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SpaceX performed a hold-down test-firing of the Falcon 9’s first stage Merlin engines Friday. The test-firing is a customary pre-launch checkout before every SpaceX mission, providing a test of launch vehicle systems and a rehearsal for the company’s launch team.
The Falcon 9 was raised vertical at pad 40 without its satellite payload or fairing Friday in preparation for the static fire test. SpaceX loaded super-chilled, densified kerosene and liquid oxygen propellants into the two-stage Falcon 9 rocket, and the countdown proceeded through through the final steps before launch, including retraction of the strongback structure into position for liftoff and pressurization of the rocket’s propellant tanks. //
The nine Merlin 1D engines at the bottom of the Falcon 9’s first stage ignited for several seconds at 1:20 p.m. EST (1820 GMT) Friday, throttling up to full power to generate some 1.7 million pounds of thrust as hold-down restraints keep the rocket firmly on the ground.
SpaceX engineers will perform a data review after the static fire as technicians at Cape Canaveral roll the rocket back to the hangar and prepare to mate it with the JCSAT 18/Kacific 1 communications satellite inside a climate-controller hangar.//
The Falcon 9 rocket slated to launch the JCSAT 18/Kacific 1 spacecraft is a veteran of two previous missions. It first launched in May on a space station cargo mission, then landed on SpaceX’s drone ship in the Atlantic Ocean. On its second flight, the rocket again powered a Dragon supply ship toward the space station, and returned to Cape Canaveral for an onshore landing.
SpaceX is expected to recover the first stage again after Monday’s launch aboard a drone ship in the Atlantic east of Florida’s Space Coast.
The 15,335-pound (6,956-kilogram) JCSAT 18/Kacific 1 spacecraft will launch into an elliptical transfer orbit, then use its on-board liquid-fueled engine to maneuver into a circular geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator.
Arianespace has reached some notable milestones (or soon will).
Iterative design is faster and arguably better. But you have to be willing to fail. //
This "fail early, fail forward" strategy allows a company to move more quickly and improve its design along the way. It also results in public failures, such as the all-explodey rocket Wednesday. //
For casual observers of spaceflight, this "iterative" design philosophy is very different from the much slower, linear design process used by traditional aerospace partners for large development projects. Under this more traditional process, a company—or, historically, NASA—seeks to avoid the risk of a rocket failing before it is perfected. Years are spent designing and testing every component of a vehicle before it is assembled for a full-scale test. As a result the process is much slower and more costly. //
It is easier for a company like SpaceX working on a self-funded project like Starship to do this than a government agency, noted Phil Metzger, a planetary scientist at the University of Central Florida. "You have to let people see you fail, and you have to push back when the critics use your early failures as an excuse to shut you down," he recently said. "This is why it is hard for national space agencies to adopt it. The geopolitics and domestic politics are brutal." //
MrTeapotSeniorius Lurkiusreplyabout 8 hours agoReader Fav
DanNeely wrote:
It was. OTOH Saturn 1 was highly iterative; with almost every launch prior to the 1b series being a different configuration as they went from a first stage with a mass simulator on top, to a first and second stage with a simulator in place of a payload, to flying a boilerplate Apollo capsule; all while fiddling with the rest of the stack below.
I had the opportunity to hear a bunch of Apollo engineers talk when NASA celebrated 50 years since Explorer 1 was launched. They wanted Saturn V to be iterative to, but to meet schedule, they decided to gamble instead. In general though, all the NASA contractors are highly dependent on simulation and systems integration labs. The perception is that's cheaper than blowing hardware up, but I'm not certain that's true. //
greybeardengineerArs Centurionreplyabout 8 hours agoReader Fav
VidasDuday wrote:
Fail fast. Fail often. Succeed sooner.
Edit: As I recall, the Saturn V stack was also a combined unit and integration test- smoke or blow.
The Saturn V stages were also tested individually. And sometime didn't pass.
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Trevor Mahlmann
is creating lighthouse, landscape, and rocket photography.
This is a video of every SpaceX landing or landing attempt of which a video was taken. I tried to edit it down as much as possible but it still ended up pretty long, mainly due to including Grasshopper and F9R flights (I didn't feel I could use the word "every" if I didn't). I made this because I couldn't find any such compilations on Youtube. Most videos are from SpaceX's Youtube Channel. Thanks for watching and thanks to SpaceX for all the excitement.
Here is the full list of all launches that I used as my notes while putting this together:
The Catalog
I have compiled a catalog of over 1000 artificial objects in `deep space'. Version 1.0 of this catalog has been released online at https://planet4589.org/space/deepcat.
By deep space, I mean broadly space beyond the region where the US satellite catalog provides coverage. Note that the term has been used with a variety of definitions. In the context of the SGP4 orbit model [3], deep space' refers to orbital periods above 225 minutes, corresponding to altitudes of about 5900 km, a region normally thought of as
medium Earth orbit' these days. For our purposes a boundary somewhere beyond 50,000 km seems needed. It also appears desirable to exclude communications satellites on supersynchronous transfer orbits which have apogees typically in the 60,000 to 100,000 km range.
For definiteness I adopt a boundary I call [14] EL1:4, the Earth-lunar 1 to 4 orbit resonance in which a satellite in a circular orbit will complete four revolutions of the Earth for every one that the Moon does. EL1:4 is at 152066 km from Earth's center. The choice is motivated by the idea that satellites well within this distance can to first order ignore the Moon and be regarded as being in simple Keplerian orbits on short timescales (clearly, even much closer in at GEO, lunisolar perturbations are important on longer timescales). Satellites at this distance or beyond are more strongly affected by lunar perturbations and should be considered as part of a three-body system. This distinction is obviously not a sharp one and is somewhat arbitrary but it seems as good as any. It also echoes the Sun-Jupiter 1 to 4 resonance which approximately marks the inner edge of the asteroid belt and which serves as a good candidate for a boundary between the inner and outer solar system.
Space situational awareness (SSA), for all its challenges, is relatively mature in LEO and GEO. In comparison, the situation beyond GEO is chaotic. No organization is charged with maintaining SSA for deep space objects either in distant Earth orbit or beyond Earth orbit. There is no formal interface between the astronomers who accidentally detect deep space objects while searching for asteroids and the astronautics community. Organizations such as JPL keep track of their own active probes but not of their discarded rocket stages nor the probes of other nations. This situation has been tenable due to the low flight rate of deep space missions to date, but that is changing with the arrival of commercial lunar missions and deep space cubesats, and the increasing number of states carrying out deep space exploration. I present a historical database of about 1000 deep space objects and argue that the time has come to plan for internationally coordinated deep space traffic management.
Get yourself a heat shield, and throw the parcel really hard—backward. //
The Earth’s atmosphere weighs as much as a layer of water 10 meters thick. To figure out whether a meteor is likely to make it through, you can imagine that it’s literally hitting a 10-meter layer of water. If the object weighs more than the water it would have to push aside to reach the surface, it will probably make it through. This works pretty well for a rough approximation!
At one point in time, the United Launch Alliance (ULA) - infamous for partially enforcing a monopoly over US launch markets and relying on old but proven technology - was actively pursuing advanced tech that could eventually enable orbital propellant depots and create what was described as a "cislunar economy".
Led in large part by former Vice President of Advanced Programs George Sowers (2006-2012, 2015-2017), ULA has pursued orbital refueling and propellant depots for the better part of a decade. //
Apparently, after he began a renewed push for propellant depots and reusable upper stages in 2015, Boeing quite literally tried to have him fired, clearly taking the depot concept as a direct threat to a big slice of pork: NASA's Space Launch System (SLS) Core Stage (booster) contract. //
"Senator [Richard] Shelby [R - AL] called NASA and said if he hears one more word about propellant depots, he’s going to cancel [NASA's] space technology program." //
NASA has spent more than $2B annually on SLS alone in FYs 2017, 2018, and 2019, accounting - as of October 2019 - for nearly $6.5B spent on SLS in the last three years alone. SLS funding is likely to be increased yet again by Congress in FY2020. Since the Constellation Program's (2005-2010) Ares V rocket was rebirthed as the SLS program in 2011, NASA has spent more than $16B on the rocket alone, while its launch debut has slipped more than 4 years (late 2017 to late 2021). //
Whatever the end result, Sowers' blunt description of how Boeing (and SLS) have stunted US spaceflight innovation for years is simultaneously depressing and unsurprising, but serves as an extremely rare instance of candor from a former executive of a traditional US aerospace company.
Merlin 1D and MVacD both rely on a relatively simple, reliable, cheap, and easy method of chemical ignition, using a duo of pyrophoric materials known as triethylaluminum-triethylborane (TEA-TEB). When mixed, these materials immediately combust, generating an iconic green flash visible during Falcon 9 and Heavy launches, and thus producing the ‘spark’ needed to start Merlin engines.
Generally speaking, TEA-TEB is an excellent method of igniting rockets, even if it is more of a brute-force, inelegant solution than alternatives. It does, however, bring limitations: every single ignition requires a new ‘cartridge’ be expended, fundamentally limiting the number of times Merlin 1D (and Merlin Vacuum) engines can be ignited before and after liftoff.
This doesn’t even consider the fact that TEA-TEB are extremely complex chemical products that would be next to impossible to produce off of Earth, at least for the indefinite future.
To combat these downsides, SpaceX has designed Raptor with an entirely different method of ignition, known as torch ignition. Technically speaking, Raptor’s power, design, and methalox propellant combine to demand more than a relatively common solution, in which spark plugs are used to ignite an engine. Instead, Raptor uses those spark plugs to ignite its ignition sources, what CEO Elon Musk has described as full-up blow torches. Once ignited, those blow torches – likely miniature rocket engines using the same methane and oxygen fuel as Raptor – then ignite the engine’s methane and oxygen preburners before finally igniting those mixed, high-pressure gases in the combustion chamber. //
the fact that Raptor is a full-flow staged-combustion (FFSC) engine means that the pressures it must operate under are extreme, verging on unprecedented in large-scale rocketry. Extremely high-pressure gases (on the order of 3,000-10,000+ psi or 200-700+ bar) are just as difficult to reliably ignite, especially if hypergolic solutions (i.e. TEA-TEB) are off the table.
Like, seriously. //
On Thursday morning, United Launch Alliance's Delta IV Medium rocket took flight for the final time. //
Since 2002, this rocket (which can fly with or without small, side-mounted solid rocket boosters) has flown 29 missions. All have been successful. //
But the venerable Delta rocket will fly no more. Put simply, in today's marketplace—in which United Launch Alliance must compete with SpaceX for national security launches and with many other providers for commercial missions—the Delta-IV Medium cannot compete.
A 2017 report by the US Government Accountability Office put the per-unit cost of a single-core Delta launch at $164 million. This is nearly three times the price of SpaceX's Falcon 9 rocket, which can not only be re-used but has comparable or better performance. //
To compete more effectively in this new landscape, United Launch Alliance is phasing out its use of heritage Delta and Atlas rockets in favor of a new Vulcan-Centaur rocket. In dropping the Delta IV Medium, the company is eschewing Aerojet Rocketdyne's costly RS-68A main engine in favor of the less-expensive BE-4 engine under development by the new space company Blue Origin. Similarly, it is seeking to cut costs on Vulcan in other ways, while maintaining its performance.
The immediate thought that would probably come into your mind would be "Because 4 legs is more stable than 3." However that is not always true. 3 legs offer the same or in some cases more stability...
Although alternatives such as SpaceX’s Falcon Heavy exist, the space agency is legally required to launch its Europa Clipper spacecraft on the behind-schedule Space Launch System //
The current appropriations bill mandates Europa Clipper use the SLS and requires a “launch no later than 2023” on the rocket. //
Each SLS launch is estimated to run more than $1 billion. //
2025—or on something other than the SLS—it would be in violation of current law, which means the law must change or a working SLS must suddenly appear in order for Europa Clipper to take off in accordance with federal statute. //
The SLS has an undeniable advantage over Falcon Heavy: it enables a direct flight from Earth to Jupiter. Falcon Heavy will require gravity assists from other planets, and unless it uses an add-on “kicker stage”—an additional upper stage for extra loft—one of those gravity assists will require an encounter with Venus. According to Salute, a Venus flyby introduces “a riskier environment, radiation and temperature. And so we would like to avoid flying closer to Venus with this direct trajectory that SLS affords us.
Ben Blackburn says:
August 5, 2019 at 3:34 pm
Airlines land, refuel and take off all the time, and all the pilots do is walk around and kick the tires between flights. That is the goal for Starship.
Yes, they will inspect any heat shielding that it has after every flight, but it will be designed so that it doesn’t take months to inspect like the Shuttle,, and won’t need repair under normal circumstances.
The shuttle used an aluminum skin and structure, so any heat leakage would cause catastrophic failure because the aluminum just falls apart..Starship will be stainless steel, so it may warp or melt in worst case scenario, but only where the damage is, and they won’t have crew or fuel directly on the other side. So much more robust design, and being a simple shape, much less complicated heat shielding design.
The Starship booster is about the same diameter as the Shuttle external tank, and about 50 feet longer.
It will have more fuel, and more power, than the shuttle did.
And then Starship will be sitting on top of it, instead of on the side like the shuttle.
And unlike the shuttle, Starship has a lot of fuel on board itself.
The shuttle only used fuel from the external tank and had none on board.
So when you look at the total fuel on board the full stack its considerably more than shuttle had.
This is possible because the Raptor engines are more powerful and efficient with the ffsc design.
As far as fuel for landing, it will take very little fuel for the booster to land, because most of its weight will be gone as fuel is burned on ascent so it just needs enough to run 1 or 3 out of the 31 engines and only for a few seconds.
Ben Blackburn says:
August 5, 2019 at 3:12 pm
The check valves were needed to prevent propellant from going from the propellant tanks back into the unpressurized helium lines.
There is a valve at the helium tank, long pipes taking a twisted path to the propellant tanks, a check valve at the propellant tanks, and then throttle valves between the propellant tanks and the engines.
Once the helium valve is turned on, the pressurization lines are at a higher pressure than the propellant, so no propellant will get back up into the helium lines.
And once the system is activated and pressurized, it will stay pressurized until it lands and is safed, either for abort or for propulsive landing.
The throttle valve is what controls the engines for maneuvering, the fuel system stays pressurized.
In order for propellant to mix, it would have to travel upstream a long distance through 2 long and twisty pipes, and then back feed through 2 pressure regulator valves, and finally to the manifold at the helium tank.
That’s not going to happen!
What did happen is that a small amount flowed back through a check valve and pooled in a low spot in the piping, and then when the system was pressurized rapidly, it was driven at extreme force down the pipe, like water hammer burst the check valve, and under the high pressure and temperature of the impact reacted with the titanium in the valve causing the explosion. It wasn’t propellants mixing that caused it, and as long as the system is pressurized, the helium prevents the back flow.
SpaceX is irrevocably on a path to a much larger craft called “BFR” or the more family-friendly “Starship”. This is intended to have all of the features that Falcon and Dragon are not getting. They developed a staged-combustion full-flow engine to fly it. This is more powerful than other engines, and around twice as complicated, as there is a fuel-rich and an oxidizer-rich pre-combustion stage, each with its own turbopump. This recently flew on the hopper prototype in Boca Chica, Texas. However, it avoids pumping fuel and oxidizer on the same shaft, as all conventional liquid-fueled rockets do today, which requires a lot of the seal between them.
This was the first flight of that sort of engine not to end in explosion since 1969, when the Russian N1, their answer to the Saturn V, failed 23 seconds after lift-off, causing one of the largest non-nuclear explosions in history.
Despite this entire project looking far-fetched and being carried out in an unconventional way (construction of major components outdoors, a low-fidelity prototype that could have been a water tower, but flew), they have made tremendous progress. SpaceX and Musk make very ambitious bets, and carry them out, which appears to have been missing from other space efforts.
I understated. It was the first flight of that engine type ever which did not end in explosion. I think only three design attempts have even made it to a test stand.
When the SpaceX Dragon spacecraft reached orbit for the first time in 2010, it was a historic achievement. But to qualify for NASA’s Commercial Orbital Transportation Services (COTS) program,… //
Unfortunately, this complex dual-function system has now become something of a liability. SpaceX believes the explosion in April was not due to a fault in the SuperDraco engines themselves, but in a leaky one-way check valve. Put simply, the propellants leaked into a part of the system in which they were never designed to be. When the propellant tanks were pressurized in preparation of firing the engines, the foreign liquids caused the plumbing to rupture. The resulting release of the highly energetic hypergolic hydrazine and nitrogen tetroxide propellants used in the SuperDraco tore the spacecraft to pieces almost instantaneously. //
Replacing the valves with single-use burst discs means the SuperDraco engines cannot be fired until they are actually needed, and when they are activated, they’ll likely be run until the propellant tanks are dry. In short, the switch to burst discs means the SuperDraco engines are much closer to the traditional “one and done” abort systems than SpaceX originally envisioned.
Technology, People, Equipment, Missions
Here's how they did it.
The heart of the engine was the thrust chamber, which mixed and burned the fuel and oxidizer to produce thrust. A domed chamber at the top of the engine supplied liquid oxygen to the injectors, which directed fuel and oxidizer into the thrust chamber for mixing and combustion. An incredibly volatile chamber that had to be tested to perfection. While the Apollo 6 launch was a bit shaky, when they launched the rocket again with its first human crew on Apollo 8, they had fixed the pogo problem.The crew of three made it safely to the moon and back. By the time Apollo 11 launched to the moon in July of 1969, the Saturn V was flying smoothly. During the remaining Apollo missions and subsequent launches the Saturn V and F-1 engines never experienced a failure. It was perfect, and the F-1 engine still holds the record as the largest single-chamber, single-nozzle liquid fuel engine ever flown.As NASA looks to manned missions to the moon and mars, they are developing a new rocket called Space Launch System (SLS). It will require a modern version of the F-1 and NASA engineers have even pulled an old F-1 engine out of storage to learn how to build the next big thing even better by studying this incredible engine with a perfect flying record.