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From earlier in this thread:
A Density comparison between chalk and Shuttle Orbiter tiles.

Chalk 156 lb/ft3 typically (varies from ~ 112 to 168 lb/ft3)

Shuttle Orbiter tiles:

LI-900 (black tiles on underside) 9 lb/ft3
LI-2200 (black higher strength around windows & landing gear doors) 22 lb/ft3

FRCI-12 (improved tiles to replace some LI tiles) 12 lb/ft3

LRSI-9  (white tiles on upper surfaces) 9 lb/ft3
LRSI-12 (white tiles on upper surfaces) 12 lb/ft3

BRI-18 (strongest & toughest tile produced, replacement for critical areas)  18 lb/ft3

Water 62.4 lb/ft3
Styrofoam packaging and insulation typically 1 to 2 lb/ft3

Conversion to metric:

1 lb/ft3 is equivalent to 0.016 g/cm3 or 16.0 kg/m3
Firefly Aerospace press release:

Firefly Aerospace Successfully Reaches Orbit and Deploys Customer Payloads with its Alpha Rocket

Quote from: Firefly Aerospace
Alpha becomes the first and only orbit-ready US rocket in the 1300kg payload vehicle class

CEDAR PARK, Texas – October 3, 2022 – Firefly Aerospace, a new space leader in launch, spacecraft, and in-space services, announced that its Alpha FLTA002 mission successfully reached orbit and deployed customer payloads, lifting off on October 1 at 12:01am PST from Vandenberg Space Force Base in California. 

With the success of this mission, Firefly is now the first company to launch and reach orbit from US soil in only its second attempt. Firefly also becomes the first and only US commercial space company with a rocket ready to take customers to space in the highly desired 1300kg payload lift class. 

“With the success of this flight, Firefly has announced to the world there is a new orbital launch vehicle, available today, with a capacity that is pivotal to our commercial and government customers,” said Bill Weber, Firefly CEO. “Proving our flight and deployment capabilities on only our second attempt is a testament to the maturity of our technology and the expertise of our team. This is an exciting day at Firefly, and we have many, many more ahead. I could not be more excited for the Firefly team.”

Alpha is an all-composite rocket that uses patented tap-off engine cycle technology, which reduces cost and improves efficiency while maintaining the strength and reliability of the rocket. During the mission, Alpha successfully completed all major technical milestones, including a two-burn maneuver, relighting the second stage during its first orbital flight.

“I am so proud of everyone in the company, both past and present, who have shared my dream of starting a launch company that would further revolutionize the space economy,” said Tom Markusic, Firefly Founder and Chief Technology Advisor. “The Firefly team set out to develop the best small launch vehicle in the world. Mission accomplished!”

Building on today’s success, Firefly is completing the Acceptance Testing Protocol (ATP) for its  Alpha 3 vehicle in preparation for its upcoming NASA VCLS Demo 2-FB ELaNa 43 launch. In addition, Firefly continues the production of multiple rockets at its Texas manufacturing facilities using all the lessons learned from existing flights and testing. Firefly is scheduled for six Alpha launches to take customer payloads to space in 2023, and 12 more in 2024.

Alpha FLTA002 Mission Details

The flight began with a nominal countdown and lift-off at 12:01 AM PDT and progressed flawlessly through each stage of flight, then inserting into an elliptical transfer orbit, coasting to apogee, and performing a circularization burn with confirmation of final payload deployment at approximately T+1 hour, which is one of the most technically challenging aspects of the mission.

FLTA002 deployed a total of three payloads, including demonstration satellites from NASA TechEdSat-15 in conjunction with San Jose State University (SJSU), Teachers in Space, and Libre Space Foundation. These payloads will perform several in-space experiments, including an “exo-brake” to help in the deorbiting of satellites and test the world’s first fully-free and open-source telecommunications constellation.

Firefly sends special thanks to SLD-30 for their continued support and partnership and the customers on FLTA002 for their dedication and unwavering confidence in Firefly’s technology.

Firefly is a portfolio company of AE Industrial Partners, LP (“AEI”), a private equity firm specializing in aerospace, defense & government services, space, power & utility services, and specialty industrial markets.

About Firefly Aerospace

Firefly Aerospace is an emerging end-to-end space transportation company focused on developing a family of launch vehicles, in-space vehicles, and services to provide industry-leading affordability, convenience, and reliability to its government and commercial customers. Firefly’s launch vehicles, combined with their in-space vehicles, such as the Space Utility Vehicle (SUV) and Blue Ghost Lunar Lander, provide the space industry with a single source for missions from LEO to the surface of the Moon and beyond.

About AE Industrial Partners

AE Industrial Partners is a private equity firm specializing in aerospace, defense & government services, space, power & utility services, and specialty industrial markets. AE Industrial Partners invests in market-leading companies that can benefit from its deep industry knowledge, operating experience, and relationships throughout its target markets. AE Industrial Partners is a signatory to the United Nations Principles for Responsible Investment and the ILPA Diversity in Action initiative. Learn more at

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Rocket Lab / Re: Neutron vs F9R and SS
« Last post by john smith 19 on Today at 11:20 am »
The core premise that avionics are too expensive and purely open-loop guidance would be an acceptable alternative may have been true a few decades ago, for fixed-nozzle solid stages.
But today, for a liquid propellant stage, the sensors required are not of extreme cost - particularly as you still need the rest of the avionics suite for open-loop control, engine management, TVC, and other stage functions such as spinup, spindown, and seperation - and even if you decide that ring-laser gyros are too pricey, then your fallback is not 'no IMUs' but use of MEMS IMUs.

You're giving yourself a lot of new headaches, making your vehicle less reliable (the first stage now needs to perform absolutely perfectly as your upper stage has no capability to compensate), for a very tiny cost saving.
You might like to read what I wrote again. Slowly.  :(

Sensors are not a problem. If they come from established mass market products.
 Specialised sensors, such as IMU's that update fast enough to deal with orbital speeds are expensive and have to be thrown away.
Specialised actuators like the kind to gimbal a whole rocket engine (and the gimbals themselves) are also an issue.
Again it's about the economics of making the expendable components as cheap as possible, because you have to make them for every launch. If the baseline S2 can deliver the necessary accuracy without them then that's a clear win.  Photon would then be available if super-tight orbital parameters or additional delta v are needed.

You'll notice I called out 2 specific areas. IMU's and TVC. Those are the most specialized and highest power elements. They are expensive to make and every expendable stage (unless they are designed out) has to have a new set of them.

If you've got the luxury of a clean-sheet design (as RL have) it makes sense to look at all ways to lower recurring costs. The cheapest, lightest and most reliable parts are the ones the design does not include to begin with.

Time will tell how RL approach this question.
Ok, since no reaction is apparent, from


LAUNCHED: 3337 (NOT 3347, which is WRONG) if only v1 satellites are considered. Otherwise, +60 when counting v0.9 (total = 3397).

DEFINITELY REENTERED: 212 (NOT 228, which is WRONG) if only v1 satellites are considered. Otherwise, when counting v0.9, +58 should be added (total = 272).

REENTERING: Best estimate is 44, although some of these may turn out to be salvageable. This brings the total of non-working S/C to 256 (or 258 if counting v0.9s, since two remain in orbit but are close to reentry), correspondingly leaving around 3081 S/C operational at some level, exclusively v1.
That yields an "out-of-operation" rate between 6.4% and 10.3%, depending on what v0.9s are counted as.


There are around 16 S/C under active disposal from an operational orbit (not the low-altitude injection one), and other 16 in apparently anomalous situations, bringing the total of fully operational satellites to 3042, for a "fully operational" rate between 89.6% and 91.2%, again depending on what you count v0.9s as.

A small number of these may be in reserve, but there are currently many more (estimated at over 400) either drifting or ascending to their operational slots, leaving around 2600 of in-service S/C.
Chinese Launchers / Re: Tiangong - Chinese Space Station
« Last post by Rondaz on Today at 11:15 am »
Harvest in space. Planting and more experiments conducted by astronauts in Tiangong Space Station (CSS).

Orbital Launch no. 128 of 2022

SES-20 | ULA | Oct 04 | 2136 UTC

@ULA to launch 2 Geostationary comm🛰️ #SES20 & #SES21 - enhancing 5G & digital telecommunications in North America - on top of its #AtlasV [531 config] from SLC-41 @SLDelta45,  Cape Canaveral, Florida.
Orbital Launch no. 129 of 2022

Crew 5 | SpaceX | Oct 05 | 1600 UTC

@NASA & @SpaceX to launch #Crew5 mission to @Space_Station. Crew: 🇺🇸Cmdr @AstroDuke & pilot @astro_josh, @Astro_Wakata
& 🇷🇺Anna Kikina. #USCV5 mission is 8th crewed mission for SpaceX!
Orbital Launch no. 127 of 2022

Starlink L62 | SpaceX | Oct 03 | 2321 UTC

@SpaceX to launch another batch of 52 #Starlink V1.5🛰️ (G4-29) on its #Falcon9 FT (booster #B1071.5) from pad SLC-4E, @SLDelta30, California.
Something Quite Different 10/3/2022

Version 2.0 of the @SpaceX #Starlink tracker/simulator now released on - major new feature is the capacity simulator.
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