Author Topic: SpaceX vs BlueOrigin - Whose Approach / Business Strategy is Better?  (Read 122256 times)

Offline Darkseraph

  • Full Member
  • ****
  • Posts: 462
  • Liked: 175
  • Likes Given: 86
I slightly prefer Blue Origins statement on its vision to SpaceX (and by extension, Zubrin's vision).

Destination doesn't solve the problem of spaceflight. You can be destination driven and pick Titan as the next place humans should go. It doesn't matter that a destination focuses the effort in "Apollo" mode. The problem is still cost. Blue is working on fixing that rather than prescribing a destination as a fix to societies existential malaise.

It is open ended, and I actually like that. When you solve the problem of cost, you solve the problem of destination. NASA can then send astronauts to multiple destinations within its current budget (or less) without constant internecine warfare between Moon-First, Mars First or Wherever-First groups. The technology that SpaceX is developing will obviously help go to these other places too but there obsession with a single destination is of less interest to me than expanding human presence throughout the solar system.
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline A_M_Swallow

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8173
  • South coast of England
  • Liked: 254
  • Likes Given: 106
They can fight it to the end of time if they want, but people will keep using the abbreviated company name.
If Musk can convince people that the abbreviation for Space Exploration Technologies Corporation is "SpaceX" then Bezos still has a chance to get "Blue" to catch on.

Blue sounds like Blues, a type of music.

However IMHO BlueO might work as the nick name of a rocket company.

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 12777
    • Space Launch Report
  • Liked: 3548
  • Likes Given: 607
Blue is a decade behind, but it may be leapfrogging SpaceX on the propulsion side with BE-3 and BE-4.

Not sure how you figure that.  The Merlin 1D ithrust-to-weight ratio is the highest ever achieved for a rocket engine, has a 70-100% throttle capability, and has been constantly evolved and matured over more than a decade.  For domestic use, which I would call Earth local space, the Merlin 1D is hard to beat on any metric.

Plus SpaceX is well into developing their own methane fueled engine, the Raptor, which will have almost 3X the amount of thrust the BE-4 does.
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle

Offline nadreck

As human beings, Elon Musk and Jeff Bezos are quite different, but in their roles in their business ventures there are probably more similarities than differences. That said Blue Origin and SpaceX are proceeding along very different paths with many similar technical goals but different business strategies.

SpaceX while potentially could draw on Elon's other sizable assets for cash at some future date, seems unlikely to and  has managed to raise several times the money Elon has put into it in equity and has significant cash flow from its operations.

Blue has no cash flow and while it potentially could grab more money from its founder than SpaceX could from Elon, it has been proceeding at a slower funds burning pace but as well as slower development pace.

SpaceX will probably do more than Blue, but it is yet to be seen whether they can accomplish their stated goals just as Musks very lofty goals for all his post PayPal ventures may not all come to fruition.

I don't see a difference between Raptor and BE-4 in terms of what it will bring either company. Nor do I see there being a tangible race between Falcon and Vulcan, as far as I can tell Falcon will more or less cross the finish line in that race in the next year or so, while Vulcan will still have no track record when metal is being bent on the first rockets to use Raptors and FH will have the track record needed to allow it pricing power against initial flights of the Vulcan.(ie the ability to preserve high margins until the Vulcan has a track record)

When FH launches it really widens the gap that Blue just closed a little, and it really ups the ante with capabilities to compete with the heavy end of launchers still at a price point below the current ones and with no consideration for any level of reuse.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline Lars-J

  • Senior Member
  • *****
  • Posts: 3454
  • California
  • Liked: 2690
  • Likes Given: 1700
Blue is a decade behind, but it may be leapfrogging SpaceX on the propulsion side with BE-3 and BE-4.

Not sure how you figure that.  The Merlin 1D ithrust-to-weight ratio is the highest ever achieved for a rocket engine, has a 70-100% throttle capability, and has been constantly evolved and matured over more than a decade.  For domestic use, which I would call Earth local space, the Merlin 1D is hard to beat on any metric.

Plus SpaceX is well into developing their own methane fueled engine, the Raptor, which will have almost 3X the amount of thrust the BE-4 does.
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle

This talk of greatest efficiency is very ironic, coming from the greatest fan of solid rockets on these forums.  ;D

Offline RocketGoBoom

  • Full Member
  • **
  • Posts: 241
  • Idaho
  • Liked: 211
  • Likes Given: 215
Financing differences:

Revenue of Space X: 0.5B
Valuation of SpaceX: 12B
Shares of Musk: unknown, after lots of rounds.


I think your revenue estimates fro SpaceX are likely too low.
 
The contract for development of commercial crew is about $2.6 billion spread over a few years. That contract by itself is likely over $500 million per year in revenue for SpaceX.

I would guess that their total revenue per year is closer to $1 billion. It really depends on all of those 50+ contracts for future sat launches and the schedule for payments.

Offline LastStarFighter

  • Full Member
  • **
  • Posts: 225
  • Europa
  • Liked: 68
  • Likes Given: 10
Blue is a decade behind, but it may be leapfrogging SpaceX on the propulsion side with BE-3 and BE-4.

Not sure how you figure that.  The Merlin 1D ithrust-to-weight ratio is the highest ever achieved for a rocket engine, has a 70-100% throttle capability, and has been constantly evolved and matured over more than a decade.  For domestic use, which I would call Earth local space, the Merlin 1D is hard to beat on any metric.

Plus SpaceX is well into developing their own methane fueled engine, the Raptor, which will have almost 3X the amount of thrust the BE-4 does.
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle

Agreed. There is so much more to determining how good an engine is besides its thrust to weight ratio. Honestly I don't recall any other engines ever being associated with a thrust to weight ratio besides the Merlin.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27019
  • Minnesota
  • Liked: 6911
  • Likes Given: 4873
Blue is a decade behind, but it may be leapfrogging SpaceX on the propulsion side with BE-3 and BE-4.

Not sure how you figure that.  The Merlin 1D ithrust-to-weight ratio is the highest ever achieved for a rocket engine, has a 70-100% throttle capability, and has been constantly evolved and matured over more than a decade.  For domestic use, which I would call Earth local space, the Merlin 1D is hard to beat on any metric.

Plus SpaceX is well into developing their own methane fueled engine, the Raptor, which will have almost 3X the amount of thrust the BE-4 does.
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle
RLVs are all about mass fraction. Merlin 1D likely has much better T/W ratio than either of those engines.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27019
  • Minnesota
  • Liked: 6911
  • Likes Given: 4873
Blue is a decade behind, but it may be leapfrogging SpaceX on the propulsion side with BE-3 and BE-4.

Not sure how you figure that.  The Merlin 1D ithrust-to-weight ratio is the highest ever achieved for a rocket engine, has a 70-100% throttle capability, and has been constantly evolved and matured over more than a decade.  For domestic use, which I would call Earth local space, the Merlin 1D is hard to beat on any metric.

Plus SpaceX is well into developing their own methane fueled engine, the Raptor, which will have almost 3X the amount of thrust the BE-4 does.
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle

Agreed. There is so much more to determining how good an engine is besides its thrust to weight ratio. Honestly I don't recall any other engines ever being associated with a thrust to weight ratio besides the Merlin.
If you don't recall, then you aren't very familiar with this field. NK-33's T/W ratio was often touted. T/W ratio is key to getting a good mass fraction, which is essential for VTVL RLVs, especially if you're doing return-to-launchsite for the first stage.

Getting good Isp alone is WAY over-rated by the spaceflight enthusiast community. Mass fraction is just as important if not more so for an RLV.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27019
  • Minnesota
  • Liked: 6911
  • Likes Given: 4873
Like their founders Elon Musk and Jeff Bezos, SpaceX and Blue Origin have differences in their respective approaches, strategies, and paths to the future.

Whose seems likely to bear better fruit, extrapolating purely based on what we currently know of them?

SpaceX seems to have interwoven iterative R&D flight-testing with immediate servicing of govt launch contracts and private payload launches, for revenue purposes. In that interest, it has sought to achieve orbital flight first, then reusability, and finally leaving crewed flight for last.

Blue Origin has kept itself more private and undercover, while pursuing a focus on manned spaceflight for space tourism, along with reusability, while deferring higher orbital flight velocities for later. Meanwhile, it has signed R&D deals with other SpaceX competitors such as ULA with its specialization for cargo delivery, to defray costs.

What are the various pro's and cons of the technical and business strategies of each?

To me, one advantage in the Blue Origin approach may be the ability to rush into the mass market for space tourism sooner than SpaceX could. For basic space tourism, suborbital flight is all you need to start cashing in. Orbital spaceflight for tourism purposes may offer diminishing returns relative to the cost expenditure. Because suborbital brings spaceflight directly to the masses much sooner, then Blue Origin could get the early adopters and early enthusiasts who are willing to pay more to enjoy the experience sooner.

What are the opinions on how the market for suborbital space tourism stacks up revenue-wise, in comparison to conventional satellite launches and ISS resupply? Perhaps only time will tell, and may throw up some surprises.
Their technical approaches are actually quite similar. Both use aerosurfaces, both are transitioning to methane/LOx reusable first stages, both have done several VTVL demo flights with multiple demo vehicles. (and both have had crashes/explosions... this stuff is hard)

Their business plans are quite different, and in many ways don't overlap very much at all. Remarkably independent, actually. Blue is going after suborbital tourism, SpaceX is going after orbital spacelaunch. In the near-term, there's a lot (a LOT) more revenue in SpaceX's approach, so SpaceX should be able to bootstrap. But Bezos does have more personal funds to draw on than Musk, so Blue Origin isn't at risk of running out of money (though they are at risk of not being terribly relevant if they have too much "Gradatim" and not enough "Ferociter"), and Blue Origin started out on the right technical path of VTVL while SpaceX was still just doing Falcon 1 and trying to do parachute recovery of the first stage (which turned out to be a dead-end), but SpaceX has overcome that initial handicap and are already a major launch provider likely to demonstrate first stage landing in a matter of 1-4 months.

Blue Origin could end up being fully successful in their original business plan (fully reusable passenger suborbital spaceflight) while being beat to the punch to first-stage orbital reuse by several years.

I hope both are successful.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 8180
  • Australia
  • Liked: 2949
  • Likes Given: 707
As human beings, Elon Musk and Jeff Bezos are quite different, but in their roles in their business ventures there are probably more similarities than differences.

I don't know what you're trying to say here... Jeff isn't a walk around manager who has to have his finger in everything like Elon. I can't even imagine Elon running a company like Amazon. You won't be hearing any cutesy stories about Jeff teaching himself rocketry from scratch. You really won't find two more different entrepreneurs. This is a good thing in my opinion.

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Online spacenut

  • Senior Member
  • *****
  • Posts: 2150
  • East Alabama
  • Liked: 310
  • Likes Given: 195
One thing I like about BO, is the BE-3 engine.  That engine can do a lot, and if developed for vacuum, It could send large payloads to Mars or the Moon and it is reusable, so refueling an in space BE-3 truck could be used by everyone. 

SpaceX is way ahead in orbital rocketry though.  Making it reusable is the hard part. 

I've often wondered what a BE-3 based second stage for Falcon Heavy could do. 

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27019
  • Minnesota
  • Liked: 6911
  • Likes Given: 4873
It's worth noting that NEITHER SpaceX nor Blue Origin have much operational experience with reusable rockets. Blue Origin will launch a rocket 2-3 times and either retire it or it explodes on the last flight. SpaceX does slightly better with Grasshopper and F9Rdev1, getting 8 and 5 launches, respectively. But neither is really gas and go.

Masten Aerospace and XCOR are arguably well ahead on that front, though orders of magnitude smaller (Xombie and EZ-rocket, etc).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1554
  • Liked: 1732
  • Likes Given: 197

BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle
For comparing Merlin and BE-3, engine efficiency (ISP) is a bogus metric, since the higher ISP of Be-3 is obtained with less dense fuel, requiring larger tanks.  You can't just ignore this. Compare the Falcon first stage to New Shepard, both designed to take off from the ground and reach a 100 km or so altitude.  The ISP of BE-4 is unpublished, as far as I know, but assume it's similar to J2-X at 421 sec.  The Merlin is 310.

From the calculations upthread, New Shepard has an estimated empty mass of 10t, and holds about 30t of fuel.  So the delta-V will be 421 * 9.8 * ln(4) = 5.7 km/sec.  For the Falcon first stage, it's suspected the empty mass is about 30t, and it's known to hold 386t of fuel (without sub-cooling).  So the total delta-V is 310*9.8*ln(416/30), or about 7.9 km/sec.  So in terms of delta-v provided per stage, the stage using Merlin is far more efficient than the stage using a BE-3.

Now in terms of delta-V per unit mass, hydrogen can be better.  But your inference, therefore less mass at liftoff, therefore less money, does not follow.  The saving in first stage mass may not save much money (aluminum and kerosene are cheap), while the additional expenses to handle hydrogen may be considerable.   It's the sum of these costs that counts, not either of these in isolation.  For example, the Delta-IV heavy and the Falcon Heavy have similar performance.  The Delta-IV has a hydrogen upper stage, which indeed reduces the liftoff mass (733 tons compared to Falcon Heavy's 1463 tons).  But by all accounts the Falcon Heavy will be much cheaper, despite its larger mass.

In fact, the empirical evidence is opposite your claims.   Rockets with hydrogen upper stages are known for being expensive (Atlas, Delta, H-II, Ariane).  The low cost rockets (Falcon, Soyuz, Proton) do not use hydrogen in the upper stages.

Offline Llian Rhydderch

  • Full Member
  • ****
  • Posts: 855
  • Terran Anglosphere
  • Liked: 547
  • Likes Given: 5288
The approaches of both companies are thoroughly entrepreneurial, taking risk against a profoundly uncertain future, where both entrepreneurs are risk takers--willing to put their own resources at risk in the venture--and are quite optimistic about their ability to make a difference in the state of the world going forward.

Basically, it is as if both see the state of the world (SOTW) as it is and has been since the dawn of the space age (expensive space access, few could go, absurdly expensive cargo transport rates, a government-led enterprise, etc.) and they see a different SOTW that they can help bring about.

Beyond that, to the question of the OP, we simply cannot know which is the better business strategy.  All entrepreneurial outcomes are generated in the very process, over time, of working out in the midst of myriad other individuals working out their own way, on both sides: the providers of space transport services and those who might use such services, the producers and the consumers.

It will be exciting to watch!   8)
 
However, this being an internet forum, where much speculation is acceptable, I will predict that this thread will have hundreds of responses before it is over as many try their hand at arguing for one strategy over the other--Blue vs. SpaceX.  Which, as a side benefit, will generate clicks for NSF and Chris.   ;)
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
"You would actually save yourself time and effort if you were to use evidence and logic to make your points instead of wrapping yourself in the royal mantle of authority.  The approach only works on sheep, not inquisitive, intelligent people."

Offline Kryten

  • Full Member
  • ****
  • Posts: 491
  • Liked: 217
  • Likes Given: 26
Isn't asking this question premature? We have only vague hints of what Blue's business strategy even is past New Shepard, there's very little to make a comparison from.

Offline TrevorMonty


BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle


From the calculations upthread, New Shepard has an estimated empty mass of 10t, and holds about 30t of fuel.  So the delta-V will be 421 * 9.8 * ln(4) = 5.7 km/sec.  For the Falcon first stage, it's suspected the empty mass is about 30t, and it's known to hold 386t of fuel (without sub-cooling).  So the total delta-V is 310*9.8*ln(416/30), or about 7.9 km/sec.  So in terms of delta-v provided per stage, the stage using Merlin is far more efficient than the stage using a BE-3.


The 10t dry mass seems high for 30t fuel. Centuar is 2t for 20t. The landing equipment does add weight but I doubt it is 5-7t.
There doesn't appear to be any load on tank as weight from capsule support ring is transferred direct legs and engine section.

I'm picking it uses autogenous, true gas and go with no He.

The capsule gross weight is 8000lbs. Quote from Blue.
« Last Edit: 11/26/2015 02:23 AM by TrevorMonty »

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1554
  • Liked: 1732
  • Likes Given: 197

BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle


From the calculations upthread, New Shepard has an estimated empty mass of 10t, and holds about 30t of fuel.  So the delta-V will be 421 * 9.8 * ln(4) = 5.7 km/sec.  For the Falcon first stage, it's suspected the empty mass is about 30t, and it's known to hold 386t of fuel (without sub-cooling).  So the total delta-V is 310*9.8*ln(416/30), or about 7.9 km/sec.  So in terms of delta-v provided per stage, the stage using Merlin is far more efficient than the stage using a BE-3.


The 10t dry mass seems high for 30t fuel. Centuar is 2t for 20t. The landing equipment does add weight but I doubt it is 5-7t.
There doesn't appear to be any load on tank as weight from capsule support ring is transferred direct legs and engine section.

I'm picking it uses autogenous, true gas and go with no He.

The capsule gross weight is 8000lbs. Quote from Blue.

Agree 10t seems high, but the engine is rated to a minimum thrust of 20,000 lb force.   Then, you can see it hover, or close enough that makes no difference, in the video.  So the empty mass must be more than 9t.

Online Coastal Ron

  • Senior Member
  • *****
  • Posts: 3409
  • I live... along the coast
  • Liked: 2169
  • Likes Given: 2675
BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.

Higher efficiency means nothing if the entire system is not efficient.  For instance, the Shuttle SSME's were very efficient, but on a $/kg to orbit basis the Shuttle system was pretty expensive.  And cost is the most important factor limiting us from doing more in space.

Blue Origin does appear to be focused on cost too, so that is a win for lowering the cost to access space.  And they are helping ULA, one of the most expensive launch providers, to lower their costs too.  But while we know what the costs are for getting mass to space using Merlin 1D engines, we don't yet know what it will be with BE-3 or BE-4 engines.  Let's hope Blue Origin surprises us like SpaceX did when they announced their prices.

Quote
That means less thrust at liftoff, which means less money.

I'm not a rocket engineer, but are you implying that the closer to zero thrust you go the better the engine?

Quote
The BE-3 deep throttling is also impressive and something that Merlin cannot do.

Features without a need are useless.  While the New Shepard requires engines with the BE-3 capabilities, Falcon 9 does not.  But knowing what the BE-3 and BE-4 engines are designed to do, that does provide a window into what Blue Origin plans on doing in the future, and as the New Shepard has shown that future is exciting.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline leaflion

  • Full Member
  • *
  • Posts: 102
  • United States
  • Liked: 50
  • Likes Given: 17

BE-4 and BE-3 both have higher efficiency than Merlin.  This will provide more payload, especially to deep space, for the same rocket mass.  That means less thrust at liftoff, which means less money.  The BE-3 deep throttling is also impressive and something that Merlin cannot do.

 - Ed Kyle
For comparing Merlin and BE-3, engine efficiency (ISP) is a bogus metric, since the higher ISP of Be-3 is obtained with less dense fuel, requiring larger tanks.  You can't just ignore this. Compare the Falcon first stage to New Shepard, both designed to take off from the ground and reach a 100 km or so altitude.  The ISP of BE-4 is unpublished, as far as I know, but assume it's similar to J2-X at 421 sec.  The Merlin is 310.

From the calculations upthread, New Shepard has an estimated empty mass of 10t, and holds about 30t of fuel.  So the delta-V will be 421 * 9.8 * ln(4) = 5.7 km/sec.  For the Falcon first stage, it's suspected the empty mass is about 30t, and it's known to hold 386t of fuel (without sub-cooling).  So the total delta-V is 310*9.8*ln(416/30), or about 7.9 km/sec.  So in terms of delta-v provided per stage, the stage using Merlin is far more efficient than the stage using a BE-3.

Now in terms of delta-V per unit mass, hydrogen can be better.  But your inference, therefore less mass at liftoff, therefore less money, does not follow.  The saving in first stage mass may not save much money (aluminum and kerosene are cheap), while the additional expenses to handle hydrogen may be considerable.   It's the sum of these costs that counts, not either of these in isolation.  For example, the Delta-IV heavy and the Falcon Heavy have similar performance.  The Delta-IV has a hydrogen upper stage, which indeed reduces the liftoff mass (733 tons compared to Falcon Heavy's 1463 tons).  But by all accounts the Falcon Heavy will be much cheaper, despite its larger mass.

In fact, the empirical evidence is opposite your claims.   Rockets with hydrogen upper stages are known for being expensive (Atlas, Delta, H-II, Ariane).  The low cost rockets (Falcon, Soyuz, Proton) do not use hydrogen in the upper stages.

Did anyone ever say that hydrolox was cheaper than kerolox?  It is higher performance.

Any guesses on BE-3 TWR?

Tags: