This paper presents a real-time algorithm for powered descent guidance, focusing on scenarios with non-convex constraints like obstacles or keep-out zones. It utilizes a novel Sequential Convex Programming (SCP) approach that reformulates the non-convex problem into a sequence of convex subproblems. These subproblems are solved efficiently using a custom interior-point method, enabling rapid trajectory generation suitable for online implementation. The algorithm's performance is validated through simulations of lunar landing scenarios demonstrating its ability to generate feasible and fuel-efficient trajectories while respecting complex constraints, even in the presence of disturbances. Furthermore, its computational speed is shown to be significantly faster than existing methods, making it a promising candidate for real-world powered descent applications.
Botswana successfully launched its first satellite, Botsat-1, into orbit. Developed in partnership with the University of Rome and launched aboard a SpaceX Falcon 9 rocket, the satellite will primarily focus on environmental monitoring, including land and water resource management, as well as disaster management. The project aims to enhance Botswana's technological capabilities, train local engineers, and provide valuable data for sustainable development initiatives.
HN commenters express excitement for Botswana's achievement, viewing it as a significant step for the country and the African space industry. Several highlight the potential for future Earth observation applications, particularly in managing natural resources and disaster response. Some discuss the technical aspects, noting the use of a SpaceX Falcon 9 rideshare and the satellite's relatively low cost. A few commenters caution against overhyping the achievement, emphasizing the need for sustained investment and development to build a thriving space program. Finally, there's discussion about the importance of international collaboration and technology transfer in facilitating such projects.
The "Whoosh Rocket" is a simple experiment demonstrating Newton's Third Law of Motion (for every action, there's an equal and opposite reaction). A plastic bottle, partially filled with water and pressurized with air, launches upwards when the air is released. The compressed air exerts force equally in all directions inside the bottle. When the stopper is removed, the air rushes out the opening, creating thrust. This downward force of the escaping air creates an equal and opposite upward force on the bottle, propelling it skyward. The amount of water affects the rocket's performance – too little and there isn't enough mass to be propelled efficiently; too much and the extra weight hinders its flight.
The Hacker News comments on the NASA "Whoosh Rocket" article largely focus on the surprising amount of thrust generated by this simple demonstration. Several commenters express fascination with the physics involved and the counterintuitive nature of the thrust being independent of the surrounding air pressure. Some discuss the educational value of the experiment, highlighting its simplicity and effectiveness in illustrating fundamental principles of rocket propulsion. One commenter provides further context by linking to a video demonstrating the experiment in a vacuum chamber, reinforcing the concept of thrust being generated solely by the expelled propellant. Another points out the historical significance of the experiment, linking it to a similar demonstration performed by Robert Goddard, considered the father of modern rocketry. There's a brief discussion comparing this type of rocket to other propulsion systems, and one user asks a clarifying question about the relevance of nozzle shape.
Spaceium, a YC S24 startup building a collaborative 3D world for space simulations and mission design, is hiring a software engineer. They're looking for someone proficient in C++, familiar with 3D graphics and game engine development (Unreal Engine preferred), and interested in space exploration. The role involves developing core features for their platform, including physics simulations, user interface elements, and collaborative tools. Experience with distributed systems or cloud computing is a plus.
Several commenters on Hacker News expressed skepticism about the job posting due to the vague nature of the product description ("building software to help manage space missions") and the perceived buzzword-heavy language. Some questioned the actual technical challenges involved, suggesting the work might be more focused on mundane tasks like data entry and form filling rather than complex software engineering. Others pointed out the low salary range ($60k-$100k) relative to the Bay Area and the experience level sought, especially for a YC-backed company. A few commenters defended the posting, noting that early-stage startups often lack detailed product information and that the salary might be reasonable depending on equity offered. The most compelling comments highlighted the mismatch between the ambitious vision presented and the seemingly low compensation and unexciting potential work involved.
A high school team designed and built a space probe named Project Daedalus, launched via high-altitude balloon. The probe, constructed using off-the-shelf components and custom PCBs, collected data on temperature, pressure, radiation, magnetic fields, and air quality during its flight. It also captured images and video throughout the ascent and descent. Successful data retrieval was achieved after landing, showcasing the team's ability to create a functional space probe on a limited budget.
The Hacker News comments express admiration for the high school team's ambitious space probe project, with several commenters praising the students' ingenuity and technical skills. Some discuss the challenges of high-altitude ballooning, offering advice on potential improvements like using a GPS tracker with an external antenna and considering the impact of the balloon bursting on the probe's descent. Others inquire about specific aspects of the project, such as the choice of microcontroller and the method of image transmission. The overall sentiment is one of encouragement and interest in the team's future endeavors.
The Washington Post reports that the FAA is potentially favoring SpaceX's Starlink over a Verizon contract for a Federal Aviation Administration (FAA) program to modernize its communication systems. The FAA appears poised to award SpaceX a significant portion, if not all, of the contract, despite Verizon seemingly being the frontrunner initially. This shift raises concerns about potential conflicts of interest due to Elon Musk's involvement with both SpaceX and Twitter, a platform frequently used by the FAA for disseminating critical information. The decision also sparks questions about the FAA's procurement process and whether SpaceX's technology truly surpasses Verizon's established infrastructure for the agency's needs.
HN commenters are largely skeptical of the premise that the FAA is intentionally favoring SpaceX. Several point out that Verizon's proposed use of the C-band spectrum interferes with existing FAA equipment, requiring mitigation efforts which Verizon seemingly hasn't fully addressed. Others suggest the FAA's concerns are legitimate and not related to any SpaceX lobbying, citing safety as the primary driver. Some also note the different nature of Starlink's operations (satellite-based) compared to Verizon's ground-based systems, suggesting a direct comparison and accusation of favoritism isn't warranted. A few comments mention the revolving door between government agencies and private companies as a potential factor, but this isn't a dominant theme.
Building a jet engine is incredibly difficult due to the extreme conditions and tight tolerances involved. The core operates at temperatures exceeding the melting point of its components, requiring advanced materials, intricate cooling systems, and precise manufacturing. Furthermore, the immense speeds and pressures within the engine necessitate incredibly balanced and durable rotating parts. Developing and integrating all these elements, while maintaining efficiency and reliability, presents a massive engineering challenge, requiring extensive testing and specialized knowledge.
Hacker News commenters generally agreed with the article's premise about the difficulty of jet engine manufacturing. Several highlighted the extreme tolerances required, comparing them to the width of a human hair. Some expanded on specific challenges like material science limitations at high temperatures and pressures, the complex interplay of fluid dynamics, thermodynamics, and mechanical engineering, and the rigorous testing and certification process. Others pointed out the geopolitical implications, with only a handful of countries possessing the capability, and discussed the potential for future innovations like 3D printing. A few commenters with relevant experience validated the author's points, adding further details on the intricacies of the manufacturing and maintenance processes. Some discussion also revolved around the contrast between the apparent simplicity of the Brayton cycle versus the actual engineering complexity required for its implementation in a jet engine.
Hybrid Air Vehicles' Pathfinder 1 airship, a massive aircraft blending airplane and airship technologies, recently completed its maiden voyage, marking a potential revival of airship travel. This innovative design uses helium for lift, supplemented by four propellers for thrust and control, allowing for shorter take-off and landing distances than traditional airships. Pathfinder 1 aims to demonstrate the viability of this technology for cargo transport, potentially revolutionizing logistics in remote or infrastructure-poor regions by offering a more fuel-efficient and environmentally friendly alternative to traditional air freight. Future iterations, including the larger Airlander 50, are planned for carrying heavier payloads and even passengers, possibly ushering in a new era of sustainable and accessible air travel.
Hacker News commenters discuss the practicality and potential of airships like Pathfinder 1. Skepticism centers around the actual carrying capacity compared to maritime shipping, the slow speed making them unsuitable for most cargo, and the historical safety concerns associated with large airships. Some highlight the niche applications where airships could be valuable, such as delivering large, indivisible goods to remote locations without port access, or luxury tourism. Several commenters mention the environmental benefits compared to traditional air freight, while others question if helium availability is sufficient for large-scale airship operations. A few point out the "vaporware" aspect of such projects, citing the long history of ambitious airship concepts that never materialized. The discussion also touches on the regulatory hurdles, particularly regarding airspace management, and the potential military applications of the technology.
SpinLaunch is developing a kinetic energy launch system that uses a massive rotating vacuum-sealed centrifuge to accelerate projectiles containing satellites to hypersonic speeds before releasing them for launch into orbit. This approach aims to significantly reduce the fuel required for space access, lowering costs and environmental impact compared to traditional rocket launches. While the system imparts substantial g-forces, SpinLaunch asserts its satellite deployment technology can withstand these stresses, enabling a new class of smaller, more robust, and cost-effective spacecraft.
Hacker News commenters express skepticism about SpinLaunch's claims and long-term viability. Several question the practicality and cost-effectiveness compared to traditional rocket launches, citing the immense g-forces involved and the potential limitations on payload size and fragility. Doubts are raised about the ability to scale the technology for larger payloads and the actual altitude achieved by the projectile, with some suggesting it merely reaches a high altitude rather than true orbit. Others point to the inherent challenges of atmospheric re-entry for the reusable part of the system. While acknowledging the innovative approach, the overall sentiment leans towards cautious pessimism, pending further demonstration of the technology's capabilities and economic viability. Some commenters also discussed the potential military applications and expressed concern about the weaponization of this technology.
Residents of the Turks and Caicos Islands are grappling with the aftermath of SpaceX's Starship explosion in April 2023. The powerful blast, which occurred during the rocket's first integrated flight test, scattered debris across the uninhabited island that served as the launch site. Months later, islanders are still finding chunks of concrete and metal, raising concerns about environmental damage and potential health risks. Clean-up efforts are slow and complex due to the remote location and the nature of the debris, leaving residents frustrated with the lack of progress and communication from SpaceX. The explosion's impact has underscored the potential downsides of commercial space launches and raised questions about adequate safety and mitigation measures.
Hacker News commenters discuss the environmental impact of the Starship explosion and the debris field it created in the Turks and Caicos. Several express concern over the lack of apparent cleanup efforts by SpaceX and the potential long-term effects on the fragile island ecosystem. Some question the adequacy of the environmental review process and the FAA's oversight. A few commenters point out the inherent risks of space exploration and the need for iterative development, while others criticize the "move fast and break things" mentality applied to such a sensitive environment. The discussion also touches on the potential for legal action by residents and the challenges of holding SpaceX accountable for the cleanup. A recurring theme is the contrast between the excitement surrounding space exploration and the less glamorous, but crucial, responsibility of mitigating its environmental consequences.
Boom Supersonic's XB-1 demonstrator, a scaled prototype of the planned Overture supersonic passenger jet, completed its first flight. The video showcases the aircraft taking off, performing various maneuvers in the air, and landing successfully at Mojave Air and Space Port. This flight marks a significant milestone in Boom's development of Overture, intended to revive commercial supersonic travel. The XB-1 test program aims to validate key technologies and design choices for the larger airliner, including its aerodynamic performance at supersonic speeds.
Hacker News users discussed the XB-1's first supersonic flight, expressing cautious optimism and interest in the future of supersonic commercial travel. Several commenters brought up the Concorde as a point of comparison, highlighting the challenges of noise, fuel efficiency, and cost that ultimately grounded it. Some debated the potential market for supersonic flights, questioning whether a small, wealthy clientele would be enough to sustain the industry. Others focused on technical aspects, like the XB-1's smaller size and different engine placement compared to the Concorde, and wondered about the long-term viability of sustainable aviation fuels in this context. A few comments also touched on the regulatory hurdles and the sonic boom problem, acknowledging that overcoming these will be crucial for the success of supersonic travel.
This video demonstrates a project-based learning approach to teaching math concepts, specifically using real-world examples from aerospace engineering. It showcases how principles of trigonometry and calculus can be applied to calculate things like rocket trajectories and orbital mechanics, making the math more engaging and relatable for students. The video emphasizes the practical application of these mathematical concepts within the context of exciting aerospace projects, aiming to inspire students and demonstrate the relevance of math in solving real-world problems.
HN users generally praised the video for its engaging approach to teaching math through real-world aerospace applications. Several commenters appreciated the clear explanations and the focus on practical examples, making complex concepts more accessible. Some discussed the presenter's effectiveness and charisma, while others highlighted the importance of connecting theoretical knowledge to tangible projects. A few users mentioned specific examples from the video that resonated with them, like the explanation of quaternions. There was also discussion around the broader educational implications of project-based learning and the value of making math more relevant to students.
Summary of Comments ( 3 )
https://news.ycombinator.com/item?id=43735960
HN users discuss the practical applications and limitations of the proposed powered descent guidance algorithm. Some express skepticism about its real-time performance on resource-constrained flight computers, particularly given the computational complexity introduced by the non-convex optimization. Others question the novelty of the approach, comparing it to existing methods and highlighting the challenges of verifying its robustness in unpredictable real-world scenarios like sudden wind gusts. The discussion also touches on the importance of accurate terrain data and the potential benefits for pinpoint landing accuracy, particularly in challenging environments like the lunar south pole. Several commenters ask for clarification on specific aspects of the algorithm and its implementation.
The Hacker News post titled "A Real-Time Algorithm for Non-Convex Powered Descent Guidance [pdf]" has a modest number of comments, focusing primarily on the practical applications and limitations of the proposed algorithm. There isn't a large, sprawling discussion, but the existing comments offer some interesting perspectives.
One commenter highlights the difficulty of real-time trajectory optimization, particularly in the context of unpredictable events like engine failures. They suggest this algorithm could be valuable for handling such contingencies, enabling rapid recalculation of a safe landing trajectory. This comment focuses on the robustness and adaptability of the approach in challenging scenarios.
Another comment chain discusses the algorithm's potential relevance to SpaceX landings. One participant questions whether SpaceX uses convex optimization for their landings, implying that a non-convex approach like the one proposed in the paper might offer advantages in terms of handling more complex constraints or optimizing for different parameters. Another user responds, suggesting that SpaceX likely utilizes some form of convex optimization, given its computational efficiency and the relatively predictable nature of their landing scenarios (barring unforeseen events). This exchange highlights the trade-offs between computational complexity and the ability to handle more general scenarios.
A further comment specifically mentions the challenge posed by non-convexity in optimization problems, emphasizing that local optima can trap traditional algorithms. They express interest in the paper's approach to overcoming this issue, indicating that finding globally optimal or near-optimal solutions in a non-convex space is a significant contribution.
Finally, one commenter notes the paper's focus on powered descent, contrasting it with ballistic entry, and highlighting the applicability of the algorithm to situations where continuous thrust control is available. This clarifies the specific domain of the research and its relevance to powered landing scenarios.
In summary, the comments on Hacker News don't delve deeply into the technical intricacies of the algorithm, but rather discuss its potential real-world implications, limitations, and the challenges inherent in the problem it addresses. They offer a valuable perspective on the practical significance of the research, complementing the theoretical content of the paper itself.