Pegasus Launch Timeline

[ascan1984]

http://www.spaceflightnow.com/pegasus/galex/030424ascenttimeline.html <br /><br />T+00:00 Drop <br />The Pegasus XL rocket is released from the Orbital Carrier Aircraft off the east coast of Florida at an altitude of 39,000 feet above the Atlantic Ocean. <br /> <br />T+00:05 Ignition <br />The first stage solid-fueled motor of Pegasus is ignited to begin the powered journey to orbit with GALEX. <br /> <br />T+01:15 Stage 1 Burnout <br />The Orion 50S XL first stage motor consumes all of its solid-fuel propellant and burns out. A short ballistic coast period begins now. <br /> <br />T+01:31 Stage 1 and 2 Separation <br />The spent first stage motor is jettisoned to prepare for the second stage of flight. The first stage casing falls into the Atlantic Ocean. <br /> <br />T+01:31 Stage 2 Ignition <br />The Pegasus rocket's Orion 50 XL second stage begins firing to continue the trip to orbit. <br /> <br />T+02:06 Jettison Payload Fairing <br />The payload fairing that protected the GALEX satellite during atmospheric ascent is separated once heating levels drop to predetermined limits. <br /> <br />T+02:44 Stage 2 Burnout <br />Having consumed its supply of solid-fuel propellant, the second stage motor burns out. A coast period now begins before releasing the spent stage. <br /> <br />T+07:41 Stage 2 and 3 Separation <br />With its job complete, the Pegasus rocket's second stage is jettisoned from the third stage. <br /> <br />T+07:52 Stage 3 Ignition <br />The solid-fueled Orion 38 third stage ignites to deliver the GALEX spacecraft into the desired orbit around Earth. <br /> <br />T+09:00 Stage 3 Burnout <br />The third stage burns out after using all its solid propellant, completing the powered phase of launch. Orbit insertion has now occurred. <br /> <br />T+11:00 Spacecraft Separation <br />NASA's Galaxy Evolution Explorer spacecraft, or GALEX, is released into space from the third stage to complete th

 

[mikejz]

I really wonder what the fate of Pegasus once/if the SpaceX Falcon comes online.

 

[CalliArcale]

It'll carry on. I expect there will be sufficient payloads to keep flying it, especially as it has such a good track record. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[strandedonearth]

I wonder if a Pegasus could be launched from the White Knight carrier aircraft...?<br />

 

[nacnud]

You really think it will keep flying even if the competion is a third the price? Assuming similar reliablity that is.

 

[CalliArcale]

I'm inclined to doubt that the competition really will be a third the price in practise and still have similar reliability. <img src="/images/icons/wink.gif" /><br /><br />Also, there's the factor that Pegasus is mobile, and that you can book rockets right now with a high degree of confidence. It will take Falcon a while to acheive the same degree of customer confidence. Which will win then? Depends on whether Falcon can deliver on its cost promises, whether they can supply enough launches to meet demand, and whether it does acheive similar reliability. Sooner or later, Pegasus (like all rockets) will make its last flight. Odds are, Orbital will have a new vehicle by then. The only way to tell which rocket will have the larger market share will be to wait.<br /><br />Of course, by then Orbital may have found a way to decrease prices to remain competitive. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>I wonder if a Pegasus could be launched from the White Knight carrier aircraft...? <p><hr /></p></p></blockquote><br /><br />Well, White Knight is already carrying the X-37 prototype for drop tests. That should give us some good figures for comparison. Interestingly, X-37 was originally slated for B-52 drop tests, and B-52s have also carried the Pegasus rocket.<br /><br />The X-37 Approach and Landing Test Vehicle has a mass of 3700 kg, according to astronautix.com, and its dimensions are approximately 8.38m x 4.57m. Pegasus, according to the same souce, has a mass of 19,000 kg. So either X-37 is way under White Knight's capabilities, or it can't carry Pegasus. The obvious next thing to check is SpaceShipOne. That's got a mass slightly less than X-37 ALTV: 3600 kg.<br /><br />I was unable to find actual figures for White Knight's capabilities, but it doesn't look encouraging from this. It's just not big enough. Additionally, it would be unable to support some of the features of the Stargazer (a modified Lockheed Tristar airliner), which provides an umbillical to the payload for data and coolant up to moments before release. But I'm sure Rutan could come up with something. <img src="/images/icons/wink.gif" /> White Knight will have a successor to carry the much more massive SpaceShipTwo, and that may well be large enough. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mikejz]

I Wonder how much of a Pegasus's costs are the ATK solid fuel motors, and if the Falcon were to prove to be a viable competior, if Orbital might be able to get ATK to substaintally cut the cost of it's motors?

 

[ve7rkt]

If we go by the specs on astronautix, and assume that the entire difference between full and empty weight on each stage is fuel, there's 16032kg of propellant in a Pegasus H.<br /><br />If I were certified higher, I could buy a big honkin' model rocket motor reload, the Cesaroni 98mm N2500, a 6.8kg slug of APCP -- similar fuel to the Shuttle's SRB's -- costs C$1099.95 at a hobby shop, which is US$942.73 this week. That's US$138.64/kg.<br /><br />At that rate, the fuel in a Pegasus H would cost a little under $2.3 million, or about 1/5 the cost of the whole mission.<br /><br />Of course, that's consumer grade, hobby shop, licensed and certified and insured against some dipswitch screwing around with cardboard tubes pricing. Wild guess: the motors are actually a whole lot cheaper than that, so they make up even less of the cost of a launch. So reducing the cost of the motors isn't going to affect the launch price much.