Spacecraft design: Difference between revisions

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'''Spacecraft design''' is a process where [[systems engineering]] principles are systemically applied in order to construct complex [[spacecraft|vehicles]] for missions involving [[spaceflight|travel]], [[Space force|operation]] or [[space exploration|exploration]] in [[outer space]]. This design process produces the detailed [[design specification]]s, [[schematic]]s, and plans for the spacecraft system, including comprehensive [[documentation]] outlining the spacecraft's architecture, subsystems, components, interfaces, and operational requirements, and potentially some [[prototype]] models or [[simulation]]s, all of which taken together serve as the blueprint for manufacturing, assembly, integration, and testing of the spacecraft to ensure that it meets mission objectives and performance criteria.

<!--design phases and steps-->

Spacecraft design is conducted in several phases. Initially, a conceptual design is made to determine the feasibility and desirability of a new spacecraft system, showing that a credible design exists to carry out the mission. The conceptual design review ensures that the design meets the mission statement without any technical flaws while being internally consistent. Next, a preliminary design is carried out, where the focus is on functional performance, requirements definition, and interface definition at both subsystem and system levels. The preliminary design review evaluates the adequacy of the preliminary design. In the following phase, detailed design is drawn and coded for the system as a whole and all the subsystems, and a critical design review is performed where it is evaluated whether the design is sufficiently detailed to fabricate, integrate, and test the system.<ref name=Brown>{{Citation |title=Elements of Spacecraft Design |pages=13-17 |author=Charles D. Brown |publisher=American Institute of Aeronautics and Astronautics |year=2002}}</ref><ref name=Pisacane>{{Citation |title=Fundamentals of Space Systems |pages=11-15 |author=Vincent L. Pisacane |publisher=Oxford University Press |year=2005}}</ref>

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Throughout spacecraft design, potential risks are rigorously identified, assessed, and mitigated, systems components are properly integrated and comprehensively tested. The entire lifecycle (including launch, mission operations and end-of-mission disposal) is taken into account. An iterative process of reviews and testing is continuously employed to refine, optimize and enhance the design's effectiveness and reliability. In particular, the spacecraft's mass, power, thermal control, propulsion, altitude control, telecommunication, command and data, and structural aspects are taken into consideration. Choosing the right launch vehicle and adapting the design to the chosen launch vehicle is also important.<ref name=Brown/><ref name=Pisacane /> Regulatory compliance, adherence to International standards, designing for a sustainable, debris-free space environment are some other considerations that have become important in recent times.

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Spacecraft design includes the design of both [[robotic spacecraft]]s ([[satellite]]s and [[planetary probe]]s), and spacecrafts for [[human spaceflight]] ([[spacecraft|spaceship]]s and [[space station]]s). Human-carrying spacecrafts require additional life support systems, crew accommodations, and safety measures to support human occupants, as well as human factors engineering considerations such as ergonomics, crew comfort, and psychological well-being. Robotic spacecraftS require autonomy, reliability, and remote operation capabilities without human presence. The distinctive nature and the unique needs and constraints related to each of them significantly impact spacecraft design considerations.

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Recent developments in spacecraft design include [[Spacecraft electric propulsion|electric propulsion]] systems (e.g. [[ion thruster]]s and [[Hall-effect thruster]]s) for high-specific-impulse propulsion, [[solar sail]]s (using solar [[radiation pressure]]) for continuous thrust without the need for traditional rockets,<ref name=PopMech>{{Cite web |url=https://www.popularmechanics.com/space/satellites/a43635666/solar-sails-micro-satellites-future-of-space-exploration/ |author=Jackie Appel |title=Solar Sails and Micro-Satellites Might Be the Future of Space Exploration |website=Popular Mechanics |date=5 May 2023 |access-date=16 April 2024}}</ref> additive manufacturing ([[3D printing]]) and advanced materials (e.g. [[Advanced composite materials (engineering)|advanced composites]], [[nanomaterials]] and [[smart material]]s) for rapid prototyping and production of lightweight and durable components, [[artificial intelligence]] and [[machine learning]]-assisted autonomous systems for spacecraft autonomy and improved operational efficiency in long and faraway missions, [[in situ resource utilization]] (ISRU) technologies for extraction and utilization of local resources on celestial bodies, and [[CubeSat]]s and other standardized [[Small satellite|miniature satellite]]s<ref name=PopMech /> for cost-effective space missions around Earth.

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Spacecraft design involves experts from various fields such as engineering, physics, mathematics, computer science, etc. who come together to collaborate and participate in interdisciplinary teamwork. Furthermore, international collaboration and partnerships between space agencies, organizations, and countries help share expertise, resources, and capabilities for the mutual benefit of all parties. The challenges of spacecraft design drive technological innovation and engineering breakthroughs in professional and industrial sectors. The complexity of spacecraft design engages students in [[STEM]] subjects (science, technology, engineering, and mathematics), fosters scientific literacy and inspire the next generation of scientists, engineers, and innovators.

== Origin ==

{{Original research section|date=October 2011}}

Spacecraft design was born as a discipline in the 1950s and 60s with the advent of American and Soviet [[space exploration]] programs. Since then it has progressed, although typically less than comparable terrestrial technologies. This is for a large part due to the challenging space environment, but also to the lack of basic R&D, and other cultural factors within the design community. On the other hand, another reason for slow space travel application design is the high energy cost, and low efficiency, for achieving orbit. This cost might be seen as too high a "start-up cost."{{citation needed|date=December 2019}}

==Areas of engineering involved==

Spacecraft design brings together aspects of various disciplines, namely:{{citation needed|date=December 2019}}

* '''[[Systems engineering]]''' for maintaining the design baseline and derivation of [[subsystem]] [[requirements]],

* '''Communications engineering''' for the design of the subsystems that communicate with the ground (e.g. [[telemetry]]) and perform [[ranging]].

* '''[[Computer engineering]]''' for the design of the on-board [[computers]] and [[computer bus]]es. This subsystem is mainly based on terrestrial technologies, but unlike most of them, it must: cope with the space environment, be highly autonomous, and provide higher fault tolerance.

* '''[[Electrical engineering]]''' for the design of the power subsystem, which generates, stores, and distributes the [[electric power|electrical power]] to all the on-board equipment,

* '''[[Control theory]]''' for the design of the [[Spacecraft attitude control|attitude]] and [[orbit]] control subsystem, which points the spacecraft correctly, and maintains or changes the orbit according to the mission profile; the hardware used for actuation and sensing in space is usually very specific to spacecraft,

* '''Thermal engineering''' for the design of the [[spacecraft thermal control|thermal control]] subsystem (including radiators, iinsulation, ad heaters), which maintains environmental conditions compatible with operations of the spacecraft equipment; This subsystem has very space-specific technologies, since in space, [[radiation]] and [[Heat conduction|conduction]] usually dominate as thermal effects, by opposition with Earth where [[convection]] is typically the main one,

* '''[[Spacecraft propulsion|Propulsion]] engineering''' for the design of the propulsion subsystem, which providesa means of transporting the spacecraft from one orbit to another,

* '''[[Mechanical engineering]]''' for the design of the spacecraft structures and mechanisms, as well as the selection of [[materials for use in vacuum]]. These include beams, panels, and deployable appendages or separation devices (to separate from the [[launch vehicle]]).

{{main | spacecraft bus}}

{{main | spacecraft structure}}

The spacecraft bus carries the payload. Its subsystems support the payload and help in pointing the payload correctly. It puts the payload in the right orbit and keeps it there. It provides housekeeping functions. It also provides orbit and attitude maintenance, electric power, command, telemetry, and data handling, structure and rigidity, temperature control, data storage, and communication, if required. The payload and spacecraft bus may be different units or it may be a combined one. The booster adapter provides the load-carrying interface with the vehicle (payload and spacecraft bus together).

The spacecraft may also have a propellant load, which is used to drive or push the vehicle upwards, and a propulsion kick stage. The propellant commonly used is a compressed gas like nitrogen, a quid a such as monopropellant hydrazine or solid fuel, which is used for velocity corrections and attitude control. In a kick stage (also called apogee boost motor, propulsion module, or integral propulsion stage) a separate rocket motor is used to send the spacecraft into its mission orbit.

While designing a spacecraft, the orbit which is going to be used should be considered into thnt as it affects attitude control, thermal design, and the electric power subsystem. But these effects are secondary as compared to the effect caused on the payload due to the orbit. Thus while designing the mission; the designer selects such an orbit which increases the payload performance. The designer even calculates the required spacecraft performance characteristics such as pointing, thermal control, power quantity, and duty cycle. The spacecraft is then made, which satisfies all the requirements.{{citation needed|date=December 2019}}

{{ main | attitude control }}

The [[Attitude control system|attitude determination and control subsystem]] (ADCS) is used to change the attitude (orientation) of the spacecraft. There are some external [[torque]]s acting on the spacecraft along the axis passing through its [[center of gravity]] which can reorient the spacecraft in any direction or can give it a spin. The ADCS nullifies these torques by applying equal and opposite torques using the proion and navigation. Moment of inertia of the body is to be calculated to determine the external torques which also requires determination of vehicle's absolute attitude using sensors. The property called 'gyroscopic stiffness' is used to reduce the spinning effect.

The simplest spacecraft achieve control by spinning or interacting with the Earth's magnetic or gravity fields. Sometimes they are uncontrolled. Spacecraft may have several bodies or they are attached to important parts, such as solar arrays or communication antennas which need individual attitude pointing. For controlling the appendage's attitude, actuators are often used, with separate sensors and controllers.

The various types of control techniques used are:{{citation needed|date=December 2019}}

===Telemetry, tracking, and command===

{{ main | Telemetry }}

* Controlling of spacecraft by the operator on Earth

* Receive<!-- SPELLING NOTE: this is not spelt recieve either --> the downlink commands from subsystems, process and transmit them to Earth.

The vast majority of spacecraft communicate using [[radio antenna]]s -- [[satellite communication]].{{citation needed|date=December 2019}}

A few spacecraft [[free-space optical communication|communicate using lasers]]—either directly to the ground as with [[LADEE]]; or between satellites as with [[OICETS]], [[Artemis (satellite)|Artemis]], [[Alphabus]], and the [[European Data Relay System]].

{{ main | spacecraft thermal control }}

Thermal control subsystem (TCS) is used to maintain the temperature of all spacecraft components within certain limits. Both upper and lower limits are defined for each component. There are two limits, namely, operational (in working conditions) and survival (in non-working conditions). Temperature is controlled by using insulators, radiators, heaters, louvers and by giving proper surface finish to components.{{citation needed|date=December 2019}}

{{ main | spacecraft propulsion }}

[[File:NasaManned mission to Mars.jpg|thumb|An example architecture from the mid-2010s of a human spaceflight mission to Mars, as envisioned by the United States space agency, NASA.]]

== Space mission architecture ==

Spacecraft design is always informed by the particular mission architecture of the spaceflight under consideration. Typically, a variety of mission architectures can be envisioned that would achieve the overall objective of the flight, whether those objectives be to gather scientific data or merely [[space transport|transport]] cargo across the space environment to serve any variety of purposes, governmental or economic.<ref name=wertz1999>{{cite book |last=Wertz|first=James R. |last2=Larson|first2=Wiley J. |title=Space Mission Analysis and Design |edition=3rd |publisher=Kluwer Academic Publishers |year=1999 | isbn=1-881883-10-8 }}</ref>

Spaceflight mission architectures will specify whether a spacecraft is to be [[autonomous robot|autonomous]] or [[telerobotics|telerobotic]], or even be [[human spaceflight|crewed]] so as to deal with particular exigencies or goals of the mission. Other considerations include fast or slow trajectories, payload makeup and capacity, length of the mission, or the level of system redundancy so that the flight can achieve various degrees of [[fault-tolerance]].<ref name=wertz1999/>

==References==

* {{cite magazine|title = Solar sails fly from science fiction into reality|url=http://www.popularmechanics.com/science/space/news/solar-sails-fly-from-science-fiction-into-reality|magazine=Popular Mechanics}}

==External links==

*{{Commonscatinline|Spacecraft design}}

{{Design}}

[[Category:Spacecraft design| ]]