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Crowdfunded spacecraft LightSail 2 prepares to go sailing on sunlight

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Among the many spacecraft and satellites ascending to space on Monday’s Falcon Heavy launch, the Planetary Society’s LightSail 2 may be the most interesting. If all goes well, a week from launch it will be moving through space — slowly, but surely — on nothing more than the force exerted on it by sunlight.

LightSail 2 doesn’t have solar-powered engines, or use solar energy or heat for some secondary purpose; it will literally be propelled by the physical force of photons hitting its immense shiny sail. Not solar wind, mind you — that’s a different thing altogether.

It’s an idea, explained Planetary Society CEO and acknowledged Science Guy Bill Nye said in a press call ahead of the launch, that goes back centuries.

“It really goes back to the 1600s,” he said; Kepler deduced that a force from the sun must cause comet tails and other effects, and “he speculated that brave people would one day sail the void.”

So they might, as more recent astronomers and engineers have pondered the possibility more seriously.

“I was introduced to this in the 1970s, in the disco era. I was in Carl Sagan’s astronomy class… wow, 42 years ago, and he talked about solar sailing,” Nye recalled. “I joined the Planetary Society when it was formed in 1980, and we’ve been talking about solar sails around here ever since then. It’s really a romantic notion that has tremendous practical applications; there are just a few missions that solar sails are absolutely ideal for.”

Those would primarily be long-term, medium-orbit missions where a craft needs to stay in an Earth-like orbit, but still get a little distance away from the home planet — or, in the future, long-distance missions where slow and steady acceleration from the sun or a laser would be more practical than another propulsion method.

Mission profile

The eagle-eyed among you may have spotted the “2” in the name of the mission. LightSail 2 is indeed the second of its type; the first launched in 2015, but was not planned to be anything more than a test deployment that would burn up after a week or so.

That mission had some hiccups, with the sail not deploying to its full extent and a computer glitch compromising communications with the craft. It was not meant to fly via solar sailing, and did not.

“We sent the CubeSat up, we checked out the radio, the communications, the overall electronics, and we deployed the sail and we got a picture of that deployed sail in space,” said COO Jennifer Vaughn. “That was purely a deployment test; no solar sailing took place.”

The spacecraft itself, minus the sail, of course.

But it paved the way for its successor, which will attempt this fantastical form of transportation. Other craft have done so, most notably JAXA’s IKAROS mission to Venus, which was quite a bit larger — though as LightSail 2’s creators pointed out, not nearly as efficient as their craft — and had a very different mission.

The brand new spacecraft, loaded into a 3U CubeSat enclosure — that’s about the size of a loaf of bread — is piggybacking on an Air Force payload going up to an altitude of about 720 kilometers. There it will detach and float freely for a week to get away from the rest of the payloads being released.

Once it’s safely on its own, it will fire out from its carrier craft and begin to unfurl the sail. From that loaf-sized package will emerge an expanse of reflective Mylar with an area of 32 square meters — about the size of a boxing ring.

Inside the spacecraft’s body is also what’s called a reaction wheel, which can be spun up or slowed down in order to impart the opposite force on the craft, causing it to change its attitude in space. By this method LightSail 2 will continually orient itself so that the photons striking it propel it in the desired direction, nudging it into the desired orbit.

1 HP (housefly power) engine

The thrust produced, the team explained, is very small — as you might expect. Photons have no mass, but they do (somehow) have momentum. Not a lot, to be sure, but it’s greater than zero, and that’s what counts.

“In terms of the amount of force that solar pressure is going to exert on us, it’s on the micronewton level,” said LightSail project manager Dave Spencer. “It’s very tiny compared to chemical propulsion, very small even compared to electric propulsion. But the key for solar sailing is that it’s always there.”

“I have many numbers that I love,” cut in Nye, and detailed one of them: “It’s nine micronewtons per square meter. So if you have 32 square meters you get about a hundred micronewtons. It doesn’t sound like much, but as Dave points out, it’s continuous. Once a rocket engine stops, when it runs out of fuel, it’s done. But a solar sail gets a continuous push day and night. Wait…” (He then argued with himself about whether it would experience night — it will, as you see in the image below.)

Bruce Betts, chief scientist for LightSail, chimed in as well, to make the numbers a bit more relatable: “The total force on the sail is approximately equal to the weight of a house fly on your hand on Earth.”

Yet if you added another fly every second for hours at a time, pretty soon you’ve got a really considerable amount of acceleration going on. This mission is meant to find out whether we can capture that force.

“We’re very excited about this launch,” said Nye, “because we’re going to get to a high enough altitude to get away from the atmosphere, far enough that we’ll really gonna be able to build orbital energy and take some, I hope, inspiring pictures.”

Second craft, same (mostly) as the last

The LightSail going up this week has some improvements over the last one, though overall it’s largely the same — and a relatively simple, inexpensive craft at that, the team noted. Crowdfunding and donations over the last decade have provided quite a bit of cash to pursue this project, but it still is only a small fraction of what NASA might have spent on a similar mission, Spencer pointed out.

“This mission is going to be much more robust than the previous LightSail 1, but as we said previously, it’s done by a small team,” he said. “We’ve had a very small budget relative to our NASA counterparts, probably 1/20th of the budget that a similar NASA mission would have. It’s a low-cost spacecraft.”

Annotated image of LightSail 2, courtesy of Planetary Society.

But the improvements are specifically meant to address the main problems encountered by LightSail 2’s predecessor.

Firstly, the computer inside has been upgraded to be more robust (though not radiation-hardened) and given the ability to sense faults and reboot if necessary — they won’t have to wait, as they did for LightSail 1, for a random cosmic ray to strike the computer and cause a “natural reboot.” (Yes, really.)

The deployment of the sail itself has also improved. The previous one only extended to about 90% of its full width and couldn’t be adjusted after the fact. Subsequently tests have been done, Betts told me, to exactly determine how many revolutions the motor must make to extend the sail to 100%. Not only that, but they have put markings on the extending booms or rods that will help double check how deployment has gone.

“We also have the capability on orbit, if it looks like it’s not fully extended, we can extend it a little bit more,” he said.

Once it’s all out there, it’s uncharted territory. No one has attempted to do this kind of mission, even IKAROS, which had a totally different flight profile. The team is hoping their sensors and software are up to the task — and it should be clear whether that’s the case within a few hours of unfurling the sail.

It’s still mainly an experiment, of course, and what the team learns from this they will put into any future LightSail mission they attempt, but also share it with the spaceflight community and others attempting to sail on sunlight.

“We all know each other and we all share information,” said Nye. “And it really is — I’ve said it as much as I can — it’s really exciting to be flying this thing at last. It’s almost 2020 and we’ve been talking about it for, well, for 40 years. It’s very, very cool.”

LightSail 2 will launch aboard a SpaceX Falcon Heavy no sooner than June 24th. Keep an eye on the site for the latest news and a link to the live stream when it’s almost time for takeoff.

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SpaceX reveals more Starlink info after launch of first 60 satellites

Posted by | Gadgets, hardware, orbital debris, satellite communications, Space, space internet, SpaceX, starlink, TC | No Comments

Last night’s successful Starlink launch was a big one for SpaceX — its heaviest payload ever, weighed down by 60 communications satellites that will eventually be part of a single constellation providing internet to the globe. That’s the plan, anyway — and the company pulled the curtain back a bit more after launch, revealing a few more details about the birds it just put in the air.

SpaceX and CEO Elon Musk have been extremely tight-lipped about the Starlink satellites, only dropping a few hints here and there before the launch. We know, for instance, that each satellite weighs about 500 pounds, and are a flat-panel design that maximized the amount that can fit in each payload. The launch media kit also described a “Startracker” navigation system that would allow the satellites to locate themselves and orbital debris with precision.

At the fresh new Starlink website, however, a few new details have appeared, alongside some images that provide the clearest look yet (renders, not photographs, but still) of the satellites that will soon number thousands in our skies.

In the CG representation of how the satellites will work, you get a general sense of it:

Thousands of satellites will move along their orbits simultaneously, each beaming internet to and from the surface in a given area. It’s still not clear exactly how big an area each satellite will cover, or how much redundancy will be required. But the image gives you the general idea.

The signal comes from and goes to a set of four “phased array” radio antennas. This compact, flat type of antenna can transmit in multiple directions and frequencies without moving like you see big radar dishes do. There are costs as well, but it’s a no-brainer for satellites that need to be small and only need to transmit in one general direction — down.

There’s only a single solar array, which unfolds upwards like a map (and looks pretty much like you’d expect — hence no image here). The merits of having only one are mainly related to simplicity and cost — having two gives you more power and redundancy if one fails. But if you’re going to make a few thousand of these things and replace them every couple of years, it probably doesn’t matter too much. Solar arrays are reliable standard parts now.

The krypton-powered ion thruster sounds like science fiction, but ion thrusters have actually been around for decades. They use a charge difference to shoot ions — charged molecules — out in a specific direction, imparting force in the opposite direction. Kind of like a tiny electric pea shooter that, in microgravity, pushes the person back with the momentum of the pea.

To do this it needs propellant — usually xenon, which has several (rather difficult to explain) properties that make it useful for these purposes. Krypton is the next Noble gas up the list in the table, and is similar in some ways but easier to get. Again, if you’re deploying thousands of ion engines — so far only a handful have actually flown — you want to minimize costs and exotic materials.

Lastly there is the star tracker and collision avoidance system. This isn’t very well explained by SpaceX, so we can only surmise based on what we see. The star tracker tells each satellite its attitude, or orientation in space — presumably by looking at the stars and comparing that with known variables like time of day on Earth and so on. This ties in with collision avoidance, which uses the government’s database of known space debris and can adjust course to avoid it.

How? The image on the Starlink site shows four discs at perpendicular orientations. This suggests they’re reaction wheels, which store kinetic energy and can be spun up or slowed down to impart that force on the craft, turning it as desired. Very clever little devices actually, and quite common in satellites. These would control the attitude and the thruster would give a little impulse, and the debris is avoided. The satellite can return to normal orbit shortly thereafter.

A SpaceX representative told me that the debris tracker hooks into the Air Force’s Combined Space Operations Center, where trajectories of all known space debris are tracked. These trajectories are checked against those of the satellites, and if a possible collision is detected the course changes are made, well ahead of time. This isn’t a matter of seeing a rock and dodging it, more like air traffic control.

We still don’t know a lot about the Starlink system. For instance, what do its ground stations look like? Unlike Ubiquitilink, you can’t receive a Starlink signal directly on your phone. So you’ll need a receiver, which Musk has said in the past is about the size of a pizza box. But small, large, or extra large? Where can it be mounted, and how much does it cost?

In a media briefing last week Musk described it in slightly more specific terms: “It’s like a flat disc, but unlike a, say, a DirecTV satellite dish which has to point in a specific direction, has to point very precisely at the geostationary satellite.  In the case of a Starlink dish, you can basically kind of put it at almost any angle that is reasonably pointed at the sky.”

The questions of interconnection are also a mystery. Say a Starlink user wants to visit a website hosted in Croatia. Does the signal go up to Starlink, between satellites, and down to the nearest base station? Does it go down at a big interconnect point on the backbone serving that region? Does it go up and then come down 20 miles from your house at the place where fiber connects to the local backbone? It may not matter much to ordinary users, but for big services — think Netflix — it could be very important.

And lastly, how much does it cost? SpaceX wants to make this competitive with terrestrial broadband, which is a little hard to believe considering the growth of fiber, but also not that hard to believe because of telecoms dragging their heels getting to rural areas still using DSL. Out there, Starlink might be a godsend, while in big cities it might be superfluous.

Chances are we won’t know for a long time. The 60 satellites up there right now are only the very first wave, and don’t comprise anything more than a test bed for future services. Starlink will have to prove these things work as planned, and then send up several hundred more before it can offer even the most rudimentary service. Of course, that is the plan, and might even be accomplished by the end of the year.

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SpaceX kicks off its space-based internet service tomorrow with 60-satellite Starlink launch

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As wild as it sounds, the race is on to build a functioning space internet — and SpaceX is taking its biggest step yet with the launch of 60 (!) satellites tomorrow that will form the first wave of its Starlink constellation. It’s a hugely important and incredibly complex launch for the company — and should be well worth launching.

A Falcon 9 loaded to the gills with the flat Starlink test satellites (they’re “production design” but not final hardware) is vertical at launchpad 40 in Cape Canaveral. It has completed its static fire test and should have a window for launch tomorrow, weather permitting.

Building satellite constellations hundreds or thousands strong is seen by several major companies and investors as the next major phase of connectivity — though it will take years and billions of dollars to do so.

OneWeb, perhaps SpaceX’s biggest competitor in this area, just secured $1.25 billion in funding after launching the first six satellites in March (of a planned 650). Jeff Bezos has announced that Amazon will join the fray with the proposed 3,236-satellite Project Kuiper. Ubiquitilink has a totally different approach. And plenty of others are taking on smaller segments, like lower-cost or domain-specific networks.

Needless to say it’s an exciting sector, but today’s launch is a particularly interesting one because it is so consequential for SpaceX. If this doesn’t go well, it could set Starlink’s plans back long enough to give competitors an edge.

The satellites stacked inside the Falcon 9 payload fairing. “Tight fit,” pointed out CEO Elon Musk.

SpaceX hasn’t explained exactly how the 60 satellites will be distributed to their respective orbits, but founder and CEO Elon Musk did note on Twitter that there’s “no dispenser.” Of course there must be some kind of dispenser — these things aren’t going to just jump off of their own accord. They’re stuffed in there like kernels on a corncob, and likely each have a little spring that sends them out at a set velocity.

A pair of prototype satellites, Tintin-A and B, have been in orbit since early last year, and have no doubt furnished a great deal of useful information to the Starlink program. But the 60 aboard tomorrow’s launch aren’t quite final hardware. Although Musk noted that they are “production design,” COO Gwynne Shotwell has said that they are still test models.

“This next batch of satellites will really be a demonstration set for us to see the deployment scheme and start putting our network together,” she said at the Satellite 2019 conference in Washington, D.C. — they reportedly lack inter-satellite links but are otherwise functional. I’ve asked SpaceX for more information on this.

It makes sense: If you’re planning to put thousands (perhaps as many as 12,000 eventually) of satellites into orbit, you’ll need to test at scale and with production hardware.

And for those worried about the possibility of overpopulation in orbit — it’s absolutely something to consider, but many of these satellites will be flying at extremely low altitudes; at 550 kilometers up, these tiny satellites will naturally de-orbit in a handful of years. Even OneWeb’s, at 1,100 km, aren’t that high up — geosynchronous satellites are above 35,000 km. That doesn’t mean there’s no risk at all, but it does mean failed or abandoned satellites won’t stick around for long.

Just don’t expect to boot up your Starlink connection any time soon. It would take a minimum of six more launches like this one — a total of 420, a happy coincidence for Musk — to provide “minor” coverage. This would likely only be for testing as well, not commercial service. That would need 12 more launches, and dozens more to bring it to the point where it can compete with terrestrial broadband.

Even if it will take years to pull off, that is the plan. And by that time others will have spun up their operations as well. It’s an exciting time for space and for connectivity.

No launch time has been set as of this writing, so takeoff is just planned for Wednesday the 15th at present. As there’s no need to synchronize the launch with the movement of any particular celestial body, T-0 should be fairly flexible and SpaceX will likely just wait for the best weather and visibility. Delays are always a possibility, though, so don’t be surprised if this is pushed out to later in the week.

As always you’ll be able to watch the launch at the SpaceX website, but I’ll update this post with the live video link as soon as it’s available.

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Israel’s Beresheet spacecraft is lost during historic lunar landing attempt

Posted by | beresheet, Gadgets, Israel, lunar landing, science, Space, SpaceX | No Comments

Israel’s SpaceIL almost made history today as its Beresheet spacecraft came within an ace of landing on the surface of the Moon, but suffered a last-minute failure during descent. Israel missed out on the chance to be the fourth country to make a controlled lunar landing, but getting 99 percent of the way there is still an extraordinary achievement for private spaceflight.

Beresheet (“Genesis”) launched in February as secondary payload aboard a SpaceX Falcon 9 rocket, and after a month and a half spiraling outward, entered lunar orbit a week ago. Today’s final maneuver was an engine burn meant to bring down its relative velocity to the Moon, then brake to a soft landing in the Mare Serenitatis, or Sea of Serenity.

Everything was working fine up until the final moments, as is often the case in space. The craft, having made it perfectly to its intended point of descent, determined that all systems were ready and the landing process would go ahead as planned.

They lost telemetry for a bit, and had to reset the craft to get the main engine back online… and then communication dropped while only a handful of kilometers from the surface. The “selfie” image above was taken from 22 km above the surface, just a few minutes before that. The spacecraft was announced as lost shortly afterwards.

Clearly disappointed but also exhilarated, the team quickly recovered its composure, saying “the achievement of getting to where we got is tremendous and we can be proud,” and of course, “if at first you don’t succeed… try, try again.”

The project began as an attempt to claim the Google Lunar Xprize, announced more than a decade ago, but which proved too difficult for teams to attempt in the time frame specified. Although the challenge and its prize money lapsed, Israel’s SpaceIL team continued its work, bolstered by the support of Israel Aerospace Industries, the state-owned aviation concern there.

It’s worth noting that although Beresheet did enjoy considerable government support in this way, it’s a far cry from any other large-scale government-run mission, and can safely be considered “private” for all intents and purposes. The ~50-person team and $200 million budget are laughably small compared to practically any serious mission, let alone a lunar landing.

I spoke with Xprize’s founder and CEO, Peter Diamandis and Anousheh Ansari, respectively, just before the landing attempt. Both were extremely excited and made it clear that the mission was already considered a huge success.

“What I’m seeing here is an incredible ‘Who’s Who’ from science, education and government who have gathered to watch this miracle take place,” Diamandis said. “We launched this competition now 11 years ago to inspire and educate engineers, and despite the fact that it ran out of time it has achieved 100 percent of its goal. Even if it doesn’t make it onto the ground fully intact it has ignited a level of electricity and excitement that reminds me of the Ansari Xprize 15 years ago.”

He’s not the only one. Ansari, who funded the famous spaceflight Xprize that bore her name, and who has herself visited space as one of the first tourist-astronauts above the International Space Station, felt a similar vibe.

“It’s an amazing moment, bringing so many great memories up,” she told me. “It reminds me of when we were all out in the Mojave waiting for the launch of Spaceship One.”

Ansari emphasized the feeling the landing evoked of moving forward as a people.

“Imagine, over the last 50 years only 500 people out of seven billion have been to space — that number will be thousands soon,” she said. “We believe there’s so much more that can be done in this area of technology, a lot of real business opportunities that benefit civilization but also humanity.”

Congratulations to the SpaceIL team for their achievement, and here’s hoping the next attempt makes it all the way down.

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SpaceX makes history by completing first private crew capsule mission

Posted by | commercial crew, Gadgets, Government, hardware, international space station, ISS, NASA, Space, SpaceX | No Comments

SpaceX’s Crew Dragon capsule has safely splashed down in the Atlantic, making it the first privately built crew-capable spacecraft ever to complete a mission to the International Space Station. It’s one of several firsts SpaceX plans this year, but Boeing is hot on its heels with a crew demonstrator of its own — and of course the real test is doing the same thing with astronauts aboard.

This mission, Demo-1, had SpaceX showing that its Crew Dragon capsule, an evolution of the cargo-bearing Dragon that has made numerous ISS deliveries, was complete and ready to take on its eponymous crew.

It took off early in the morning of March 2 (still March 1 on the West coast), circled the Earth 18 times, and eventually came to a stop (relatively speaking, of course) adjacent to the ISS, after which it approached and docked with the new International Docking Adapter. The 400 pounds of supplies were emptied, but the “anthropomorphic test device” known as Ripley — basically a space crash test dummy — stayed in her seat on board.

(It’s also worth noting that the Falcon 9 first stage that took the capsule to the edge of the atmosphere landed autonomously on a drone ship.)

Five days later — very early this morning — the craft disengaged from the ISS and began the process of deorbiting. It landed on schedule at about 8:45 in the morning Eastern time.

It’s a huge validation of NASA’s Commercial Crew Program, and of course a triumph for SpaceX, which not only made and launched a functioning crew spacecraft, but did so before its rival Boeing. That said, it isn’t winner take all — the two spacecraft could very well exist in healthy competition as crewed missions to space become more and more common.

Expect to see a report on the mission soon after SpaceX and NASA have had time to debrief and examine the craft (and Ripley).

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SpaceX’s Crew Dragon makes its first orbital launch tonight

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After years of development and delays, SpaceX’s Crew Dragon is ready to launch into orbit. It’s the first commercially built and operated crewed spacecraft ever to do so, and represents in many ways the public-private partnership that could define the future of spaceflight.

Launch is set for just before midnight Pacific time — 2:49 Eastern time in Cape Canaveral, from where the Falcon 9 carrying the Crew Dragon capsule will take off. It’s using Launchpad 39A at Kennedy Space Center, which previously hosted Apollo missions and more recently SpaceX’s momentous Falcon Heavy launch. Feel free to relive that moment with us, while you’re here:

The capsule has been the work of many years and billions of dollars: an adaptation of the company’s Dragon capsule, but with much of its cargo space converted to a spacious crew compartment. It can seat seven if necessary, but given the actual needs of the International Space Station, it is more likely to carry two or three people and a load of supplies.

Of course it had to meet extremely stringent safety requirements, with an emergency escape system, redundant thrusters and parachutes, newly designed spacesuits, more intuitive and modern control methods and so on.

Crew Dragon interior, with “Ripley”

It’s a huge technological jump over the Russian Soyuz capsule that has been the only method to get humans to space for the last eight years, since the Shuttle program was grounded for good. But one thing Dragon doesn’t have is the Soyuz’s exemplary flight record. The latter may look like an aircraft cockpit shrunk down to induce claustrophobia, but it has proven itself over and over for decades. The shock produced by a recent aborted launch and the quickness with which the Soyuz resumed service are testament to the confidence it has engendered in its users.

But for a number of reasons the U.S. can’t stay beholden to Russia for access to space, and at any rate the commercial spaceflight companies were going to send people up there anyway. So NASA dedicated a major portion of its budget to funding a new crew capsule, pitting SpaceX and Boeing against one another.

SpaceX has had the best of Boeing for the most part, progressing through numerous tests and milestones, not exactly quickly, but with fewer delays than its competitor. Test flights originally scheduled for 2016 are only just now beginning to take place. Boeing’s Starliner doesn’t have a launch date yet, but it’s expected to be this summer.

Tonight’s test (“Demo-1”) is the first time the Crew Dragon will fly to space; suborbital flights and landing tests have already taken place, but this is a dry run of the real thing. Well, not completely dry: the capsule is carrying 400 pounds of supplies to the station and will return with some science experiments on board.

After launch, it should take about 11 minutes for the capsule to detach from the first and second stages of the Falcon 9 rocket. It docks about 27 hours later, early Sunday morning, and the crew will be able to get at the goodies just in time for brunch, if for some reason they’re operating on East Coast time.

SpaceX will be live streaming the launch as usual starting shortly before takeoff; you can watch it right here:

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SpaceX’s Starship goes sci-fi shiny with stainless steel skin

Posted by | BFR, Elon Musk, Gadgets, science, Space, SpaceX, Starship, TC | No Comments

SpaceX’s futuristic Starship interplanetary craft may embody the golden age of sci-fi in more ways than one: in addition to (theoretically) taking passengers from planet to planet, it may sport a shiny stainless steel skin that makes it look like the pulp covers of old.

Founder and CEO Elon Musk teased the possibility in a picture posted to Twitter, captioned simply “Stainless Steel Starship.” To be clear, this isn’t a full-on spacecraft, just part of a test vehicle that the company plans to use during the short “hopper” flights in 2019 to evaluate various systems.

As with most Musk tweets, this kicked off a storm of speculation and argument in the Twitterverse.

The choice surprised many because for years, modern spaceflight has been dependent on advanced composite materials like carbon fiber, which combine desirable physical properties with low weight. When metal has been required, aluminum or titanium are much more common. While some launch components, like the upper stage of the Atlas 5 rocket, have liberally used steel, it’s definitely not an obvious choice for a craft like the Starship, which will have to deal with both deep space and repeated reentry.

As Musk pointed out in subsequent comments, however, stainless steel has some advantages versus other materials when at extremely hot or cold temperatures.

Usable strength/weight of full hard stainless at cryo is slightly better than carbon fiber, room temp is worse, high temp is vastly better

— Elon Musk (@elonmusk) December 24, 2018

This is a special full-hardness steel alloy mentioned as being among the 300 series of high-strength, heat-resistant alloys — not the plentiful, pliable stuff we all have in our kitchens and buildings. Musk also mentioned another “superalloy” called SX500 that SpaceX’s metallurgists have developed for use in the Raptor engines that will power the vehicle.

So why stainless? It’s likely all about reentry.

Many craft and reusable stages that have to face the heat of entering the atmosphere at high speed use “ablative” heat shielding that disintegrates or breaks away in a controlled fashion, carrying heat away from the vehicle.

It’s unlikely this is a possibility for Starship, however, as replacing and repairing this material would necessitate downtime and crews wherever and whenever it lands, and the craft is meant to be (eventually) a quick-turnaround ship with maximum reusability. Heat shielding that reflects and survives is a better bet for that — but an enormous engineering problem.

Scott Manley put together a nice video illustrating some of these ideas and speculations in detail:

Musk said before of the Starship (then still called BFR) that “almost the entire time it is reentering, it’s just trying to brake, while distributing that force over the most area possible.” Reentry will probably look more like a Space Shuttle-esque glide than a Falcon 9 first stage’s ballistic descent and engine braking.

The switch to stainless steel has the pleasant side effect of making the craft look really cool — more in line with sci-fi books and comics than their readers perhaps ever thought to hope. Paint jobs would burn right off, Musk said:

Skin will get too hot for paint. Stainless mirror finish. Maximum relfectivity.

— Elon Musk (@elonmusk) December 24, 2018

You can’t expect it to stay shiny for long, though; it may be stainless, but like a pan you left on the stove, stainless steel can still scorch and the bottom of the Starship will likely look pretty rough after a while. It’s all right — spacecraft developing a patina is a charming evolution.

Details are still few, and for all we know SpaceX could redesign the craft again based on how tests go. Next year will see the earliest hopper flights for Starship hardware and possibly the Super Heavy lower stage that will lift its great shiny bulk out of the lower atmosphere.

The technical documentation promised by Musk should arrive in March or April, but whether it will pertain solely to the test vehicle or give a glimpse at the craft SpaceX intends to send around the moon is anyone’s guess. At any rate you should expect more information to be spontaneously revealed before then at Musk’s discretion — or lack thereof.

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SpaceX’s Starlink aims to put over a thousand of its communications satellites in super-low orbit

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SpaceX’s planned communication satellite constellation, known as Starlink, will now be targeting a much lower orbit than originally planned, at least for over a thousand of the satellites, the company revealed in an FCC filing. The move should help mitigate orbital debris and provide better signal for the company’s terrestrial users as well.

Starlink plans to put 1,584 satellites — about a third of the 4,409 the company aims to launch — in an orbit just 550 kilometers about the surface of the Earth. For comparison, many communications satellites are in orbits more than twice as high, and geosynchronous orbits are more than 20 times farther out (around 36,000 miles).

At that distance orbits decay quickly, falling into the atmosphere and burning up after a handful of years. But SpaceX isn’t daunted; in fact, it writes in its application, lower orbits offer “several attractive features both during nominal operation and in the unlikely event something goes wrong.”

In the first place, orbital debris problems are naturally mitigated by the fact that anything in that low orbit will fall to Earth quickly instead of cluttering up the orbit. Second, it should shorten the amount of time it takes to send and receive a signal from the satellites — ping time could be as low as 15 milliseconds, the company estimated. And 500 fewer kilometers means there will be less spreading for beam-based communications, as well.

The satellites will have to do more work to stay at their optimal altitude, as atmospheric drag will be higher, and each one will be able to see and serve less of the planet. But with thousands working together, that should be manageable.

The decision was informed by experimental data from the “Tintin” test satellites the company launched earlier this year. “SpaceX has learned to mitigate the disadvantages of operating at a lower altitude and still reap the well-known and significant benefits discussed above,” it wrote.

This change could lead to competitive advantages when satellite communications are more widely used, but it will also likely lead to a more intensive upkeep operation as Starlink birds keep dropping out of the air. Fortunately a third benefit of the lower orbit is that it’s easier to reach, though probably not so much easier that the company breaks even.

Starlink is aiming for the first real launches of its systems early next year, though that timeline may be a little too ambitious. But SpaceX can do ambitious.

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SpaceX lands Falcon 9 booster on Just Read The Instructions drone ship

Posted by | booster, falcon, Falcon 9, Gadgets, science, Space, spacecraft, spaceflight, SpaceX, transport | No Comments

SpaceX confirmed on Twitter this morning that it recovered the booster from the latest Falcon 9 launch. Shortly after launching from Vandenberg Air Force Base in Southern California at 7:39AM ET this morning, the booster stage landed on the Just Read The Instructions drone ship. The company will now try to catch the rocket’s fairing with a giant net attached to the ship Mr. Stevens.

Despite challenging weather conditions, Falcon 9 first stage booster landed on Just Read the Instructions.

— SpaceX (@SpaceX) July 25, 2018

SpaceX has become more adept at landing its booster rockets but it’s still a spectacle every time it happens. This landing is extra special as the winds were gusting around the time of the launch.

The rocket company has so far been less successful with catching the payload shrouds. SpaceX’s high-speed recovery boat Mr. Steven took to the seas this time around with a larger net in the hopes of recovering the fairings. Reusing as much as possible is critical to SpaceX’s mission to lower the cost of space flight.

Today’s launch was SpaceX’s seventh mission for the company’s client Iridium who contracted with SpaceX to launch 75 satellites into orbit. According to SpaceX, today’s payload of Iridium satellites so far deployed without an issue. SpaceX is contracted for one more launch with Iridium.

This was SpaceX’s 14th launch of 2018.

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Watch SpaceX launch NASA’s new planet-hunting satellite here

Posted by | Gadgets, hardware, NASA, science, Space, SpaceX, TESS | No Comments

It’s almost time for SpaceX to launch NASA’s TESS, a space telescope that will search for exoplants across nearly the entire night sky. The launch has been delayed more than once already: originally scheduled for March 20, it slipped to April 16 (Monday), then some minor issues pushed it to today — at 3:51 PM Pacific time, to be precise. You can watch the launch live below.

TESS, which stands for Transiting Exoplanet Survey Satellite, is basically a giant wide-angle camera (four of them, actually) that will snap pictures of the night sky from a wide, eccentric and never before tried orbit.

The technique it will use is fundamentally the same as that employed by NASA’s long-running and highly successful Kepler mission. When distant plants pass between us and their star, it causes a momentary decrease in that star’s brightness. TESS will monitor thousands of stars simultaneously for such “transits,” watching a single section of sky for a month straight before moving on to another.

By two years, it will have imaged 85 percent of the sky — hundreds of times the area Kepler observed, and on completely different stars: brighter ones that should yield more data.

TESS, which is about the size of a small car, will launch on top of a SpaceX Falcon 9 rocket. SpaceX will attempt to recover the first stage of the rocket by having it land on a drone ship, and the nose cone will, hopefully, get a gentle parachute-assisted splashdown in the Atlantic, where it too can be retrieved.

The feed below should go live 15 minutes before launch, or at about 3:35.

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