SpaceX Successfully Lands Falcon 9 Rocket On Solid Ground For the Second Time (theverge.com)

SpaceX successfully landed another Falcon 9 rocket after launching the vehicle into space on Sunday evening from Florida. The Verge reports: Shortly after takeoff, the vehicle touched down at SpaceX's Landing Complex 1 -- a ground-based landing site that the company leases at the Cape. It marks the second time SpaceX has pulled off this type of ground landing, and the fifth time SpaceX has recovered one of its rockets post-launch. The feat was accomplished a few minutes before the rocket's second stage successfully put the company's Dragon spacecraft into orbit, where it will rendezvous with the International Space Station later this week. It's also the first time this year SpaceX has attempted to land one of its rockets on land. For the past six launches, each rocket has tried landing on an autonomous drone ship floating in the ocean. That's because drone ship landings require a lot less fuel to execute than ground landings.

Comments

Beautiful by the numbers launch / deploy / landing

[Mysticalfruit]

What that said the launch was by the numbers and was awesome. I've got friends in FL who heard the sonic boom of the first stage reentering.

Since they were only boosting Dragon to LEO they didn't have to deploy the drone ship. I watched it online last night. I did notice the feed started with only a few minutes before launch which saddened me because I like to listen in on the launch coordinator loop while they're going through all the preflight checks.

Hopefully SpaceX will expose the audio feed so those of us who are nerds about this can listen in for the whole thing.

Still waiting, Jetsons.

[Narcocide]

Ok great now where is my flying commuter-car that folds out of a briefcase? Get on it now, please.

Re:Still waiting, Jetsons.

[Anonymous Coward]

I would take a non-flying commuter car that folds out of a briefcase!

Re:Still waiting, Jetsons.

[magarity]

There are several briefcase commuter vehicles on the market

Re: Still waiting, Jetsons.

[Anonymous Coward]

That's an electric bicycle

Re:Still waiting, Jetsons.

[AJWM]

James Bond had one, Little Nelly, in You Only Live Twice, although come to think of it that was four briefcases. Well, okay, suitcases.

Some assembly required.

Number of landings

[meza]

So, according to the summary it's the second time they land on ground, but the first time they attempt to land on ground ... Meaning once they tried to land on the drone ship but missed and landed on land instead?

Re:Number of landings

[kwerle]

the first time *this year* SpaceX has attempted to land one of its rockets on land

Re:Number of landings

[Anonymous Coward]

This year being the critical point. 1st attempt this year :)

Re:Number of landings

[Mr D from 63]

So, according to the summary it's the second time they land on ground, but the first time they attempt to land on ground ... Meaning once they tried to land on the drone ship but missed and landed on land instead?

But this one was on 'solid ground'. Pay attention.

Re:Number of landings

[Mr D from 63]

Next try will be on 'dry land'.

Re: Number of landings

[Anonymous Coward]

Because that's a essential point?

Re:Number of landings

[Anonymous Coward]

Everyone said Musk was daft to land a rocket on a swamp, but he landed it all the same, just to show them. It sank into the swamp. So he landed a second one. That sank into the swamp. So he landed a third. That burned down, fell over, then sank into the swamp. But the fourth one stayed up. And that's what you're going to get, Lad, the strongest rocket in all of England.

Re: Number of landings

[Anonymous Coward]

Yes?

Re: Number of landings

[Anonymous Coward]

This is the second attempt to land back at Canaveral, with both attempts successful. The first was the launch of 11 satellites for Orbcomm late last year.

That Pokemon GO reference at the end.

[Pezbian]

I'd throw any number of Pokeballs at a CP2024 Dragon Capsule to catch it.

Re:Beautiful by the numbers launch / deploy / land

[TheSync]

"I've got friends in FL who heard the sonic boom of the first stage reentering."

I watched some Periscope recordings from people watching the landing, and they all seemed to be shocked by the loudness of the sonic boom. Some thought the 1st stage booster exploded after landing (because it takes a while for the sound to reach them).

SpaceX claims "this is no worse than the sonic boom from the shuttle landing", but I don't know, I've heard the sonic boom from the shuttle landing at Edwards and it was like someone hitting a drum, not like an explosion.

NASA was lucky to land one shuttle per month, whereas SpaceX has dreams of launching/landing once per week.

Also the people near the Space Coast or Vandenberg might be able to deal with the sonic booms (as space is pretty much their whole industry), but if SpaceX moves launches/landings to Brownsville, Texas, I can imagine they will upset a lot of people in Harlingen, McAllen, and Corpus Christi not used to rocket launches or supersonic aircraft (not to mention our friends across the border in Reynosa).

Space Adapters

[burhop]

One of the interesting things in this trip are a couple of Space adapters that will let Boeing's CST-100 Starliner, SpaceX's Crew Dragon
spacecraft, and anyone else that comes along to dock to the station.

http://www.theverge.com/2016/7...

No word yet on if Apple will follow this standard or come up with their own.

Re:Space Adapters

[D.McG.]

One of the interesting things in this trip are a couple of Space adapters

There is only a single IDA in the CRS-9 dragon trunk this trip.

IDA-3 (to replace the lost IDA-1 from CRS-7) is targeted to launch on CRS-12 in May 2017.

Re:Space Adapters

[burhop]

Ah... you are right. Like you pointed out, the second goes up later.

Re:Space Adapters

[WindBourne]

The other 2 crafts that might make use the LIDS would be the Orion capsule as well as SNC's Dream Chaser.

"Propellant" is the preferred term

[Anonymous Coward]

Nit pick: "...drone ship landings require a lot less *propellant* to execute..."

These rockets consume fuel and oxidizer, so I believe it's preferred to say "propellant" instead of "fuel".

Re:"Propellant" is the preferred term

[Anonymous Coward]

Hey, it's a valid point. Sometimes that kind of pedantry is called for.

Anonymous Coward: Not the pedant we need, the pedant we deserve.

And they don't even call it Autopilot!

[Ecuador]

It lands by itself and they don't even call it Autopilot! In this case nobody would object, but they don't market it as such... Oh, well... ;)

Drone ship landing not because of fuel

[linuxgurugamer]

Actually, the reason for the Drone ship is that some cargoes are launched higher and faster than others, and the booster stage just can't get back to land based on the launch profile

Re:Drone ship landing not because of fuel

[nitehawk214]

As in, the booster does not have enough fuel to cancel out its momentum and position itself over the launch point.

Re:Drone ship landing not because of fuel

[cbhacking]

Well, in theory it *could* if it had the fuel, and I bet that for a really light GTO payload they could manage to save enough fuel for the boostback burn, but in practice satellites intended for GSO aren't that light. It would be a longer boostback burn (than for LEO) anyhow, because the first stage is usually going faster at separation when it's targeting GTO, but for a really light payload the second stage wouldn't need to burn for as long either so maybe the first stage could separate a little earlier.

No matter what the target orbit, the first stage will always be well down-range, and have a lot of velocity in that down-range direction, at separation. For ground landings, it needs to reverse that velocity to come back to the launch site, then do another burn to slow down enough to not burn up in the atmosphere, and then the landing burn. For GTO launches, it usually skips the first burn (boostback) and just continues along that down-range trajectory, doing just the re-entry and then landing burns. This obviously needs less fuel, but also means that the rocket is hundreds of miles downrange by the time it lands.

It's not theoretically impossible to do a full boostback burn after a GTO launch, though... just impractical given how much fuel the first stage uses on the ascent of a GTO launch.

Re:Drone ship landing not because of fuel

[slashdotwannabe]

This is a perfect opportunity for Tesla to put a SuperCharger station along the path for a quick re-fuel on the way home! Wait...

Re:Beautiful by the numbers launch / deploy / land

[Mysticalfruit]

So when they start landing Falcon Heavy boosters are the two side boosters going to be landing there and the 3rd out at the drone ship?

Re:Beautiful by the numbers launch / deploy / land

[Vulch]

That's the plan. It may be possible for some launches to have all three come back to dry land if the payload is at the low end of capabilities.

drone ship landings require a lot less fuel?

[Holi]

Can anyone explain why landing on a ship uses a lot less fuel then on land. I would think since you have to be far more accurate to land on a ship it would require more fuel.

Re:drone ship landings require a lot less fuel?

[Anonymous Coward]

my guess would be the distance involved?

Re:drone ship landings require a lot less fuel?

[hackertourist]

The rocket launches due East from the Cape. The droneship is in a straight line underneath the flightpath, so the stage flies more or less a parabolic arc to the ship.
To fly back to the Cape, the stage has to brake and bring its velocity to 0, then accelerate to the West to get back to land.
Flying to the drone ship skips the 'brake' part, which saves a lot of fuel.

Re:drone ship landings require a lot less fuel?

[magarity]

Have you never watched video of a launch from Florida? The rockets arc out over the ocean. Thus, to get back to Florida requires some amount of turning back versus continuing the arc to land out in the ocean.

Re:drone ship landings require a lot less fuel?

[Anonymous Coward]

I wondered too.....
possible guesses: location/distance/route to land requires more fuel than where barge located
far out guess: ocean (or barge-ocean interface movement) absorbes some of landing force allowing higher landing velocity
or: landing on land is closer to people to regulations or saftey cause more fuel to be used
or: false or inaccurate information

Re:drone ship landings require a lot less fuel?

[Rei]

Because the land landings mean turning around and reversing your momentum to get back to where you started.

Remember, going to orbit isn't so much about going up as it is about going across really, really fast. "Going up" is just to get high enough that you don't suffer from aero drag, it's a significant minority of the total energy requirements.

Re:drone ship landings require a lot less fuel?

[Binestar]

Can anyone explain why landing on a ship uses a lot less fuel then on land. I would think since you have to be far more accurate to land on a ship it would require more fuel.

This one is easy. The stage has to travel less of a distance to land on a ship in the ocean vs turning around and landing on the ground. And you're also incorrect about accuracy. You have to be identically accurate to land on a 300x170 foot barge and on a 300x170 foot "X" on land.

Re:drone ship landings require a lot less fuel?

[Rei]

Although, on the other side of the equation it's not as bad as it could be for several reasons:

1) The first stage does most of the "up", the second stage is almost entirely about the "across" portion. The first stage also does part of the "across", but its main purpose is to get the second stage out of the atmosphere to where it can operate efficiently.

2) The second stage comes back vastly ligher than it left.

3) Aero drag helps get rid of part of the forward velocity.

That said, it's still very difficult to get back, because getting to orbit is so demanding to begin with. You can't just reserve a quarter of your fuel for the return and still plan to get a useful payload to orbit. You have to return running on the dregs of the tanks.

Re:drone ship landings require a lot less fuel?

[nitehawk214]

Here is the launch profile. http://i.imgur.com/D9BdO86.png

Launches to GTO need to be going a lot faster (7.7 km/s for ISS, vs 9.88 km/s for GTO). The Falcon 9 uses up enough fuel that it cannot execute the "boostback" burn listed in the image.

Instead it continues on in a parabolic arc until it hits the atmosphere to slow down, firing the rocket at the last minute to stop over the drone ship.

https://upload.wikimedia.org/w...

Re:drone ship landings require a lot less fuel?

[foxalopex]

Actually this isn't too hard to figure out why. Keep in mind two things, first the rockets are launched over ocean to make sure that if they do crash, they hopefully just land in the empty sea where they won't bother anyone. Second think of it like throwing a ball. To get it into high orbit you need a lot of forward momentum to keep it up there. You can't just throw it straight up because then it'll just fall back to earth or escape earth's gravity into deep space. It needs to be an arc. When shooting it into high orbit, the rocket's already gone so far offshore that it would take far too much fuel to return back to land so it's easier to let it fall in an arc onto a drone ship at sea. When going into low orbit there doesn't need to be so much forward momentum so it isn't as far offshore so it can return back to land. Another way to picture this, if the rocket simply cut out when it finished boosting the payload where would it end up without any assistance.

Re:drone ship landings require a lot less fuel?

[jittles]

You have to be identically accurate to land on a 300x170 foot barge and on a 300x170 foot "X" on land.

I don't know... I think it would be kind of cute if they just landed it anywhere and the rocket ended up inside of my house.

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

To return to landing site it goes UP, back, and down. Orbital mechanics.

East takes you out, out takes you west, west takes you in, in takes you east, port and starboard bring you home.

Re:drone ship landings require a lot less fuel?

[D.McG.]

Landing on the drone ship downrange, nearly inline with the ballistic trajectory of the first stage, only requires two burns. a re-entry burn and a landing burn. There isn't enough propellant when downrange that far (for Geostationary Transfer Orbit missions) to do a third boost-back burn to get back to the Florida coast. By not performing a boost-back burn, they use less propellant.

The rocket also don't have enough propellant (or throttle range) to hover for corrections, so accuracy does not come from expending more fuel. I mentioned "nearly inline" earlier. If the engines fail to ignite for the re-entry burn, the rocket will ballistically fall short into the ocean for safety. If the engines ignite, then the rocket is steered onto the drone ship by the grid fins and engine gimbaling.

Missions to Low Earth Orbit do not require as much propellant, so there's enough remaining after the primary mission to perform a boost-back burn to the Florida coast. GTO missions fire the first stage for 160 seconds, while the CRS-9 mission only fired the first stage for 140 seconds. that's 20 seconds of extra propellant for 9 engines, or 60 seconds of propellant for 3 engines.

Re:drone ship landings require a lot less fuel?

[cbhacking]

Yep. The video doesn't make it clear, because the cameras are all either tracking the rocket or are mounted *on* the rocket, but the first stage is going really fast at separation, and a lot of that velocity is lateral. Going to *space* only requires going up a relatively short distance, but going to *orbit* requires going extremely fast around the planet. After the first few seconds post-liftoff, the rocket is angled mostly downrange, not just up. To come back to the launch site, the rocket not only needs to kill all that down-range velocity, it needs to boost *back* to the launch site.

The rocket does actually need to do a braking burn when landing on a downrange barge anyhow, but the purpose is different. Rather than being focused on reversing the rocket's forward trajectory, it's focused on slowing the rocket down so it can re-enter the atmosphere safely. By the time of separation, the stages are quite high - well out of the thick part of the atmosphere - and sheer momentum will take them quite a bit higher. Eventually gravity takes over, though, and between gravity pulling the rocket downward and that downrange momentum still making it go forward so fast, the rocket wouldn't survive re-entry if it didn't use its motors to slow down. This re-entry braking burn is done both for land and sea landings.

Re:drone ship landings require a lot less fuel?

[MachineShedFred]

cancelling 100% of your eastbound velocity and thrusting back to return to where you came from takes far more fuel than cancelling 100% of your eastbound velocity to land on something that is farther east.

Re:drone ship landings require a lot less fuel?

[MachineShedFred]

Yay, slashdot fails at less-than and greater-than symbols. Should have read "far more fuel than cancelling [less than] 100% of your eastbound velocity to land on something that is further east"

Re:drone ship landings require a lot less fuel?

[sconeu]

You mean the charred ruins of what USED to be your house, along with the smashed up houses of your neighbors (since there wouldn't be a flat area for it to land and stay standing).

Re:drone ship landings require a lot less fuel?

[Anonymous Coward]

That's call the html (or markup) disease. Boy, how do I hate the so called "angle brackets", usurping their natural mathematical meaning.

Re: drone ship landings require a lot less fuel?

[AJWM]

Yeah, many of us here have read Niven's Integral Trees too. The thing is, the Falcon 9 first stage is nowhere near orbit (in velocity terms), so "I think you'll find that turns out not to be the case."

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

Here's an illustration of the boost-back to RTLS trajectory. You can see that it very definitely goes up. And to prove from observation, you can actually see where the two trajectories separate in photos from yesterday's launch. It's a rather dim curl up, and another continuing East, in Jason Ruck's photo and John Kraus's photo.

At the speed of stage separation, they rocket isn't going fast enough to stay in orbit, but it is definitely in the regime where orbital mechanics has a macroscopic effect. If you think about it, this is going to be the case at some reasonable fraction of orbital velocity.

Re: drone ship landings require a lot less fuel?

[budgenator]

Orbit is just a freefall where the falling object doesn't get closer to the center of gravity.

Re:drone ship landings require a lot less fuel?

[Anonymous Coward]

Yeah! SO AWESOME!

Re: drone ship landings require a lot less fuel?

[cjameshuff]

It goes up because it's already going up at stage separation. Gravity will take care of reversing the vertical component of its motion, so there's no point in burning fuel to halt the upward motion: the boostback burn only has to reverse the horizontal motion. If allowed to continue on a parabolic arc to an ASDS landing, its peak altitude would be similar, it'd just be reached much further downrange.

"Out takes you west", etc. only works for objects in orbit, relative to other objects in orbit. Objects in lower orbit move faster and travel east relative to objects in higher orbits. Earth's surface isn't moving at orbital velocity and will continue to trail behind to the west until you get up past geosynchronous orbit. The RTLS trajectory is more like a ball bouncing off a vertical wall than anything to do with orbital dynamics.

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

It seems to be a common misconception that orbital mechanics somehow knows when you are in orbit and does not work otherwise. But that is as silly as saying that relativity only works near light speed. These things always work regardless of speed, it's just that their effects are macroscopic at greater speeds.

Re:drone ship landings require a lot less fuel?

[cjameshuff]

Even worse: canceling out your eastbound velocity, burning westward, and then canceling out your now-westward velocity so you can land. You can manage some of that with aerodynamics rather than rocket power, fortunately.

The propellant requirements of returning to land are considerably higher, roughly doubling the payload penalty. However, it means you don't have to run a barge and its support boat for a couple weeks and can immediately get started on preparing the stage for reuse, and the propellant is dirt cheap, so it's very worth doing when they can manage it.

Re: drone ship landings require a lot less fuel?

[cjameshuff]

It's not that orbital mechanics knows if you're in orbit or not, it's that it simply isn't involved if you aren't. The rules of thumb you quoted work between objects in reasonably circular orbits because objects in lower circular orbits travel faster than those in higher orbits. The launch/landing site is not in any kind of orbit and is moving at only a few percent of what orbital velocity at sea level would be, and the first stage is in an extremely eccentric orbit that intersects the ground just a hundred km or so below apogee and which can accurately be analyzed as a parabolic trajectory over flat ground.

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

I put the question to the reddit spacex group, some of the folks there are heavily into dynamic simulation. If you are right, all of the illustrations are wrong, including one from SpaceX.

Re: drone ship landings require a lot less fuel?

[AJWM]

Oh really?

Explain highly elliptical (eg cometary) orbits then.

Orbit is a freefall where the horizontal* component of speed at apoapsis is sufficient to avoid hitting the source of gravity at or near periapsis. The first stage booster doesn't come anywhere near fast enough at its apogee.

*horizontal: i.e, perpendicular to a line drawn between the object and the center of gravity of the system.

Re: drone ship landings require a lot less fuel?

[AJWM]

Oh, well, if reddit users say it is so, then it must be true. [eye roll]

Argument from authority? Really?

The "east takes you up" phrasing is just a handy mnemonic for epicycles, which are a useful (in some cases) simplification of elliptical orbits (which is what a circular orbit becomes if perturbed). Fairly useless for accurate orbital modelling, or for (significantly) suborbital trajectories. (Both of which apply if you're trying to land a booster on a barge or parking lot.)

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

Well, Alastair, you should probably not get snotty and ad-hominem, unless you want me to comment on how a one-time sci-fi author and the Unix guy at Dish doesn't really have more authority than the random person one might find in the SpaceX group on Reddit.

It happens there are a few people over there who are rocketry professionals, have the math, and have followed SpaceX long enough. So, sure, their opinion can indeed be trusted.

So far, we have a suggestion from one of the lesser folks there that raising the apogee takes advantage of the Earth's rotation. We'll see if we get the attention of the right people.

Re: drone ship landings require a lot less fuel?

[cjameshuff]

If you truly found someone at Reddit who told you that the stage went west by thrusting up, you found someone who doesn't have a damn clue what they're talking about, and you should find someone else. Ignoring the issues of inadequate propellant and far more severe reentry conditions, the stage would have to go far higher than a couple hundred of km, and fly for far longer to allow the launch site to catch up and pass beneath it, and then it'd end up far to the south of the actual launch and landing sites due to the non-equatorial launch site. Earth only rotates about 2.5 degrees between launch and landing, the stage has the same initial velocity as Cape Canaveral and only travels a few hundred km in any direction, none of the factors that make orbital mechanics counterintuitive are significant here. None of the people who are doing simulations (you're talking to one of them here) will tell you otherwise.

And no, those diagrams are mostly correct, and nothing I've said conflicts with them...they show a horizontal boostback burn, contrary to the rule of thumb you quoted. Your mis-application of an approximate rule only appropriate for objects in the nearly-circular coplanar orbits of Niven's smoke ring (or in a very limited sense unrelated to landing, for maneuvers around geostationary orbit), on the other hand, does. It's not even internally consistent, by that reasoning the stage should fly off to the east as it descends, and the final burn should be done horizontally, like a capsule docking with the space station from above or below. SpaceX certainly needs to take factors like the rotating reference frame into account in order to hit their landing spots, but for just understanding the maneuvers it is entirely appropriate to treat them as basically parabolic trajectories over flat ground.

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

I don't need to stand by the rotation theory. However, the 2.5 degrees that the Earth rotates are about equivalent to the downrange distance.

The first stage is going about 1/5 of the target LEO orbital velocity at separation. While you might well model the trajectory as a parabola over flat ground, given the lack of fuel I would expect that SpaceX puts a lot more care into their trajectory. So far I've failed to attract the attention of the person responsible for Flight Club, the most trusted modeling of SpaceX flights, but I'll message him directly.

Re: drone ship landings require a lot less fuel?

[cjameshuff]

2.5 degrees is about 245 km. Without the boostback, the stage ends up coming down about twice that distance to the east of the launch site despite that motion. But that's missing the point, particularly for RTLS: the directions considered horizontal and vertical are basically identical at launch and landing, and adding to vertical velocity after staging will only send the stage further downrange (unless you posit spending utterly unrealistic amounts of delta-v on the maneuver). RTLS is not an orbital maneuver, and the reasons for those rules of thumb you quoted do not apply. And yes, of course SpaceX accounts for Earth's rotation and so on, they need to actually hit a precise landing target. However, they are irrelevant to understanding the basic maneuvers, and simply do not require the maneuvers you describe.

Another factor is that if things were done as you say, the RTLS would take far, far longer than the ASDS landings, because the stage would have to be thrown on a high enough trajectory that the landing site could come into position under it, which would take much more of a rotation. The fact that CRS-9 did the entry burn just 4 minutes after the boostback burn should be another hint that something's wrong with your analysis.

Since you apparently trust Flight Club, just look at their CRS-9 model: https://flightclub.io/results/...
The boostback burn happens from 162 to 211 s. For the first 7 seconds of that, it is completing a maneuver to a pitch angle of -2 degrees, where it remains for the remainder of the burn.

Re: drone ship landings require a lot less fuel?

[AJWM]

You left out astronaut candidate, past president (among other offices) of two L5 chapters, participant in the Citizen's Advisory Council on National Space Policy, and author of a few papers appearing in AIAA publications, among other things.

Still, not bad web surfing for a guy who once helped animate the Genesis simulation sequence in "Wrath of Kahn". ;-)

(Oh, and more than "one-time" unless you mean that in a generic "once and future" sense. Just taking Analog, they've published me at least five times, but it has been a while. I've been focusing on a novel series.)

Cheers,

Re: drone ship landings require a lot less fuel?

[Bruce Perens]

I have the front panel of the VAX 11/780 used to render that scene hanging on my wall, but I got to Pixar after that project. This year and last I've contributed some designs that will fly on a FEMA satellite, and a long time ago did a little work to support the Biosciences mission on the shuttle.

Re:Beautiful by the numbers launch / deploy / land

[ventsyv]

For 2016 they are hoping to do 16 launches and that's considered overly optimistic, SpaceX has been doing around 10 launches per year. To get to 1 launch per week (52 per year) is a huge step forward and will not come for years. Even if they do get to 1 launch per week, with 3 launch sites that's still 17 launches per site per year. Of those only LEO missions can return to the launch location, launches to GEO have to land downrage on a drone ship. All in all, the good people of Texas have nothing to worry about.

Re:Beautiful by the numbers launch / deploy / land

[Mysticalfruit]

It'll be cool to watch... I'm sure they'll be some RUD's until they get the whole thing perfected.

Re:Beautiful by the numbers launch / deploy / land

[ensignyu]

SpaceX started streaming a live "technical webcast" feed for the last several launches; here's the one for last night's launch: https://www.youtube.com/watch?...

In the past I think it's been linked from the webcast page, but you can also find it by searching Youtube.

Less fuel landing on drone barge?

[Anonymous Coward]

"[...]That's because drone ship landings require a lot less fuel to execute than ground landings."

Source of this factoid? Not mentioned anywhere in the articles and at face value does not seem valid.

My understanding was they couldn't get approval for land-based landings because of the inherent risk of the braking maneuver failing and the lithobraking maneuver succeeding with expected consequences.

Re:Less fuel landing on drone barge?

[erice]

The barge is placed down range so that the booster does not have to reverse course to return near the launch site. It just continues on a ballistic path, only firing up the engines to allow a soft landing.

http://www.theverge.com/2016/4...

Re:Less fuel landing on drone barge?

[Anonymous Coward]

Now that makes more sense - they're repositioning the landing site versus adding the extra fuel to change their angle of descent. Thanks for the link :D

Re:Less fuel landing on drone barge?

[mschuyler]

Well, they SAID so, for one thing, if you listened to the live feed. They also explained that getting a heavy satellite into high earth orbit costs a lot more fuel than getting a supply ship into low earth orbit, so they have more fuel left over from an ISS supply than a satellite launch. This allows them to spend the extra fuel to get it back to land. One a satellite launch they simply don't have enough fuel so they are forced to land on the barge.

Re:Beautiful by the numbers launch / deploy / land

[x_t0ken_407]

My FB lit up with people talking about the sonic boom, wondering wtf it was, lol! I just figured it was something I hadn't read about yet, and you've solved that for me, haha.

Re:Beautiful by the numbers launch / deploy / land

[whopis]

The shuttle sonic booms could be very loud at times. They would often set off car alarms in the area.

Ground Versus Ship Landings

[FrankDrebin]

The "lot less fuel" statement in the summary may be technically true, but the main reason for the drone ship versus ground landings are the launch parameters for the payload. From Florida, Dragon to the ISS is a ~50 degree inclination LEO shooting NE, whereas communication satellites are geosynchronous shooting ESE. The former launch separates stages quite close to land, whereas the latter separation is quite far out over the Atlantic.

Re: Ground Versus Ship Landings

[Anonymous Coward]

They've shown they can land on land and land at sea. When are they gonna try to sea on sea and sea at land?

Re:I didn't see any landing.

[linuxgurugamer]

What, no comments about the flat earth?

Re:Beautiful by the numbers launch / deploy / land

[WhiplashII]

The space shuttle sonic booms were lethal, but only in a contained area over the ocean. That's why they had to clear that area of ships before launch.

The issue is that the shuttle (like most rockets) didn't fly straight up, it went in a curve. That creates a focus point for the shockwave, which makes it MUCH bigger.

Nothing more than a scrapyard

[DerekLyons]

Until they start reflying, all Musk is accomplishing is a very expensive method of collecting scrap aluminum.

Re:Nothing more than a scrapyard

[tsotha]

Didn't they announce the flight in early October would be the first reuse? We shall see. I'm assuming they'll be able to reuse the LEO stages, but I wonder if the GTO stages will ever be in good enough shape to rely on.

Re:Nothing more than a scrapyard

[DerekLyons]

Didn't they announce the flight in early October would be the first reuse?

No. They announced the first re-use would be in "September or October", but no flight or customer has been specifically identified. And it's worth noting that originally the first re-use would be in "May or June" (of 2016).

Re:Nothing more than a scrapyard

[tsotha]

I'm pretty sure a flight was identified in the last week; I just don't remember where I read it.

Re: Beautiful by the numbers launch / deploy / lan

[Anonymous Coward]

https://m.youtube.com/watch?v=FCCyVCvN2bo

The logical next step

[93 Escort Wagon]

Attempt to land the Falcon rocket on a white 18-wheeler.

Daylight landing?

[Anonymous Coward]

I wonder why both land based landings occurred during the night? Is there something about Cape Canaveral location low earth orbit that makes nighttime launches more likely?

Re:Daylight landing?

[Anonymous Coward]

Because the launch window was at night. So they have to land at night.

Re:Beautiful by the numbers launch / deploy / land

[Anonymous Coward]

I used to live in rural Texas. Large explosions are considered a Good Thing there. No one from SpaceX will ever have to pay for their own drinks, believe me.

Re:Beautiful by the numbers launch / deploy / land

[Anonymous Coward]

They clear the area downrange so the debris raining down from a failed launch doesn't kill anyone. Everything you've said is baloney.

*yawn*

[DerekLyons]

Yeah, go Google that and get back to me. (Hint I already did what you are too lazy to do - check the facts.)

Re:*yawn*

[tsotha]

There's no reason to be a dick, Derek. I did google it and couldn't find anything. Otherwise I would have provided a link.

Yes, there is a reason

[DerekLyons]

Yes, there is a reason to be a dick - because a certain someone kept insisting that something had happened, but couldn't provide a link. When someone acts like an idiot, they get treated like an idiot.

Re:Yes, there is a reason

[tsotha]

Heh heh. You really haven't changed over the years.

Re:Yes, there is a reason

[DerekLyons]

No idea who you are. But no, I still have a low tolerance for such nonsense. Always will.

Nice

[bobibleyboo]

Freaking awesome!