Raumfahrt - SpaceX will use a parasail guidance system to land Falcon 9’s fairing into a huge net


SpaceX recovery vessel Mr Steven officially departed Port of Los Angeles on the evening of July 23 and is speeding towards its first Falcon 9 fairing recovery attempt since a major series of refits and upgrades. With massive new arms and usable net area increased fourfold, chances are better than they’ve ever been for the iconic clawboat to at last snag its first true ‘catch’ of a parasailing payload fairing.


Set to be stationed roughly 900 km (600 mi) southwest of the California coast, Mr Steven’s vast new net should dramatically even the playing field, cutting the effective error margin for each fairing catch attempt by as much as 60% on its own. An extra ~30 meters of net both length and width-wise would functionally act as a cushion for the ~50-meter accuracy the fairings have demonstrated thus far (i.e. halves missed Mr Steven’s smaller, original net by 50 m).

Still, the question remains for many people: how exactly does Mr Steven ‘catch’ a clamshell fairing half, and how does that fairing half find its way to Mr Steven?


SpaceX’s fairing catcher Mr Steven prepares to debut his new net and arms to catch a Falcon 9 payload fairing, NET July 25. (Pauline Acalin)



Each Falcon 9 fairing is a two-piece 1600 kg sandwich of carbon fiber composites and aluminum honeycomb, as well as internal dressings of soundproofing panels, cold nitrogen gas thrusters for attitude control in vacuum, and finally the parafoil and control hardware/avionics necessary to safely recover the fragile halves. Stretching 13m long and 5.2m wide (43ft x 17ft), SpaceX has partially worked with contractors already experts in the art of autonomously guiding parasails with payloads up to 10,000 kg (22,000 lb), and doing so with some level of accuracy.

Ultimately, GPS-guided parafoils have been done successfully many times over in the past two or so decades. For the most part, the problems preventing SpaceX from recovering fairings in Mr Steven’s net have been almost entirely solved: the fact that six or more halves have been recovered intact after their Falcon 9 launches confirm that much. SpaceX engineers have somehow found a way to allow a highly flexible, lightweight, and aerodynamically awkward lifting body to survive a journey from heights of 110+ km and speeds of several kilometers per second.


One half of SpaceX’s Iridium-6/GRACE-FO just moments before touchdown on the Pacific Ocean. (SpaceX)


Per the extraordinarily minimalist appearance of each half’s parafoil recovery hardware and the lack of any clear control mechanism, it’s very likely that SpaceX has sided with an in-canopy (canopy=the parachute) system of actuators tasked with subtly warping the parafoil, comparable in functionality to a crude replica of a bird’s wing.


Birds fly with such extraordinary precision thanks to granular control surfaces known by most as “feathers”, whereby slightly tweaking the location of feathers or changing the shape of the wing can result in a huge range of behaviors. In-wing actuation and control is an elegant – if complex – solution for the problems posed by parafoil guidance. In this case, SpaceX’s contractor (MMIST) likely deserves at least some of the credit for several nearly successful catch attempts thus far, delivering each unpowered fairing half from an altitude of 110+ kilometers, speeds of more than 2 kilometers per second, and parabolic trajectories stretching over 800 kilometers to a square roughly 100m by 100m.

If each halve’s accuracy can be cut by 75% of that to an area of 50m by 50m, SpaceX and Mr Steven should have no trouble in reliably and routinely catching Falcon 9 payload fairings for rapid reusability, perhaps one day translating into a similar approach for the recovery of Falcon 9’s orbital upper stages and SpaceX’s Crew and Cargo Dragon spacecraft. Mr Steven’s new net upgrade is meant to accomplish exactly that by offering a much larger surface area for Falcon fairings to ‘aim’ at.




From left to right, my best guess for each fairing is PAZ, Iridium-6 Half 1, Iridium-5, and Iridium-6 Half 2. (Pauline Acalin)

Once the massive 800-kilogram components can be captured in flight by Mr. Steven, it should be a fairly simple prospect for SpaceX to move from recovery to reuse, potentially saving as much as 10% ($6m) of the cost of each Falcon 9 and Falcon Heavy launch in one simple, fell swoop. Perhaps even more importantly, fairing reuse would remove some of the pressure placed on SpaceX’s composite production floor, which currently must support the fabrication of dozens of fairing halves, booster interstages, payload adapters, Falcon Heavy nose cones, and much more, including smaller subassemblies required for both Crew and Cargo Dragons.

BFR is gonna need all the composite design and manufacturing expertise it can get.

For prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket recovery fleet (including fairing catcher Mr Steven) check out our brand new LaunchPad and LandingZone newsletters!



SpaceX’s fairing-catching boat heads to sea, this time with a bigger net 

SpaceX’s fairing recovery boat, Mr. Steven, will debut a bigger net during Wednesday’s launch f a Falcon 9 rocket from Vandenberg Air Force Base, California. Credit: SpaceX

After several near-misses in tries to catch payload shrouds jettisoned from Falcon 9 rockets climbing into space, a high-speed boat tasked with retrieving the fairings for SpaceX to reuse has been upgraded and dispatched into the Pacific Ocean ahead of a launch Wednesday from Vandenberg Air Force in California.

The fairing retrieval vessel, named “Mr. Steven,” left the Port of Los Angeles late Monday heading for a position in the Pacific Ocean several hundred miles south of Vandenberg, where the two halves of the Falcon 9’s payload fairing will fall after launch with 10 Iridium voice and data relay satellites.

The fairing will split open like a clamshell around three minutes after liftoff, set for 4:39:30 a.m. PDT (7:39:30 a.m. EDT; 1139:30 GMT) from Space Launch Complex 4-East at Vandenberg, a military facility around 140 miles (225 kilometers) northwest of Los Angeles.

Each half of the fairing carries a guidance system, tiny thrusters, and a parafoil to control its descent back to Earth. Instead of having the fairing components plunge into the sea, as happens with other rockets, SpaceX wants to recover the reuse the fairing, following in the footsteps of the company’s accomplishments in recycling the Falcon 9’s first stage booster.

Mr. Steven will attempt to maneuver under one of the fairing halves, aiming to catch the composite structure with a net. A little closer to the California coast, another vessel, a drone ship named “Just Read the Instructions,” will hold position for landing of the Falcon 9’s first stage booster.

It will be the first time SpaceX will use ocean-going vessels to recover both the Falcon 9’s first stage and part of the payload fairing on the same mission. If SpaceX can snag both parts of the rocket Wednesday, it will be the first time the company has retrieved part of the fairing with Mr. Steven, and the 26th first stage booster to successfully land intact.

SpaceX has tried to catch fairings before, but none of them have fallen into Mr. Steven’s net, which engineers have nicknamed the “catcher’s mitt.”

A before-and-after view of Mr. Steven with the old net and the new, larger net. Credit: SpaceX

The payload fairing protects satellites riding into space aboard SpaceX’s Falcon 9 rocket, keeping the spacecraft pristine and shielding satellites from weather conditions during pre-launch preparations, and aerodynamic forces during the launcher’s climb through the dense, lower regions of the atmosphere.

Once in the rarefied, nearly airless environment of space, the Falcon 9 is programmed to jettison the fairing.

So far, SpaceX has only tried to use a boat to catch the fairing during missions launched from Vandenberg, which is used for launches with satellites heading into orbits that fly over Earth’s poles. The company is expected to eventually deploy multiple vessels for fairing recoveries after launches from California and Florida.

Payload fairings from Falcon 9 launches from Cape Canaveral have also carried recovery gear, but SpaceX has not yet attempted a retrieval with a net-outfitted boat in the Atlantic Ocean.

SpaceX acknowledged the existence of Mr. Steven earlier this year, and the ship made its first known attempt to catch a fairing shell on a Feb. 22 launch from Vandenberg with the Spanish Paz radar observation satellite and two testbeds for SpaceX’s planned broadband Internet network.

Part of the payload fairing from a May 22 launch of a Falcon 9 rocket floats in Pacific Ocean. Credit: SpaceX

During SpaceX’s last launch from Vandenberg on May 22, Mr. Steven came within about 50 meters, or 160 feet, of catching one half of the Falcon 9’s payload fairing, the company said on Twitter.

The new net on Mr. Steven is four times the size of the previous one.

“Catching rocket fairings falling from space has proven tricky, so we made the net really big,” SpaceX founder and chief executive Elon Musk wrote in a Twitter post earlier this month.

Ultimately, the fairing reuse initiative should substantially cut launch costs, according Musk.

With the latest upgrades introduced in the Falcon 9 rocket’s “Block 5” version, the Falcon 9’s fairing is “designed for full recoverability,” Musk told reporters in a May 10 conference call.

But engineers want to retrieve the fairing with a ship, rather than allowing the shroud to fall into the sea, where salt water can damage or contaminate sensitive parts.

“In future flights, we’re confident that fairing reuse will be effective, which is a big deal because each one of those fairings cost about $6 million to build, and it represents a significant percentage of the airframe of the rocket,” Musk said.

SpaceX’s Falcon 9 rocket was raised vertical Tuesday at Vandenberg Air Force Base, California, in advance of liftoff early Wednesday. It will be the first Falcon 9 Block 5 model to take off from California. Credit: SpaceX

The satellites riding Wednesday’s Falcon 9 launch will push Iridium’s new-generation “Iridium Next” voice and data relay constellation to near completion.

The Falcon 9 rocket completed a hold-down engine firing at its Vandenberg launch pad Saturday, and ground crews rolled the launcher back into its hangar for attachment of the 10 Iridium Next satellites and their custom-designed multi-payload dispenser.

The fully-assembled rocket was raised vertical at SLC-4E on Tuesday, and the launch team plans to arrive on station in their control center overnight, as the countdown ticks toward a predawn liftoff at 4:39 a.m. local time.

The launcher set for blastoff Wednesday will be the third Falcon 9 rocket to feature an upgraded Block 5 first stage booster, the latest version of SpaceX’s workhouse launch vehicle, and the first Block 5 mission from California.

Wednesday’s mission will come a little more than three days after the most recent Falcon 9 mission, also a Block 5 flight, from Cape Canaveral. A Falcon 9 rocket lifted off from Florida’s Space Coast early Sunday with the Telstar 19 VANTAGE communications satellite, a powerful broadband station heading for a perch in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator.

Built by Thales Alenia Space and Northrop Grumman Innovation Systems — formerly Orbital ATK — the Iridium relay satellites fly in lower orbits, and the Falcon 9 rocket will head south from California’s Central Coast into a polar orbit.

Artist’s concept of an Iridium Next satellite. Credit: Iridium/Thales Alenia Space

The flight plan calls for shutdown of the Falcon 9’s second stage engine at T+plus 8 minutes, 33 seconds, followed by a 43-minute coast phase before restart of the Merlin upper stage powerplant for a nine-second burn starting at T+plus 51 minutes, 33 seconds.

Then the 10 Iridium Next satellites, which each weigh around 1,896 pounds (860 kilograms), will deploy from the upper stage at intervals of every 90 seconds. All 10 spacecraft should be separated from the rocket by T+plus 71 minutes, 38 seconds, according to a mission timeline released by SpaceX.

Wednesday’s flight is the seventh SpaceX launch to carry up Iridium Next payloads, which typically ride 10 at a time on the top of Falcon 9 rockets. The most recent Iridium satellite launch in May carried five of the company’s spacecraft, with the rest of the rocket’s capacity going toward a pair of U.S.-German climate research probes in a rideshare mission.

Ten more Iridium Next satellites are scheduled to launch later this year, bringing the total number of new-generation craft launched to 75. Six additional spacecraft are under construction by Northrop Grumman and Thales Alenia Space at a factory in Arizona to be held in reserve as ground spares.

The Iridium Next satellites provide improved global telephone and messaging services for the company’s one million subscribers, replacing an aging fleet of spacecraft launched in the late 1990s and early 2000s.

Quelle: SN

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