# SpaceX: Another Falcon 9 ground pad landing

• SpaceX
Mentor
Second attempt on land today, second success: A Falcon 9 delivered a Dragon capsule on its way to the ISS, and the first stage returned to the launch site and landed.

Track record for the "Full Thrust" version so far:
2 out of 2 landings on ground successful
3 out of 5 landings on sea successful. One failure came from imprecise timing of thrust, one from an engine that performed worse than expected ran out of oxygen.

SpaceX plans to re-launch a stage (the second one that landed) around September, just two months away. Payload is not fixed yet, at least not made public. SES, a communication satellite operator, is interested, and there is an SES flight scheduled for September and also one for October.

Two more launches are planned for August, but it is unclear if those plans are still up to date. SpaceX frequently shifts launches back over time. In December, or early 2017, we might see the first Falcon Heavy launch and a demonstration launch (abort test) for the Dragon 2 capsule, which is designed for manned missions.

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Monsterboy, mheslep, 1oldman2 and 2 others

Gold Member
... one from an engine that performed worse than expected.
I thought that was the initial conclusion but Elon Musk later corrected it to "Looks like early liquid oxygen depletion caused engine shutdown just above the deck". I seem to remember having seen some later analysis which said that automatic mixture adjustment had for some reason switched to a slightly more oxygen-rich ratio than usual, which resulted in it running out a little earlier than originally expected, but I can't find that right now - anyone know where that appeared?

Mentor
You are right. Well technically zero thrust is "worse than expected" I guess.

Gold Member
From some Googling, I think I'm probably confusing the oxygen-rich explanation with two other cases:
1. A recent ULA Atlas 5 problem where the first stage cut off early because of oxidiser depletion and the second stage was barely able to correct for it.
2. A previous SpaceX problem around 2010 where fuel ran out just before oxygen, risking damage through an oxygen-rich spike causing elevated engine temperatures.

So the "liquid oxygen depletion" in the SpaceX case was probably simply a case of not quite having enough left by a tiny and unpredictable margin.

1oldman2
jackwhirl
I love that SpaceX has been so open with both their successes and failures. It's been a real treat watching them improve incrementally and I applaud both their audacity and tenacity.

1oldman2 and NowsTheTime
1oldman2
Good to see the IDA2 made into orbit.

Homework Helper
This fifth recovered booster fills their storage hanger. They need to find another one.
They are also looking for two more landing pads - so they can land three boosters simultaneously.

Actually, I thought this last mission was more interesting because of the ISS docking adapter it carried. They lost the first one June 2015. It would have been bad news if they had lost this one as well.

1oldman2
Mentor
As far as I know two boosters got moved out. One is supposed to stay somewhere for display, not sure about the other one. But that tweet is not so far off - they either have to start launching re-used boosters in a rapid rate, or find some other place to put them.

1oldman2
Gold Member
They are also looking for two more landing pads - so they can land three boosters simultaneously.
Just to be clear, this is for Falcon Heavy which is effectively three Falcon 9 boosters strapped together in a row, so from a single launch there would be three separate boosters coming back.

1oldman2
One goes on display at headquarters in Hawthorne California, the other is being studied for damage, I believe in Texas.

1oldman2
Just to be clear, this is for Falcon Heavy which is effectively three Falcon 9 boosters strapped together in a row, so from a single launch there would be three separate boosters coming back.
I believe the core stage has to do a barge landing, the boosters fly back to land.

Gold Member
I believe the core stage has to do a barge landing, the boosters fly back to land.
The side boosters certainly get to go home early, but I think there's a hope that the core stage may sometimes be able to fly back too.

Mentor
It will depend on the mission. The Falcon Heavy core stage will be faster and further downrange, so flying it back really lowers the payload capability. Still better than with a Falcon 9, but I think reflying the cores has to be very reliable to make that a good option.

1oldman2
Gold Member
I wonder if there will also be the opposite case, requiring three drone ships. I think the other GCU ship name from "Player of Games" seems to be "Flexible Demeanour", but there are some great names in "The State of the Art" such as "Funny, It Worked Last Time...", "Only Slightly Bent" and "Ultimate Ship The Second".

mheslep and 1oldman2
Gold Member
Nice discussion and exciting news.

1oldman2
Gold Member
It will depend on the mission. The Falcon Heavy core stage will be faster and further downrange, so flying it back really lowers the payload capability. Still better than with a Falcon 9, but I think reflying the cores has to be very reliable to make that a good option.
Flying the booster "back" means back to the launch pad? With a "Still Love You" landing at sea, further downrange should simply mean the barge goes further downrange. Or eventually a ground landing in, say, the Canaries (~same latitude, 3857 miles downrange). No?

rootone
Might work, and if that is achievable then West African countries, (and maybe Portugal), is possible.

person_random_normal
the satellites carried by the spaceX rockets , what do they do, that is -what commercial use ?

1oldman2
Homework Helper
the satellites carried by the spaceX rockets , what do they do, that is -what commercial use ?
It's a wide variety. The most recent one resupplied the International Space Station. They have also done communication and military satellites.
Here is there mission list: http://www.spacex.com/missions
You can do a Google on each one. For example, Google "Jason-3" and you'll discover it's an ocean surface topography survey.

Mentor
Flying the booster "back" means back to the launch pad? With a "Still Love You" landing at sea, further downrange should simply mean the barge goes further downrange. Or eventually a ground landing in, say, the Canaries (~same latitude, 3857 miles downrange). No?
"Back" means back to the launch site (the landing pad is not directly the launch pad, but nearby). Yes, further downrange means further away on sea. The next land is way too far away to reach it with the first stage, even with a Falcon Heavy (FH).
the satellites carried by the spaceX rockets , what do they do, that is -what commercial use ?
Falcon 9 can launch everything apart from the heaviest satellites, Falcon Heavy will be able to launch those as well (and have some good margin for even heavier satellites, which cannot be launched yet). In general, missions to geostationary transfer orbit (GTO, where the satellites then enter a geostationary orbit on their own) are the most profitable missions, as many rockets can deliver satellites to low Earth orbit but the extra speed to GTO makes the missions more interesting. Satellites to GTO (mainly communication) also tend to be quite heavy.

Gold Member
"Back" means back to the launch site (the landing pad is not directly the launch pad, but nearby). Yes, further downrange means further away on sea. The next land is way too far away to reach it with the first stage, even with a Falcon Heavy (FH)...
Right, thanks. I see now that of course distance down range for the booster would be all about the delta V of the stage. While Heavy booster will have much more thrust than 9, given the Heavy payload I doubt if the delta V for Heavy booster changes much from 9 for the same orbital destination. If distance down range for booster is now, I dunno, a couple hundred miles, then Africa is orders of magnitude beyond reach.

Mentor
Here is a unofficial simulation of Falcon Heavy where all cores return to launch site (13.5 tons payload to low Earth orbit). The boosters separate at 2:43 video time: 87 km altitude, 70 km downrange, 2.1 km/s speed. The central core separates at 3:04, 116 km altitude, 106 km downrange, 2.6 km/s.
If the central core can go to the drone ship, it can throttle down its thrust a bit more while the boosters are still attached - the boosters separate earlier and the central core can accelerate the second stage more.

mheslep
enorbet
It is easy for people used to the news reporting new feats of expertise and technology to dismiss this as simply "a neat trick" but IMHO it is an actual game-changer of which the effects will ripple forever. As bad as many obstacles to Space Travel indeed are, the single greatest obstacle is still expense. Bringing that down by such a substantial degree affects the ability to gain the experience required to address all other obstacles. Elon may have some slightly paranoid ideas about AI but he surely knows how to assemble a team and get the most from them.

Mentor
We'll see how much it will bring down costs. The expendable Falcon 9 is significantly cheaper than other rockets, but that is not related to any reusability. Landing the rocket is only the first step - we'll have to see if they can fly the stages again reliably without exchanging and repairing too many components. And then we'll see how much cheaper those launches will be. SpaceX talked about a 30% reduction in launch costs, that is not much. It is a new technology, of course, future improvements are likely.

jackwhirl
jackwhirl
Landing the rocket is only the first step - we'll have to see if they can fly the stages again reliably without exchanging and repairing too many components.
Additionally, recovered rockets can be examined to identify areas with accelerated wear. Future revisions can reinforce those areas. This sort of iteration is only possible with recovery.

Gold Member
actual game-changer of which the effects will ripple forever.
Bringing the boosters back is the first part of changing the launch game. Successfully reusing them without significant rework is the second part. Heat, vibration loads on launch and recovery, I think, keep that from being simple. So far the 2nd part has not been done. Standing by.

Gold Member
Here is a unofficial simulation of Falcon Heavy where all cores return to launch site (13.5 tons payload to low Earth orbit). The boosters separate at 2:43 video time: 87 km altitude, 70 km downrange, ...

At the point of separation, their continued ballistic path seems to have them on the surface at ~470 km downrange. The core booster, seems to make it out to ~600 km downrange (see simulation elapsed time 3:15), or perhaps in range of Bermuda. I imagine the real problem with following the arc further downrange, even if there happened to be an island fortuitously placed, as opposed to cutting velocity and heading back, is the heat of re-entry at maximum velocity.

enorbet
We'll see how much it will bring down costs. <snip>. SpaceX talked about a 30% reduction in launch costs, that is not much. It is a new technology, of course, future improvements are likely.

I contend that a 30% reduction, as you say, is hopeful still but wouldn't write that off as "not much" since -

1) It is the first reduction of that magnitude not sacrificing safety or performance. At the very least it proves efficient savings are possible and "proof of concept" is an important first step.

2) If they do achieve 30% net reduction just in this specific area of cost this improves the field by making new "players" less dismissive and more inclined to join in the business of Space Flight. It seems less risky and more doable much like the spurt of growth in Aviation after Curtiss entered the field. Soon after, airplanes, which only a few years before were abject failures even for the most advanced and experienced minds, became ubiquitous. Nobody is likely to build a booster in a barn but the progression follows a similar path.

3) It furthers the advancement into a field where little has been "off the shelf" and one-of-a-kinds not only cost more but tend to add up in nasty ways.

SpaceX has already won $4.2 Billion in contracts from NASA and recently another$1 Billion from Google and Fidelity. Even a 2% gain in profitability encourages investors as well as competitors and they haven't even gone Public yet.

First steps are most often small steps but without a first step away from the accepted norm, status quo prevails and progress stagnates. I suppose it is still speculation on my part but the odds do look quite good especially considering the opposite effect of SpaceX "biting off more than it can chew" and falling on it's face from over-reaching. "Nothing succeeds like success", right?

Mentor
I contend that a 30% reduction, as you say, is hopeful still but wouldn't write that off as "not much" since -
It is not much compared to the general range of payload prices. A typical price tag on "just deliver a few tons to low Earth orbit" is in the range of $10,000 to$20,000 per kg, depending on the rocket and the payload mass. SpaceX charges about \$5,000. That is a factor 2-4.

enorbet
Of course, mfb, I understand those numbers but I wonder if you're considering that given a return to flight-ready there is no currently known reason that the recovery cannot continue for many iterations. It may not be log like compound interest, but it does add up. Furthermore while the term "bottom line" has become commonplace in the lexicon, management knows it is the next to bottom line that is what is important - variable costs. A progressive reduction of that line insures a growing bottom line and while government funded organizations like NASA are certainly very concerned with cutting costs, it is rare that their existence depends on it once they get big. Private Enterprise, OTOH, lives and dies by that bottom line and since variable costs is the only area where control is possible and practical, they hire experts in that field whose concerns never soften with growth. NASA instead hires consultants great with grants and funding.

I have little to go on but the nature of technology business but every aspect of that, whether airplanes, jets, computers, etc. follows a similar path. Once commercialized and made possible for private startups to seriously compete, rapid growth and innovation follows. I'm far more interested in Science than Business but I am also aware that nothing of much import happens without finances and I see "reusable" proof-of-concept as a start of an extremely important progression, even if that first step proves to be minimal but also cumulative, not to mention, inspiring.

Gold Member
Here's an article on the potential cost savings from reuse, including the various factors which make this difficult to estimate at this stage:
http://spacenews.com/spacexs-reusable-falcon-9-what-are-the-real-cost-savings-for-customers/
One of the assumptions appears to be that in the short term, while reuse is still somewhat experimental, any savings achieved via successful reuse are mainly expected to increase the profit margin for SpaceX rather than being immediately passed on to the customer, but it has been suggested that SpaceX may initially provide a discount for customers who accept a launch on a reused first stage.

Mentor
Of course, mfb, I understand those numbers but I wonder if you're considering that given a return to flight-ready there is no currently known reason that the recovery cannot continue for many iterations.
That is considered for the 30%. Reducing the cost by 50% to 75% (Falcon 9 expendable) is a larger effect than reducing it by 30% (reusability of Falcon 9).

A mature, fully reusable rocket (the second stage of Falcon 9 is not reusable) can potentially decrease costs much more, but Falcon 9 won't be such a system, at least not in the next years.

enorbet
Thank you Jonathan and mfb for further clarification. I suppose in one respect it's a "how far back you want to go" rather than a "first step" since it is all a continuum, but even within that there are milestones. Robert Goddard's determination and willingness to move residence and risk furious neighbors and possible incarceration is one of those, I think you'd agree. (makes me wonder how Homeland Security would react to an analogous activity today. I used to get my Father to buy KNO3 at the local pharmacy for the "caramel candy" propellant I was using for a time around 1961 for my model rocketry experiments and I very much doubt that is possible anymore, let alone the Zinc dust, Magnesium dust, and Sulphur I could get through the US Postal Service then .)

While reusable boosters pale in comparison to Goddard's contribution, that may still prove to be a key catalyst to Proactive Dreamers who grab onto anything encouraging to make dreams real. It is my understanding that the main developer of the Ion Engine pursued that goal because Scotty ( I'm givin' her all we got now, Captain) was in awe of an alien ship with Ion Drive and apparently his story is not a solo act. Dreamers, and Elon Musk, for all his accomplishments I think must be considered such given all of his ventures and perhaps especially the unrealistic Mars One goals. That said, Mars One despite it's all too obvious flaws, has and is still stimulating those who don't know or can't admit how far away that technology really is. Often, such people can be breakthrough inventors just because they are unaware "it can't be done". Then, of course they lean on engineers to do the impossible :)

NowsTheTime
SpaceX has truly made remarkable strides in the field of rocketry. It's crazy to think that, years ago, we had no choice but to let first stage boosters plummet to the Earth's surface. Seeing a massive rocket land vertically after sending a payload into outer space is simply enchanting.

jackwhirl