickstarter, to raise the money needed to build and launch a pyramid-shaped satellite made of highly reflective material they’re calling Mayak, Russian for “Beacon”.
Young engineers at Moscow University explain the Mayak Project

To date they’ve collected more than $23,000 or 1.7 million rubles. Judging from the video, the team has built the canister that would hold the satellite (folded up inside) and performed a high-altitude test using a balloon. If funding is secured, Beacon is scheduled to launch on a Soyuz-2 rocket from the Baikonur Cosmodrome in the second quarter of this year.

Once in orbit, Beacon will inflate into a pyramid with a surface area of 172 square feet (16 square meters). Made of reflective metallized film 20 times thinner than a human hair, the satellite is expected to become the brightest man-made object in orbit ever. That title is currently held by the International Space Station which can shine as brightly as magnitude -3 or about three times fainter than Venus. The brightest satellites, the Iridiums, can flare to magnitude -8 (as bright as the crescent moon) but only for a few seconds before fading back to invisibility. They form a “constellation” of  some 66 satellites that provide data and voice communications.

A concurrently-developed mobile app would allow users to know when Beacon would pass over a particular location. The students hope to achieve more than just track a bright, moving light across the sky. According to their website, the goal of the project is the “popularization of astronautics and space research in Russia, as well as improving the attractiveness of science and technology education among young people.” They want to show that almost anyone can build and send a spacecraft into orbit, not just corporations and governments.

Further, the students hope to test aerodynamic braking in the atmosphere and find out more about the density of air at orbital altitudes. Interested donors can give anywhere from 300 rubles (about $5) up 300,000 ($4,000). The more money, the more access you’ll have to the group and news of the satellite’s progress; the top donor will get invited to watch the launch on-site.

Once finished with the Mayak Project, the team wants to built another version that uses that atmosphere for braking its speed and returning it — and future satellites — safely back to Earth without the need for retro-rockets.

I think all these goals are worthy, and I admire the students’ enthusiasm. I only hope that satellite launching doesn’t become so cheap and popular that we end up lighting up the night sky even further. What do you think?

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