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By European Space Agency
The ESA/JAXA BepiColombo mission has successfully completed its fourth of six gravity assist flybys at Mercury, capturing images of two special impact craters as it uses the little planet’s gravity to steer itself on course to enter orbit around Mercury in November 2026.
The closest approach took place at 23:48 CEST (21:48 UTC) on 4 September 2024, with BepiColombo coming down to around 165 km above the planet’s surface. For the first time, the spacecraft had a clear view of Mercury’s south pole.
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA Marshall Space Flight Center: A thrust chamber assembly (TCA) is the critical and central component in a rocket engine that provides thrust to propel a launch vehicle into space. Since the 1960s, while small improvements in TCA performance have been made, little has been done to reduce weight, improve development timelines, and reduce manufacturing cost. This invention makes dramatic improvements in all three areas.
This Thrust Chamber Liner and Fabrication Method technology eliminates complex, bolted joints by using 3D printing and large-scale additive manufacturing (AM) to fabricate a one-piece TCA. This creates a combined combustion chamber and nozzle. A novel composite overwrap provides support with an overall mass reduction of >40%. The TCA is the heaviest component on the rocket engine, so every pound eliminated allows for additional payload. The benefits include significantly better performance of launch vehicles, consolidation of parts, and a simplified fabrication that reduces cost and lead time.
A liquid rocket engine provides thrust through the injection of a fuel and oxidizer into a combustion chamber then expanding the hot gases through a nozzle. The engine’s core component is the TCA, which comprises an injector, a combustion chamber, and a nozzle. To prevent the TCA’s wall material from reaching melting temperatures, a regenerative cooling system is employed. Small internal channels circulate either fuel or oxidizer as a coolant before it’s injected into the combustion chamber for the combustion process.
The TCA must withstand a wide range of challenges, including extreme temperatures (from cryogenic temperatures below -290 °F and up to +6,000°F), high pressures (up to 6,000 psi), demanding duty cycles that impact fatigue life, engine dynamics, and the reactive thrust loads. This necessitates the use of a variety of materials and involves intricate manufacturing and joining processes while maintaining exceptionally tight tolerances. The walls can be as thin as a few sheets of paper, measuring approximately 0.02 inch, increasing the complexity of the technological challenge.
The design and construction of the combined combustion chamber and nozzle has several novel features: (1) A NASA-developed alloy, Copper-Chrome-Niobium (GRCop-42) was matured for the combustion chamber resulting in a 45% increase in wall temperatures. (2) The integral channel design supports effective cooling, manifolds, and a range of features that facilitate an integrated coupled nozzle and composite overwrap. (3) The chamber and its internal structures are produced using a NASA-developed (and later commercialized) process known as laser powder bed fusion (L-PBF). This uses minimal exterior material, allowing the composite overwrap to effectively contain the high pressure and various engine loads. (4) Stock material and integral features build the chamber nozzle onto the aft end using a different alloy, optimizing the overall strength-to-weight ratio. (5) Traditionally, AM requires a build plate onto which parts are fabricated, but this innovation can use the chamber itself as the build plate. (6) A large-scale AM process called laser powder directed energy deposition (LP-DED) was developed with a new NASA alloy for hydrogen environments, called NASA HR-1 (HR = hydrogen resistant). The AM employed to integrate the chamber and nozzle involves the use of two distinct AM processes and alloys, using GRCop-42 for the chamber and NASA HR-1 for the nozzle.
A composite overwrap significantly reduces weight and provides adequate strength to sustain required pressures and loads. Various filament winding techniques and fiber orientations, guided by modeling simulations effectively counteract the (barrel) static pressure, startup, and shutdown loads, thrust, and gimbal loads. The unique locking features designed into the chamber include turn-around regions (referred to as “humps”) to eliminate complex tooling.
Traditional TCA design incorporates multiple manifolds, adding unnecessary weight and bolted or welded joints. These joints necessitate exceedingly tight tolerances, polished surface finishes, and intricate sealing mechanisms to prevent leakage. Maintaining precise concentricity among the components and ancillary features, such as shear-lips to avoid hot gas circulation and joint separation, is imperative. The risk of potential leakage can lead to the catastrophic failure of the engine or the entire vehicle. The tragic explosion of the Space Shuttle Challenger serves as a stark reminder of how joint failure, albeit in a solid rocket motor in that case, can have dire consequences. By contrast, this design eliminates these vulnerabilities by employing integrated AM processes to create a one-piece TCA, dramatically improving safety and efficiency.
Thrust Chamber Liner Team
Paul R. Gradl Christopher Stephen Protz Cory Ryan Medina Justin R. Jackson Omar Roberto Mireles Sandra Elam Greene William C. C. Brandsmeier Share
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Last Updated Jul 31, 2024 EditorBill Keeter Related Terms
Office of Technology, Policy and Strategy (OTPS) View the full article
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By NASA
Curiosity Navigation Curiosity Mission Overview Where is Curiosity? Mission Updates Science Overview Science Instruments Science Highlights News and Features Multimedia Curiosity Raw Images Mars Resources Mars Exploration All Planets Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto & Dwarf Planets 3 min read
Sols 4214–4215: The Best Laid Plans…
MAHLI image of “Mammoth Lakes,” which we had hoped would become our 41st drill hole after today’s plan. NASA/JPL-Caltech/MSSS Earth planning date: Wednesday, June 12, 2024
Planning today was defined by the decision about whether or not to drill at “Mammoth Lakes,” the potential drill target that we selected on Monday. This decision is made based on the answer to two questions. First, does this location meet our science objectives? On Monday, we undertook some exploratory contact science (primarily with APXS) to answer this question by determining the likely elemental composition of Mammoth Lakes. Second, is it safe to drill here? Monday’s plan also included a “preload test” to determine the safety of drilling by using the arm to place some pressure on Mammoth Lakes. We do these activities to measure the forces we expect on the arm while drilling and to see if the rock is stable enough to drill into. Although the APXS data indicated that this location meets our science objectives, the preload test was unsuccessful. Consequently, we had to pull the drill activities from the plan.
The drill activities had been scheduled to consume the entire first sol of this two sol plan. Unfortunately, the assessment of the preload data came too late to properly pivot from a drilling sol, so we were unable to plan any observations to replace the pulled drill activities. This means that Curiosity gets to take an unplanned vacation with just REMS and RAD observations on the first sol.
The second sol looks more like a typical plan, though we had to pull a number of drill-related activities here as well, so it’s a bit emptier than usual. We begin with a Mastcam tau observation looking at the amount of dust in the atmosphere, then move on to a set of Mastcam and Navcam photometry images. These photometry observations take several images of the ground near the rover at different times of day to help us understand how sunlight scatters off of the rocks around us. We take a quick break from science to let the rover communicate with Earth through the Mars Relay Network, then get right back to work with ChemCam. LIBS will be used on the target “Golden Trout Lake,” then we’ll get an RMI mosaic of an area about 15 metres away from the rover.
Once ChemCam is done, we’ll have our second set of Mastcam and Navcam photometry observations to complement those taken earlier in the sol. We’ll then take Mastcam images of the Golden Trout Lake LIBS target, one of ChemCam’s AEGIS targets, and some light-toned rocks at “Camp Four.” Mastcam will also be monitoring “Walker Lake,” a nearby patch of sand, to see how the wind is moving the sand around.
Today’s plan wraps up with a collection of environmental science activities, including a dust devil survey, suprahorizon movie, and a line-of-sight mosaic of the north crater rim, as well as our usual suite of REMS, DAN, and RAD observations.
Despite the challenges of today, we’re not giving up just yet. This isn’t our first failed preload test, so the team is now looking for somewhere else in this area to drill. Hopefully we won’t have the same difficulties as when we were trying to drill at the Marker Band, but nobody ever said that drilling a hole in a rock from over 270 million kilometres away was easy!
Written by Conor Hayes, Graduate Student at York University
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Last Updated Jun 13, 2024 Related Terms
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By European Space Agency
A team of European scientists have published the most detailed geologic map of Oxia Planum – the landing site for ESA’s Rosalind Franklin rover on Mars. This thorough look at the geography and geological history of the area will help the rover scout the once water-rich terrain, in the search for signs of past and present life.
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