Ramlaen
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Posts posted by Ramlaen
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A functioning RDE would be kind of a big deal.
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The Biden administration is pledging not to test destructive ground-launched anti-satellite missiles, a novel if narrow promise on the international stage, and is calling on other nations to follow suit to ensure the safety of the heavens.
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https://ntrs.nasa.gov/citations/20210026448
NASA’s Strategic Analysis Cycle 2021 (SAC21) Human Mars Architecture
QuoteThe National Aeronautics and Space Administration’s (NASA) Mars Architecture Team (MAT) was challenged to develop a mission architecture capable of transporting humans to the surface of Mars and back as fast—and as soon—as practical. This challenge represented a significant departure from previous approaches that minimized Earth-launched mass and maximized in-space transportation efficiency, often resulting in roundtrip missions of three years or more in duration. In the interest of crew health, MAT’s cross-Agency team of subject matter experts was challenged to develop an architecture capable of shortening crew time away from Earth to about two years. MAT was given specific mission constraints, such as number of crew, as well as mandates to minimize surface infrastructure as much as possible and to incorporate nuclear transportation options. The resulting MAT-developed concept, referred to here as the Strategic Analysis Cycle 2021 (SAC21) architecture, leverages Artemis elements and emerging commercial capabilities for cargo and logistics launches, and features a hybrid Nuclear Electric Propulsion (NEP)/Chemical transportation system able to complete the 1.8 billion kilometer round-trip journey to Mars and back in 760 to 850 days transit time for the 2039 Earth departure opportunity. Three Mars Descent Systems (MDS), each capable of landing about 25 metric tons of useful cargo on the surface of Mars, would be pre-deployed in advance of crew departure from Earth; two of these MDS’s would deliver a partially fueled Mars Ascent Vehicle (MAV), a fission power system, surface mobility, and additional MAV propellant. To minimize surface infrastructure, only two of the four Mars crew would descend and live in an MDS-landed pressurized rover, exploring the martian surface for 30 martian days, or sols, before returning to Mars orbit aboard their MAV and rejoining the other two crew on the Deep Space Transport for the Earth return voyage. Specifics of many of these architecture elements are detailed in separate technical publications; this paper outlines the end-to-end integrated architecture performance and concept of operations, including synergies with Artemis lunar architecture elements. It is important to note that NASA does not have a formal human Mars program and no decisions have been made; the architecture described here is intended to fill in an often-overlooked corner of the trade space, helping to complete the menu of options available to decision-makers as they chart the course for humans to Mars.
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https://ntrs.nasa.gov/citations/20210017131
Compass Final Report: Nuclear Electric Propulsion (NEP)-Chemical Vehicle 1.2
QuoteMany previous studies have examined sending crews to and from Mars. The most economical involved a
‘conjunction’ class whereby the crew spends around 500 days on Mars waiting for a ‘cheap’ return. The total
mission time results in over a 1000-day mission duration (about 3 years). Given the current experience level of only
one year on the International Space Station (ISS), it of interest to reduce that time to only two years, thus reducing
risk and minimizing required Mars surface infrastructure. The Phase 1.1 Study goal was stated as follows,
“Determine the feasibility of a two-year roundtrip class Mars mission concept of operation that enables boots on
Mars no later than 2036.” [1] While the Phase1 study did show feasibility for the NEP-Chemical option, the 2036
Opposition opportunity was found to stress the schedule due to proposed technology development schedules. A
2039 Opposition (which requires even more energy than the 2036 case) was chosen as representative for Phase 1.2.
Phase 1.2 also sought to further refine the concept, building on the feasibility, but addressing several challenges
brought by the red team and habitat team.
Given the date of 2039, nearer term technologies, primarily nuclear thermal and nuclear electric were deemed as the
most viable for these missions. As will be shown, the energy required to perform such a mission in only two years
(for the 2039 opportunity at least) is about three times that of the three-year conjunction mission. The rocket
equation (Equation 1 below) shows that this mission would then require several times the propellant of the three-
year mission unless the specific impulse (ISP) of the propulsion system can be increased.Based on lunar needs, a limit of five Space Launch System (SLS) launchers with 8.4 m fairings was imposed for the
piloted transportation portion of the mission, limiting the size of the system. When using nuclear electric propulsion,
the main limiting factor was packaging the required radiator area.
The higher I sp nuclear electric propulsion (NEP) system option is described herein but with a twist: in order to keep
the size of radiators packageable in one SLS and use proven reactor power system technology (~1200 K reactor
outlet temperature and superalloy-class Brayton) the NEP system had to be combined with a chemical propulsion
system. This combination of electric propulsion and high thrust chemical was found to be useful in previous design
studies combining solar electric propulsion (SEP) and chemical propulsion [2]. Such a combination allowed the low-
thrust system to provide significant change in velocity (∆V) during the interplanetary portions of the mission,
thereby notably reducing the ∆V required by the high thrust system to capture and depart from the Mars gravity
well. Here the high thrust ‘impulsive’ system is more efficient due to the Oberth Effect [3].
A plethora of trades, both at the mission and system level, as well as the subsystem level were performed to develop
these vehicle concepts. The most important will be described in each appropriate section in detail. A pictorial
summary showing the design evolution is shown in Figure 2-1.
An entire family of NEP-Chemical transportation vehicles is described herein. The main driver and the primary
focus was the piloted vehicle, shown in Figure 1-1, but additional concepts for cargo were performed using the same
‘building blocks’ in order to reduce costs and provide commonality. The cargo options are described in
APPENDIX B. -
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Quote
The first mission of the nuclear tug "Zeus" will include a search for life on the moons of Jupiter. Alexander Bloshenko, executive director of Roscosmos for advanced programs and science, spoke about this in an interview with Izvestia. According to him, the tug will fly around the Moon, head towards Venus, leave several satellites there, and finally begin its journey to Jupiter. There, "Zeus" will check the planet's satellites for biomarkers and conditions potentially suitable for the existence of life. The device is planned to be made in such a way that its power can be changed depending on the flight range and assigned mission.
Looking for life
- Alexander Vitalyevich, will it be possible to launch the Zeus nuclear tug into space?
- Experimental confirmation of key technologies and development of the conceptual part of the project documentation should be completed in 2024. Further, the tug project can begin to be implemented - first in the design bureaus, and then in iron in the shops. The first mission will take place in 2030. Now its parameters are calculated by scientists and specialists of various profiles. First, Zeus and the payload module, each on its own launch vehicle, will be launched into low-Earth orbit from the Vostochny cosmodrome. Further, their orbital docking will be carried out and a flight around the Moon and return to the Earth will be carried out. Then the docking with another payload module will be tested. Next, "Zeus" will fly towards Venus, perform a gravitational maneuver there and head towards the satellites of Jupiter. The duration of the mission will be 50 months, it will end around 2034. - Will the re-docking take place automatically? - Of course, since the presence of a nuclear reactor on Zeus does not imply the involvement of people on it today. And in general, the expediency of direct participation in human space missions at the current level of technological development is an open question that is being discussed all over the world. Life forms new current trends, and they are directed towards robotization, automation and the widespread use of artificial intelligence.
— How are you planning to load Zeus to solve the scientific problems of the first mission? “Our space scientists are planning to use the unique transport and energy capabilities of the Zeus to solve a wide range of scientific problems at all stages of the mission. At the first stage, the nuclear tug should provide radiophysical research of the Earth-Moon satellite. A powerful onboard radar complex, which includes several radars, will have to scan the lunar rocks under the regolith for lava tubes, cavities, accumulations of useful resources, including ice. Detailed maps of the surface and near-surface layer will be created, important properties and features of the soil will be studied - this will be useful for the implementation of the future lunar program. In the next stages, "Zeus" will go into deep space. A number of scientific satellites - probes are supposed to be delivered to Venus, as well as Jupiter and its satellites. I would like to explore the atmosphere, magnetosphere and internal energy sources of Jupiter, explore the subglacial oceans of Europa and Ganymede. In addition, we will check the moons of Jupiter for the presence of life there. More specifically, we plan to test the moons of Jupiter for the presence of so-called biomarkers and conditions potentially suitable for the existence of life.
Do you expect to find life there? - This, of course, would make a revolution in the consciousness of mankind, understanding of the role and place of us in the Universe. Today it is difficult to even imagine what a leap could take place in biochemistry, medicine, pharmacology, and in almost all areas of our activity. Therefore, we plan to at least look for it there. Today, Jupiter's moons - Io, Europa, Ganymede and Callisto - along with Saturn's moons Titan and Enceladus attract the closest attention of scientists around the world and are even considered as objects for colonization in the distant future. It has been established that some of them have oceans covered with ice, from under which steam sometimes comes out, some tectonic activity is observed, which indicates a hot core of a celestial body. Heat and water are the necessary conditions for the existence of life. Many missions are organized to the moons of Jupiter. However, in order to obtain reliable and complete information, it is necessary to deliver a large amount of high-tech equipment there - spectrometers, gas analyzers, multispectral cameras, and so on. It would be interesting to fly through the "exhaust" of steam, but this requires a separate special satellite, which Zeus can also bring as part of the payload module.
Difficult but possible - In the future, the range of tasks "Zeus" can expand significantly. Are you planning to make several tugs with different capacities? - You probably involuntarily asked two conceptual questions - about different missions using the Zeus and about different technical solutions of the Zeus itself. On the first question. I want to say right away that we are probably working with the best engineering staff. The designers of our design bureaus foresaw that in the future there would be a huge demand for Zeus as an interplanetary transport system. Therefore, its capabilities must be flexible in terms of scalability. A simple example. To minimize the flight time to the Moon and Jupiter, different engines are needed - because of the significantly different distances to these objects. Using the same engines to implement these tasks is simply inefficient. The same goes for fuel reserves and the design of fuel tanks, because they ultimately affect the mass of the delivered cargo. That is why the same Zeus will be used in flight to the Moon and Jupiter, but with different payload modules, which will include special main engines. - What about the second question? — Our country has been engaged in the development of space nuclear technologies quite a long time ago. In numerous publications you can find a lot of interesting things about this. The technology on which Zeus is based did not begin to develop and be mastered yesterday. Over the past decade, our enterprises have created a huge backlog that provides world leadership in this matter. We can create a tug with different capacities, but today we probably stopped at the golden mean - about 500 kW. From the point of view of the energy potential, this is enough to solve transport problems and provide energy for almost any payload. At the same time, from the point of view of design features, the solutions laid down are easily scaled on subsequent modifications of the tug up to 1 MW. In addition, to ensure maximum flexibility and durability of such a complex transport system, Zeus's maintenance capabilities are being preliminarily studied. For example, this can be done using a multifunctional reusable cruise ship capable of not only refueling the tug with expendable components, but also providing, if necessary, diagnostics and repair operations.
A matter of technology How does Zeus work? - If you do not go into details at all, then everything is simple - this is an ordinary heat engine and replaceable energy consumers. The nuclear reactor - the heart of Zeus - can simply release a huge amount of heat that needs to be converted into electricity. Next comes the "technical fork" of design options. We settled on machine energy conversion. The coolant, passing through the core of a nuclear reactor, heats up and sets the “machine” in motion, in our case it spins a turbine with its steam, which makes the electric power generator work. In this case, the efficiency can reach up to 30%. Further, the electric power is transmitted to consumers on the payload module - sustainer engines, target equipment and on-board support systems. It was this option - as the most promising and effective, but also the most technologically complex - that was chosen for Zeus. — What components are the most difficult to design and develop? — The most complex elements are a reactor plant and an energy conversion system based on a gas turbine generator. I will not touch on the complexity and innovativeness of the reactor plant, since it is the "eparchy" of another state corporation (Rosatom), but I will focus on the energy conversion system. Imagine a turbine and a generator rotating at a speed of 1 thousand revolutions per second at a temperature on the turbine blades of about 1.5 thousand degrees Kelvin (about 1.2 thousand degrees Celsius. - Izvestia). Moreover, this entire system should work without failures in outer space at a very large distance from the Earth for at least 10 years. But that's not all. A little earlier we said that only 30% of thermal energy is converted into electrical energy. The remaining 70% of the heat must be disposed of through a heat recovery system. This is a very difficult task in outer space, since this is possible only through thermal radiation, because there is no direct exchange of heat with the environment - vacuum -. For this purpose, spacecraft are equipped with special surfaces that effectively emit in the infrared range of the spectrum, but in our case, at our energies, these surfaces turn into very large fields, becoming the most difficult design task for development and testing in ground conditions.
— Why does space technology take so long to make and is expensive? - Our developers - engineers, testers, workers, technologists - all understand the cost of a mistake, they simply do not have the right to it. The error means an idle spacecraft in orbit. Unfortunately, while humanity does not have the technology for a full-fledged repair in orbit, this is why the price of a mistake is so high. Of course, our predecessors, we, our followers had and will have ups and downs, but we here on Earth, in the course of designing, designing, manufacturing, and experimental testing, strive to do everything to eliminate emergency situations as much as possible. To do this, at each stage of work, everything is repeatedly checked, each component of the spacecraft first undergoes autonomous tests that simulate its entire life cycle, from leaving the shop gate to the completion of the flight in space, then comprehensive tests as part of a larger system or unit, and so on. , before testing the fully assembled spacecraft on Earth. We can say that time and money in space technology is the price for the highest reliability. - Can external factors hinder the implementation of such an ambitious project? “We live in difficult times. We recently overcame the pandemic, and today we are forced to live under unprecedented sanctions pressure from foreign competitors. Conditions are unpredictable, and all sectors of the economy, including the financial sector, are affected by them. Despite this, in my opinion, priority projects, where our leadership is still obvious, should be supported at all levels of executive power, and we and our colleagues from the industry will not let us down. -
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Lynx with rubber tracks has evolved into Lynx having vibration issues?
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Dean said the source-selection phase of the competition is ongoing and the program is on schedule for a production decision in the third quarter of fiscal 2022 — around June. The plan is to equip the first unit with MPF by the fourth quarter of FY25.
The Army plans to initially build 26 vehicles, with an option to build 28 more and retrofit eight prototypes.
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Main Ground Combat System (MGCS) and Euro Main Battle Tank (EMBT)
in Mechanized Warfare
Posted
Well it's a choice of buying the best fighter available in both performance and value or supporting local industry which may or may not make something comperable in 20 years assuming another Typhoon/Rafale split doesn't happen.