A bad week for space enthusiasts.

View 849 Sunday, November 02, 2014

All Souls Day

“I have observed over the years that the unintended consequences of social action are always more important, and usually less agreeable, than the intended consequences.”

Irving Kristol

“Transparency and the rule of law will be the touchstones of this presidency.”

President Barack Obama, January 31, 2009

Tuesday will be one of the most important elections of this Millennium. A Republican win will not be decisive over time, because it will not be a mandate: a Republican win will be a public objection to the leftward plunge of the Democratic Party. Unfortunately it will be construed by Establishment Republicans as a great deal more than that, and that will cause problems, but they are soluble problems. A Republican Thumping – unlikely given the polls – would be a disaster for the cause of limited government. If the big government party can win despite the sheer incompetence of the past few years, the Republic will have to sink very low indeed before it can turn back from centralization and control by increasingly arrogant and incompetent bureaucracy.

It appears that the Ebola threat remains under control. Little of that control is due to competence. We do not really have an understanding of all the strains of Ebola, the mutation rate that could follow a large outbreak of the virus in a hitherto unfamiliar host environment, or indeed all the transfer mechanisms. We have been fortunate enough to find that the general theory – that the virus can become virulent only after it so infects the human host that obvious symptoms are displayed – has so far been predictive. Of course it is very much in the interest of the virus to be transmitted before any visible symptoms are displayed; or if you prefer, the strains of the virus that can infect before the host subject displays symptoms have a far higher chance of survival; that would be a far more ‘fit’ virus than one that has to render the host half dead before it can spread to a new host.

We are betting heavily that such mutations are not taking place in this current outbreak. I have no way to estimate the probabilities here, and wouldn’t even with a great deal more data on what’s going on in West Africa. The Administration theory is that quarantine is an ineffective strategy. We are better off fighting the disease in Africa than in the United States, and putting difficulties in the way of physicians returning from the plague area will discourage them from going there at all. These are, after all, trained professionals and they will act properly.

The behavior of several of these professionals indicates that they are very certain that they can’t be contagious before displaying symptoms, and they believe this so strongly that they feel justified in defying any instruction to the contrary. We can hope that none of the medical professionals who go to the plague zone encounter a different strain that has an altered cycle of infectivity. Had some of the previous professionals encountered such a strain, the effects might have been catastrophic.

The United States continues to break things and kill people in the Middle East without a discernible objective other than trying to stave off disasters. We send our air power where the enemy chooses. Allowing the other side to issue marching orders to your soldiers has not been a winning strategy since Demosthenes warned the Athenians against it in one of the Philippics.

So you, if you hear of Philip in the Chersonese, vote an expedition there; if at Thermopylae, you vote one there; if somewhere else, you still keep pace with him to and fro. You take your marching orders from him; you have never framed any plan of campaign for yourselves, never foreseen any event, until you learn that something has happened or is happening.

Demosthenes.

There are a few voices raised in favor of building a US Air Base in Kurdish Iraq. I think I first suggested this a year ago, and it still seems like a good idea. The whole thing proceeds slowly http://www.presstv.ir/detail/2014/10/23/383335/us-to-take-iraq-airport-as-military-base/ and half heartedly, but then the President is very reluctant to commit more forces to Iraq, particularly before the election.

ISIL AKA The Caliphate is our enemy, but is also the enemy of several of our enemies. The destruction of the Caliphate is not possible without a greater commitment of forces than any American administration including a Republican one is likely to send; but securing Iraqi Kurdistan can be accomplished with tactical air power and a brigade of ground forces. Moreover, the same forces could keep Baghdad from falling to the Caliphate, and while the tactical air elements would have to remain American, a good part of the ground element could be created from existing Kurdish forces with US equipment and training. Indeed we might even recapture some of the American equipment given to the Baghdad regime and thrown down in terror for ISIL to pick up and use…

Two major events in space development: the failure and destruction by range safety of an Orbital Sciences rocket carrying supplies and experiments to the International Space Station, and the destruction of the Virgin Airlines SpaceShip Two in the Mohave Desert. The most significant of these was clearly the SS-2 which was destroyed in mid-air.

SpaceShipTwo (SS2), the plane on which the Virgin boss Sir Richard Branson has pinned his hopes of sending commercial passengers to the edge of space at a cost of $250,000 (£156,000) each, broke up during a test flight at about 45,000ft on Friday. The pilot, Peter Siebold 43, managed to parachute to the ground and was described as alert though with serious injuries; the co-pilot, Michael Alsbury, 39, was killed.

http://www.theguardian.com/science/2014/nov/02/virgin-galactic-spaceshiptwo-crash-investigators-fuel-warnings

In actuality, the SS-2 loss, though both spectacular and tragic, was the less significant in all ways other than public perception. The Virgin Galactic space tourism venture is important to commercial space development because it is a path to making money in space, and such commercial activities are needed so that private space investments will continue. If there’s no clear way to make a profit, few people will invest in space activities. A number of people have invested a great part of their lives in trying to develop such activities, and they are to be commended; but space won’t be conquered by heroes and heroines alone. It also takes money and a lot of it.

The Virgin Galactic route to space begins and ends with tourism: going to space, spending a little time there, and coming home. The SS-2 and its successors are airlaunched at 30,000 feet and rocket to space – however high we define “space” to begin – then fall like a badminton shuttlecock into the atmosphere and glide down to a landing. There is no path from this performance to actual spacefaring. Even if SS-2 reaches 100 miles altitude – Low Earth Orbit altitude – it hasn’t “gone orbital” nor could it ever. It’s actual velocity when it reaches maximum altitude is effectively zero, and it falls into the thickening atmosphere at subsonic speeds. This is not “reentry” as an orbital or sub-orbital craft would experience it. The thermal protection problems are not the same, nor are the control and stability problems.

Moreover the hybrid motors of SS-1 and SS-2 could never be built large enough to give the craft appreciable velocity. It can never go orbital.

These craft can make money from space tourism. One can hope the income stream will continue long enough to make the ventures profitable. But they don’t lead to becoming a spacefaring nation.

I have for some years been dubious about the safety of the hybrid engines. I first encountered them when I accompanied the late George Koopman out to his American Rocket Company test site at Edwards for a test firing. The system chugged. Hybrid engines consist of a cast solid fuel block into which an oxidizer is introduced. The fuel is exceptionally safe and stable. It won’t blow in manufacture or storage. If it catches fire it burns. It’s only in a confined place with a powerful oxidant that it becomes rocket fuel. There is a lot to recommend them, including the elimination of fuels tanks and pumps.  The oxidant needs to be supplied from tanks, but not the fuel which burns in place.

The problem with hybrid engines is that the burning takes place on the surface of the fuel. If a piece of the fuel breaks loose from the rest, it burns all over, producing a sudden temporary increase in pressure. If this happens several times it is called chugging, and it makes the flight difficult to control. Something of this sort happened during the X-Prize flights conducted by Scaled Technology.  The hybrid engines won the X-prize, but it was close in the second flight.

If a large enough piece breaks off it can block the flow of rocket exhaust out of the combustion chamber. Pressure rises, and with luck blows the errant fuel chunk out the back and; but if the chunk is too large, the overpressure in the combustion chamber can get too high, rupturing the chamber. Or the pressure can force the propellant to crack, exposing more surface area to the oxidant; more fuel burns. There are other scenarios leading to from mild to catastrophic damage to the spaceplane’s structure.

In my judgment this is likely what happened to SS-2.

http://www.theguardian.com/science/2014/nov/02/virgin-galactic-spaceshiptwo-crash-investigators-fuel-warnings

Note that I have long been critical of the hybrid engine concept. There are other views.

http://online.wsj.com/articles/virgin-galactic-crash-probe-focuses-on-possible-structural-failure-1414972644

[1100 Monday 3 November update: there is considerable evidence that the SS2 was brought down by a flight control problem, not any failure of the engine.]

I would think this is not the end of Virgin Galactic. Sir Richard Branson is a determined man of great courage. It is not the end of man in space, or of commercial space. But it will be used as ammunition for those who want to put all control of such activities in the hands of a bureaucracy.

We lost Grissom, White, and Chaffee and continued. The star road takes its toll.

http://www.jerrypournelle.com/images/phoenix.mp3

[2300 Sunday 2 November]: I am reluctant to get involved in breaking news for the obvious reason that one ends up commenting on stuff only to discover that it isn’t relevant.  My dislike of hybrid engines may well have led me to say more about their problems than is warranted by this incident: I am now getting the story that there may have been control error involved in this.  The feathering system for use in the vertical reentry to the atmosphere may have been activated while the ship was under rocket power.  This would far overstress the structure of the craft, so that it literally tore itself apart. There appears to be some evidence of this found in the wreckage; but again this is speculation in the absence of important information.  I am reluctant to report rumors.

The cause of the crash of SS2 is not yet determined.

 

 

Freedom is not free. Free men are not equal. Equal men are not free.