{"id":12505,"date":"2020-04-28T21:42:45","date_gmt":"2020-04-28T13:42:45","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/spacex-to-debut-satellite-dimming-sunshade-on-starlink-launch-next-month\/"},"modified":"2020-04-28T21:42:45","modified_gmt":"2020-04-28T13:42:45","slug":"spacex-to-debut-satellite-dimming-sunshade-on-starlink-launch-next-month","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/spacex-to-debut-satellite-dimming-sunshade-on-starlink-launch-next-month\/","title":{"rendered":"SpaceX to debut satellite-dimming sunshade on Starlink launch next month"},"content":{"rendered":"
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SpaceX plans to debut a new sunshade structure on its future Starlink satellites. Credit: SpaceX<\/figcaption><\/figure>\n

A new sunshade, or visor, designed to reduce the brightness of SpaceX\u2019s Starlink broadband Internet satellites will debut on the company\u2019s next launch, a measure intended to alleviate astronomers\u2019 concerns about impacts on observations through ground-based telescopes, SpaceX founder Elon Musk said Monday.<\/p>\n

Beginning with the next launch of Starlink satellites \u2014 scheduled as soon as May 7 from Cape Canaveral \u2014 SpaceX will try out a new light-blocking panel to make the spacecraft less visible to skywatchers and astronomers.<\/p>\n

\u201cWe have a radio-transparent foam that will deploy nearly upon the satellite being released (from the rocket),\u201d Musk said Monday in a virtual meeting of the National Academies\u2019 Decadal Survey on Astronomy and Astrophysics 2020 panel, a committee charged with setting the top priorities for U.S. astronomy for the next decade.<\/p>\n

Musk said the new material will block sunlight from reaching the satellites\u2019 antennas, comparing it to a sun visor in a car\u2019s windshield. Reflected sunlight at dawn and dusk is what makes the satellites visible from the ground.<\/p>\n

The sunshade is transparent to radio signals. SpaceX has nicknamed the new Starlink satellite design \u201cVisorSat.\u201d<\/p>\n

On seven launches since last May, SpaceX has deployed 420 Starlink satellites to begin building out the Starlink network. The satellites are designed to provide global broadband Internet service, and SpaceX eventually plans to launch thousands of the quarter-ton, flat-panel data relay stations to orbits below an altitude of about 354 miles (570 kilometers).<\/p>\n

\u201cUsing our low orbital altitude and flat satellite geometry to our advantage, we designed an RF-transparent deployable visor for the satellite that blocks the light from reaching most of the satellite body and all of the diffuse parts of the main body,\u201d SpaceX wrote in an update posted on the company\u2019s website this week. \u201cThis visor lays flat on the chassis during launch and deploys during satellite separation from Falcon 9. The visor prevents light from reflecting off of the diffuse antennas by blocking the light from reaching the antennas altogether.\u201d<\/p>\n

SpaceX says that every future Starlink satellite will be fitted with the sun visor beginning with a subsequent launch in June.<\/p>\n

Five Falcon 9 rocket launches so far this year have carried 300 Starlink satellites into orbit \u2014 60 at a time \u2014 most recently on April 22. The next Falcon 9 launch for the Starlink network is set for May 7 at approximately 7:30 a.m. EDT (1130 GMT).<\/p>\n

The sunshade is the latest change SpaceX has introduced on Starlink satellites in response to complaints from astronomers about the network\u2019s impacts on observations from ground-based telescopes.<\/p>\n

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This 333-second exposure taken last year by the Dark Energy Camera on the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory shows 19 streaks attributed to Starlink satellites passing through the camera\u2019s field-of-view shortly after their launch Nov. 11 from Cape Canaveral. Credit: NSF\u2019s National Optical-Infrared Astronomy Research Laboratory\/NSF\/AURA\/CTIO\/DELVE<\/figcaption><\/figure>\n

The first 60 Starlink satellites launched last May were much brighter than SpaceX or astronomers anticipated, prompting a series of discussions between the aerospace company and the astronomy community.<\/p>\n

SpaceX launched a satellite with a darker coating in January, and astronomers noticed an improvement. SpaceX said last month that preliminary data indicated a \u201cnotable reduction\u201d in the brightness of that satellite, which has been dubbed \u201cDarkSat.\u201d<\/p>\n

\u201cThe darkening that they did on DarkSat is about a factor of two-and-a-half fainter \u2014 so about 1 magnitude in astronomical units \u2014 and it\u2019s still visible to the unaided eye under excellent conditions,\u201d said Pat Seitzer, an astronomer and orbital debris expert at the University of Michigan.. \u201cThat is you\u2019re a person with great vision sitting on top of a mountaintop faraway from the city lights.\u201d<\/p>\n

But the darker coating has drawbacks, SpaceX said. Black surfaces in space get hot, so the company is moving forward with the sun visor solution instead.<\/p>\n

\u201cThis avoids thermal issues due to black paint, and is expected to be darker than DarkSat since it will block all light from reaching the white diffuse antennas,\u201d SpaceX said.<\/p>\n

The Starlink satellites are brightest soon after a launch, when they are flying at an altitude of around 200 miles (300 kilometers). Once deployed from the Falcon 9 rocket, the spacecraft unfurl their solar array wings to generate electricity, then activate krypton ion thrusters to begin climbing into their higher operational orbit some 341 miles (550 kilometers) above Earth.<\/p>\n

SpaceX commands the satellites to fly in a special attitude, or orientation, during the orbit-raising maneuvers. This minimizes drag on the satellites.<\/p>\n

\u201cThis low-drag and thrusting flight configuration resembles an open book, where the solar array is laid out flat in front of the vehicle,\u201d SpaceX said. \u201cWhen Starlink satellites are orbit-raising, they roll to a limited extent about the velocity vector for power generation, always keeping the cross sectional area minimized while keeping the antennas facing Earth enough to stay in contact with the ground stations.\u201d<\/p>\n

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Credit: SpaceX<\/figcaption><\/figure>\n

After the satellites reach their operational orbit, SpaceX flies the spacecraft in a different configuration called the \u201cshark-fin\u201d attitude. In this orientation, the solar panel points away from the Earth.<\/p>\n

When the satellites are in the \u201copen book\u201d configuration at lower altitudes, sunlight reflects off the craft\u2019s solar arrays, making them more visible from the ground.<\/p>\n

The sun visor is designed to reduce brightness while the Starlink satellites are on station at their operational altitude. SpaceX is debuting a different technique to address brightness concerns during the early weeks of each satellite\u2019s life, when the spacecraft are flying closer to Earth.<\/p>\n

\u201cWe\u2019re taking several steps to reduce brightness in orbit-raising, which has definitely startled a lot of people around the world,\u201d Musk said Monday. \u201cI\u2019ve gotten quite a lot of feedback on that front. So we\u2019re changing the angles. That should be something that happens even this week \u2014 the satellites being commanded to a different angle that is less bright.\u201d<\/p>\n

\u201cWe\u2019re currently testing rolling the satellite so the vector of the sun is in-plane with the satellite body, i.e. so the satellite is knife-edge to the sun,\u201d SpaceX said. \u201cThis would reduce the light reflected onto Earth by reducing the surface area that receives light.\u201d<\/p>\n

The new roll maneuver can be implemented when the satellites are climbing to higher altitude, and when they pause in an intermediate orbit to align with their operational planes within the Starlink network.<\/p>\n

SpaceX said the new \u201corientation roll\u201d maneuver will diminish the amount of power generated by each satellite\u2019s solar panel, and reduce contact time between the spacecraft and ground controllers. The change also points star tracker cameras at the Earth and the sun, reducing the satellite\u2019s attitude knowledge, according to SpaceX.<\/p>\n

\u201cThere will be a small percentage of instances when the satellites cannot roll all the way to true knife edge to the sun due to one of the aforementioned constraints,\u201d SpaceX said. \u201cThis could result in the occasional set of Starlink satellites in the orbit raise of flight that are temporarily visible for one part of an orbit.\u201d<\/p>\n

Musk described the changes as \u201cquite simple.\u201d<\/p>\n

\u201cI think, with the benefit of hindsight, the changes seem quite simple, which is to make sure that the orientation of the satellites is not such that we\u2019re reflecting the sun,\u201d he said. \u201cAnd to either darken the specular surfaces or the white surfaces, or shade them, is really quite simple actually. It\u2019s a little bit silly in hindsight. It\u2019s not that hard.<\/p>\n

\u201cOur objectives, generally, are to make the satellites invisible to the naked eye within a week, and to minimize the impact on astronomy, especially so that we do not saturate observatory detectors and inhibit discoveries,\u201d Musk said.<\/p>\n

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Credit: SpaceX<\/figcaption><\/figure>\n

The satellites that launched without the brightness mitigations will likely be retired and will re-enter the atmosphere and burn up within three or four years, Musk said. They will be replaced with improved satellites.<\/p>\n

SpaceX has regulatory approval from the Federal Communications Commission to eventually field a fleet of up to 12,000 small Starlink broadband stations.<\/p>\n

Officials say 24 launches are needed to provide global broadband service through the Starlink service. But the company could provide an interim level of service over parts of the Earth \u2014 such as Canada and northern parts of the United States \u2014 later this year, once SpaceX has launched around 720 satellites on 12 Falcon 9 flights.<\/p>\n

Musk tweeted last week that SpaceX aims to begin private \u201cbeta testing\u201d of the Starlink service within about three months, followed by a public trial period in six months.<\/p>\n

SpaceX has modified the architecture of the Starlink network several times. Most recently, SpaceX submitted an application to the Federal Communication Commission on Friday proposing to operate more satellites in lower orbits than the FCC previously authorized.<\/p>\n

Rather than launching more than 2,800 of the Starlink satellites to higher orbits between 690 miles (1,110 kilometers) and 823 miles (1,325 kilometers) in altitude, SpaceX will instead deploy the spacecraft closer to Earth. The change allows the network to provide consumers with better Internet service, and also reduces the number of Starlink satellites that might be visible in the sky at any one time.<\/p>\n

\u201cWe think, for a lot of reasons, that 550 (kilometers) and below is the right approach for a LEO (Low Earth Orbit) broadband situation,\u201d Musk said. \u201cYour data rate is going to be four times better than say at 1,100 kilometers. That\u2019s a close approximation. It\u2019s also better for astronomy.\u201d<\/p>\n

The lower orbit also ensures atmospheric drag will cause dead satellites to re-enter the atmosphere more quickly, SpaceX said.<\/p>\n

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This diagram illustrates when the Starlink satellites are most visible, shortly after sunset and shortly before sunrise. Credit: SpaceX<\/figcaption><\/figure>\n

Musk said 20,000 to 30,000 Starlink satellites may be needed to provide the level of Internet service envisioned by SpaceX, which aims to provide connectivity to the \u201c3 or 4 percent of the least-served portion of the Earth.\u201d<\/p>\n

\u201cSo it\u2019s not a huge percentage, but it\u2019s for those that have the least service,\u201d Musk said Monday. \u201cYou do want to have probably on the order of 20,000 to 30,000 satellites, something like that. But not 200,000, I don\u2019t think.\u201d<\/p>\n

SpaceX has filed documentation with the International Telecommunication Union for up to 30,000 additional Starlink satellites beyond the 12,000 spacecraft already authorized by the FCC.<\/p>\n

It\u2019s the large number of Internet satellites planned by SpaceX and other companies, such as Amazon, that worries astronomers.<\/p>\n

\u201cSpaceX is committed to the progress of science, both in the United States and elsewhere,\u201d Musk said. \u201cSo we\u2019ll do our best to ensure that we\u2019re not going to interfere with any facilities anywhere in the world.\u201d<\/p>\n

One of the ground-based facilities most at risk of interference from the Starlink satellites is the U.S. government-funded Vera Rubin Observatory, formerly known as the Large Synoptic Survey Telescope. The observatory under construction in Chile will capture deep, wide-field images of the entire southern sky, allowing astronomers to learn more about dark energy and dark matter, and detect potentially hazardous asteroids with orbits near Earth, among other objectives.<\/p>\n

Steve Kahn, director of the Vera Rubin Observatory, said last week that SpaceX is responsive to astronomers\u2019 concerns.<\/p>\n

\u201cThey\u2019ve been quite cooperative in working with us,\u201d Kahn told Spaceflight Now in an interview.<\/p>\n

Scientists will measure the brightness of the new VisorSat spacecraft after launch to gauge the effectiveness of the sunshade. If it works as advertised, the sun visor could limit the impacts of the Starlink satellites on the Vera Rubin Observatory.<\/p>\n

Musk <\/strong><\/em>pitches astronomers on Starship\u2019s ability to launch giant space telescopes<\/strong><\/em><\/p>\n

Toward the end of Monday\u2019s virtual meeting, Musk expressed interest in building and launching a new space-based observatory using SpaceX\u2019s next-generation Starship launch vehicle.<\/p>\n

\u201cI\u2019d be pretty interested in trying to figure out how to help launch and possibly build a big satellite, a big observatory in space,\u201d Musk said. \u201cMaybe \u2026 we can get together and talk about what would be a really exciting space observatory, like a planet imager or something like that.\u201d<\/p>\n

The decadal survey panel was chartered to prioritize which space-based observatories NASA should pursue after the launch of the James Webb Space Telescope and the Wide Field Infrared Survey Telescope.<\/p>\n

\u201cI\u2019m really interested in the advancement of science, and to understand what the heck is going on in this universe,\u201d Musk said.<\/p>\n

SpaceX says from the Starlink Internet business will help fund development of the Starship. When coupled with a new first stage booster SpaceX calls the Super Heavy, the Starship will be able to loft more than 100 metric tons, or 220,000 pounds, of cargo to low Earth orbit.<\/p>\n

\u201cStarship has the capability to transport satellites, payloads, crew, and cargo to a variety of orbits and Earth, lunar, or Martian landing sites,\u201d SpaceX wrote in a Starship user\u2019s guide released last month.<\/p>\n

The Starship\u2019s payload envelope is also significantly larger than any other existing rocket. Its diameter will measure around 30 feet, or 9 meters, allowing the Starship to launch big telescopes without requiring the mirrors be folded to fit inside a payload fairing.<\/p>\n

\u201cThe launch situation has changed quite dramatically from where it was in 2010,\u201d Musk said. \u201cIt will be very much changed, I think, in even five years. I think Starship \u2026 will be flying quite soon. I think you\u2019ll see regular flights within a couple of years, and that\u2019s a very big rocket.<\/p>\n

\u201cIt allows for space telescopes to be at least transported to orbit at probably an order of magnitude lower cost than in the past,\u201d Musk said. \u201cSo that\u2019s pretty important to factor into future plans.\u201d<\/p>\n

Email the author.<\/i><\/b><\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

SpaceX plans to debut a new sunshade structure on its future Starlink satellites. Credit: SpaceX A new sunshade, or visor, designed to reduce the brightness of SpaceX\u2019s Starlink broadband Internet satellites will debut on the company\u2019s next launch, a measure intended to alleviate astronomers\u2019 concerns about impacts on observations through ground-based telescopes, SpaceX founder Elon […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[2233,1661,1690,252,2234,2076,1045,25],"class_list":["post-12505","post","type-post","status-publish","format-standard","hentry","category-news","tag-2020-astrophysics-decadal-survey","tag-astronomy","tag-astrophysics","tag-broadband","tag-darksat","tag-decadal-survey","tag-elon-musk","tag-launch"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/12505"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=12505"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/12505\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=12505"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=12505"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=12505"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}