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Friday, September 17, 2021

Dzogchen

From Wikipedia, the free encyclopedia

A white Tibetan letter A inside a rainbow thigle is a common symbol of Dzogchen.
 
Dzogchen
Tibetan name
Tibetan རྫོགས་ཆེན་
Chinese name
Traditional Chinese大究竟、
大圓滿
大成就
Simplified Chinese大究竟、
大圆满
大成就

Dzogchen (Wylie: rdzogs chen, "Great Perfection" or "Great Completion"), also known as atiyoga (utmost yoga), is a tradition of teachings in Indo-Tibetan Buddhism aimed at discovering and continuing in the ultimate ground of existence. The primordial ground (ghzi, "basis") is said to have the qualities of purity (i.e. emptiness), spontaneity (lhun grub, associated with luminous clarity) and compassion (thugs rje). The goal of Dzogchen is knowledge of this basis, this knowledge is called rigpa (Skt. vidyā). There are numerous spiritual practices taught in the various Dzogchen systems for awakening rigpa.

Etymology and concepts

Dzogchen is composed of two terms:

  • rdzogs – perfection, completion
  • chen – great

According to the 14th Dalai Lama, the term dzogchen may be a rendering of the Sanskrit term mahāsandhi.

The term initially referred to the "highest perfection" of Vajrayana deity yoga. Specifically it refers to the stage after the deity visualisation has been dissolved and one rests in the natural state of the innately luminous and pure mind. According to Sam van Schaik, in the 8th-century tantra Sarvabuddhasamāyoga, the term refers to "a realization of the nature of reality" which arises through the practice of tantric anuyoga practices which produce bliss. In the 10th and 11th century, when Dzogchen emerged as a separate vehicle to liberation in the Nyingma tradition, the term was used synonymously with the Sanskrit term ati yoga (primordial yoga).

Rigpa (knowledge) and ma rigpa (delusion)

A widespread simile for ignorance is the obscuration of the sun by clouds
 

Rigpa (Sanskrit: vidyā, "knowledge") is a central concept in Dzogchen. According to Ācārya Malcolm Smith:

A text from the Heart Essence of Vimalamitra called the Lamp Summarizing Vidyā (Rig pa bsdus pa’i sgronma) defines vidyā in the following way: "...vidyā is knowing, clear, and unchanging" In Sanskrit, the term vidyā and all its cognates imply consciousness, knowing, knowledge, science, intelligence, and so on. Simply put, vidyā means unconfused knowledge of the basis that is its own state.

Ma rigpa (avidyā) is the opposite of rigpa or knowledge. Ma rigpa is ignorance, delusion or unawareness, the failure to recognize the nature of the basis. An important theme in Dzogchen texts is explaining how ignorance arises from the basis or Dharmata, which is associated with ye shes or pristine consciousness. Automatically arising unawareness (lhan-skyes ma-rigpa) exists because the basis has a natural cognitive potentiality which gives rise to appearances. This is the ground for samsara and nirvana.

Traditional exegesis

The Mirror of the Heart of Vajrasattva (Dorje Sempa Nyinggi Melong), a major Dzogchen tantra, explains the term Dzog (Perfection) as follows:

Because rigpa is perfect wisdom in the realm beyond effort, it is perfection. Because meditation is perfect stainless wisdom in the realm beyond concepts, it is perfection. Because behavior is perfect universal wisdom in the realm beyond correction, it is perfection. Because view is perfect non-conceptual wisdom in the realm beyond achievement, it is perfection. Because fruit is the perfect twenty-five wisdoms in the realm beyond frame of reference, it is perfection.

The Mirror of the Heart of Vajrasattva explains that Dzogchen is "great" because:

  • It is the pinnacle of all vehicles, views, meditations, behaviors, goals.
  • It is "never moving from the natural state."
  • It functions "without obstacles in the realm beyond change."
  • It manifests "beyond concepts in the realm beyond attachment."
  • It manifests "without attachment in the realm beyond desire"
  • It manifests "in great bliss in the realm beyond speech."
  • It is "the source that pervades pure enlightenment."
  • It is "non-substantial rigpa beyond action and effort."
  • It remains "in equality without moving from the realm of total bliss" and "without moving from the essential meaning."
  • It exists "everywhere without being a dimension of grasping."
  • It is "the essence of everything without being established with words and syllables."

History

Dzogchen developed in the Tibetan Empire period and the Era of Fragmentation (9th-11th centuries) and continues to be practiced today both in Tibet and around the world. It is a central teaching of the Yundrung Bon tradition as well as in the Nyingma school of Tibetan Buddhism. In these traditions, Dzogchen is the highest and most definitive path of the nine vehicles to liberation. Dzogchen is also practiced (to a lesser extent) in other Tibetan Buddhist schools, such as the Kagyu, Sakya and the Gelug schools.

Base, Path, and Fruit

The Base or Ground

An image of the Primordial Buddha Samantabhadra with his consort Samantabhadri. These images are said to symbolize the union of space (emptiness, the female aspect) and clarity - awareness (male).

A key concept in Dzogchen is the 'base', 'ground' or 'primordial state' (Tibetan: gzhi, Sanskrit: āśraya), also called the general ground (spyi gzhi) or the original ground (gdod ma'i gzhi). The basis is the original state "before realization produced buddhas and nonrealization produced sentient beings". It is atemporal and unchanging and yet it is "noetically potent", giving rise to mind (sems, Skt. citta), consciousness (shes pa, Skt. vijñāna), delusion (marigpa, Skt. avidyā) and knowledge (rigpa, Skt. vidyā). Furthermore, Hatchell notes that the Dzogchen tradition portrays ultimate reality as something which is "beyond the concepts of one and many."

Three qualities

According to the Dzogchen-teachings, the Ground or Buddha-nature has three qualities:

Herbert V. Guenther points out that this Ground is both a static potential and a dynamic unfolding. They give a process-orientated translation, to avoid any essentialist associations, since

ngo-bo (facticity) has nothing to do with nor can even be reduced to the (essentialist) categories of substance and quality; [...] rang-bzhin (actuality) remains open-dimensional, rather than being or turning into a rigid essence despite its being what it is; and that thugs-rje (resonance) is an atemporal sensitivity and response, rather than a distinct and narrowly circumscribed operation.

The 19th/20th-century Tibetan Buddhist scholar, Shechen Gyaltsap Gyurme Pema Namgyal, sees the Buddha-nature as ultimate truth, nirvana, which is constituted of profundity, primordial peace and radiance:

Buddha-nature is immaculate. It is profound, serene, unfabricated suchness, an uncompounded expanse of luminosity; nonarising, unceasing, primordial peace, spontaneously present nirvana.

Direct introduction

Pointing-out instruction

The pointing-out instruction (ngo sprod) is an introduction to the nature of mind in the Tibetan Buddhist lineages of Mahāmudrā and Dzogchen. In these traditions, a lama gives the pointing-out instruction in such a way that the disciple successfully recognizes the nature of mind.

The Path

There are three major divisions of the Dzogchen path, known as the "Three Dharmas of the Path." These are tawa, gompa, and chöpa. Namkhai Norbu translates these three terms as 'view,' 'practice,' and 'conduct.'

Garab Dorje's three statements

Garab Dorje.gif

Garab Dorje (c. 665) epitomized the Dzogchen teaching in three principles, known as "Striking the Vital Point in Three Statements" (Tsik Sum Né Dek), said to be his last words. They give in short the development a student has to undergo:

Garab Dorje's three statements were integrated into the Nyingthig traditions, the most popular of which in the Longchen Nyingthig by Jigme Lingpa (1730–1798). The statements are:

  1. Introducing directly the face of rigpa itself (ngo rang tok tu tré). Dudjom Rinpoche states this refers to: "Introducing directly the face of the naked mind as the rigpa itself, the innate primordial wisdom."
  2. Deciding upon one thing and one thing only (tak chik tok tu ché). Dujdom states: "Because all phenomena, whatever manifests, whether saṃsāra or nirvāṇa, are none other than the rigpa’s own play, there is complete and direct decision that there is nothing other than the abiding of the continual flow of rigpa."
  3. Confidence directly in the liberation of rising thoughts (deng drol tok tu cha). Dujdom comments: "In the recognition of namtok [arising thoughts], whatever arises, whether gross or subtle, there is direct confidence in the simultaneity of the arising and dissolution in the expanse of dharmakāya, which is the unity of rigpa and śūnyatā."

View

The metaphors of sky and spaciousness are often used to describe the nature of mind in Dzogchen.

Nyingma Dzogchen texts use unique terminology to describe the Dzogchen view (Tib. tawa). Some of these terms deal with the different elements and features of the mind and are drawn from classic Buddhist thought. The generic term for consciousness is shes pa (Skt. vijñāna), and includes the six sense consciousnesses. Worldly, impure and dualistic forms of consciousness are generally referred to with terms such as sems (citta, mind), yid (mānas) and blo (buddhi). On the other hand, nirvanic or liberated forms of consciousness are described with terms such as ye shes (jñāna, 'pristine consciousness') and shes rab (prajñā, wisdom). According to Sam van Schaik, two significant terms used in Dzogchen literature is the ground (gzhi) and gnosis (rig pa), which represent the "ontological and gnoseological aspects of the nirvanic state" respectively.

Nyingma Dzogchen literature also describes nirvana as the "expanse" or "space" (klong or dbyings) or the "expanse of Dharma" (chos dbyings, Sanskrit: Dharmadhatu). The term Dharmakaya (Dharma body) is also often associated with these terms in Dzogchen, as explained by Tulku Urgyen:

Dharmakaya is like space. You cannot say there is any limit to space in any direction. No matter how far you go, you never reach a point where space stops and that is the end of space. Space is infinite in all directions; so is dharmakaya. Dharmakaya is all-pervasive and totally infinite, beyond any confines or limitations. This is so for the dharmakaya of all buddhas. There is no individual dharmakaya for each buddha, as there is no individual space for each country.

The Dzogchen View of the secret instruction series (man ngag sde) is classically explained through the eleven vajra topics. These can be found in the String of Pearls Tantra (Mu tig phreng ba), the Great Commentary by Vimalamitra as well as in Longchenpa's Treasury of Word and Meaning (Tsik Dön Dzö).

Practice

Lukhang Temple mural depicting Dzogchen anuyoga practices such as tummo which work with the subtle body channels
 
Lukhang Temple mural depicting various Dzogchen practices
 
Lukhang mural

Dzogchen practice (gompa) relies on the view outlined above. However, according to Norbu, this is not an intellectual view, but a "direct, non-dual, non-conceptual knowledge" of fundamentally pure absolute nature which has become veiled by dualistic conditioning. In Dzogchen, one achieves this view through one's relationship with a guru or lama who introduces one to our own primordial state and provides instruction on how to practice. This "direct introduction" and transmission from a Dzogchen master is considered absolutely essential.

Dzogchen teachings emphasize naturalness, spontaneity and simplicity. Although Dzogchen is often portrayed as being distinct from or beyond tantra, Dzogchen traditions have incorporated many tantric concepts and practices. Dzogchen lineages embrace a varied array of traditions, that range from a systematic rejection of Buddhist tantra, to a full incorporation of tantric practices. The "main practices" are often considered advanced and thus preliminary practices and ritual initiation are generally seen as requirements.

The Dzogchen tradition contain vast anthologies and systems of practices, including Buddhist meditation, tantric yogas and unique Dzogchen methods. The earliest form of Dzogchen practice (the Semde, "Mind" series) generally emphasized non-symbolic "formless" practices (as opposed to tantric deity yoga). With the influence of Sarma tantra, the rise of the Seminal Heart tradition, and the systematisations of Longchenpa, the main Dzogchen practices came to be preceded by preliminary practices and infused with tantric practices.

Namkhai Norbu makes a distinction between Dzogchen "contemplation" proper (trekchö) and "meditation". According to Norbu, contemplation is "abiding in the non-dual state [i.e. rigpa] which, of its own nature, uninterruptedly self-liberates" while meditation is any practice "working with the dualistic, relative mind, in order to enable one to enter the state of contemplation." Norbu adds that all the various meditative practices found in Dzogchen teachings (such as the "six yogas") are simply means to help practitioners access rigpa and are thus "secondary."

Similarly, Achard notes that the core Dzogchen practice is the state of contemplation (dgongs pa) that refers to abiding in one's primordially pure state. This "could actually be described as an actual absence of particular practice" which is "devoid of action, effort and exertion" (such as tantric generation or completion practice). Furthermore, Achard notes that "for strict rDzogs chen practitioners, Guru-Yoga and Sky Gazing are the main means enabling the access to the state of Contemplation in a totally unaltered mode."

Preliminary practices

In Finding Ease in Meditation (bsam gtan ngal gso), Longchenpa outlines three main categories of preliminary practices. He stresses that these are necessary to the practice of Dzogchen and criticizes those who attempt to skip them.

The Longchen Nyingthig system divides preliminaries into ordinary and extraordinary types. The ordinary preliminaries are a series of contemplations of which there are two main instructional texts. One is based on Atisha's Seven Point Mind Training (Lojong) and is called the Tarpai Temke. The second is the Laglenla Deblug.

The extraordinary preliminaries are discussed in the Drenpa Nyerzhag.

According to Jigme Lingpa, the preliminary practices are the basis of the main practices, and thus, they are not to be abandoned at a later point. Norbu writes that the preliminaries are not compulsory in Dzogchen practice (only direct introduction is essential), instead, the preliminaries are only relatively useful depending on the capacity of individuals and how many obstacles they have in their practice of contemplation.

Lukhang Temple mural depicting physical yogas known as trulkhor

Another important requirement for practicing Dzogchen according to Jigme Lingpa is ritual initiation or empowerment (dbang) by an awakened lama. According to Tsoknyi Rinpoche, empowerment is necessary, as it plants the "seeds of realization" within the present body, speech and mind. Empowerment "invests us with the ability to be liberated into the already present ground." The practices bring the seeds to maturation, resulting in the qualities of enlightened body, speech and mind.

Following tantric initiation, one also engages in the tantric practices of the generation and completion stages of mahayoga and anuyoga. Jigme Lingpa sees all of these tantric practices as gradual steps to be cultivated which lead one to Great Perfection practice. Jigme Lingpa states:

What is the main point of the excellent path of greatness? It is no more than wiping clean intellectual limitations. Therefore the three vows, six paramitas, development and completion and so on are all steps on the ladder to the Great Perfection.

Rushen and sbyong ba
A yogi depicted using a meditation belt (gomthag) in the Lukhang Temple mural

Jigme Lingpa mentions two kinds of Dzogchen meditations (which can be used as preliminaries to trekchö) korde rushen, "making a gap between samsara and nirvana," and sbyong ba ("training").

Rushen are a series of visualisation and recitation exercises. The name reflects the dualism of the distinctions between mind and insight, ālaya and dharmakāya. Longchenpa places this practice in the "enhancement" (bogs dbyung) section of his concluding phase. It describes a practice "involving going to a solitary spot and acting out whatever comes to your mind."

Sbyong ba are a variety of teachings for training the body, speech and mind. The training of the body entails instructions for physical posture. The training of speech mainly entails recitation, especially of the syllable hūm. The training of the mind is a Madhyamaka-like analysis of the concept of the mind, to make clear that mind cannot arise from anywhere, reside anywhere, or go anywhere. They are in effect an establishment of emptiness by means of the intellect. According to Jigme Lingpa, these practices serve to purify the mind and pacify the hindrances.

Main practices

The actual Dzogchen meditation methods, which are unique to the tradition, appear in Seminal Heart texts such as Jigme Lingpa's Yeshe Lama and Longchenpa's Tsigdön Dzö and Tegchö Dzö. The presentation of Dzogchen meditation methods in the Yeshe Lama is divided into three parts:

  • Instructions for those of sharp faculties, which is where the actual Dzogchen meditation methods are found, such as trekchö and tögal.
  • Instructions for those of middling faculties, which discusses the bardo (intermediate state) of death andhow to practice during this phase
  • Instructions for those of lesser faculties, which discusses the transference of consciousness (phowa) at death to a pure land.
Contemplation
Yogis meditating on the letter A inside a thigle, Lukhang Temple

The Dzogchen meditation practices include a series of exercises known as semdzin (sems dzin), which literally means "to hold the mind" or "to fix mind." They include a whole range of methods, including fixation, breathing, and different body postures, all aiming to calm the mind and bring one into the state of contemplation. There are also methods of vipasyana (lhagthong) which works with the arising of thoughts. These practices can be found in all three Dzogchen series (Semde, Longde and Mennagde). Norbu considers these methods of samatha (shine) and vipasyana (lhagthong) to be "principal practices", even though they work with the mind and are not non-dual contemplation itself.

According to Namkhai Norbu, through these various methods one may arrive at "the state of non-dual contemplation" which is without doubts. At this stage, one must continue to remain in this state, which includes the practices of trekchö and tögal.

Trekchö
Yogis practicing Dzogchen, Lukhang Temple mural

Trekchö (khregs chod) means "(spontaneous) cutting of tension" or "cutting through solidity". The practice of trekchö reflects the earliest developments of Dzogchen, with its admonition against practice. In this practice one first identifies, and then sustains recognition of, one's own innately pure, empty awareness. The main trekchö instructions in the Lamrim Yeshe Nyingpo state "This instant freshness, unspoiled by the thoughts of the three times; You directly see in actuality by letting be in naturalness."

Tögal
Lukhang Temple mural depicting sky gazing visionary practice

Tögal (thod rgal) literally means "crossing the peak." It is sometimes translated as "leapover", "direct crossing", or "direct transcendence". Tögal is also called "the practice of vision", or "the practice of the Clear Light (od-gsal)". Jigme Lingpa follows Longchenpa in seeing the visionary practice of tögal as the highest level of meditation practice.

Bardo practice

For those of middle level capacities, Jigme Lingpa holds that they will attain awakening during the bardo or intermediate state during death, by following certain instructions on how to recognize the signs of death and how to practice during the death process. Jigme Lingpa describes the process as follows:

Thus, assuming [one of] the three postures or remaining in the sleeping-lion posture, focus awareness on the eyes. With eyes directed to the space of awareness, relinquish the present life and relax uncontrived within original purity. In an instant liberation will occur.

Jigme Lingpa also states one should practice this meditation while one is alive, to prepare for the death process meditation: "even while one is alive, when the sky is pristine, direct awareness into space and think, 'The moment of death has arrived. Now I must pass into the peaceful unelaborate expanse.' Exhale the breath and follow that by allowing the mind to remain without focus." Other meditations and techniques are taught as well, which should be practiced while one is alive.

Jigme Lingpa gives the following instructions, meant to be recited by a lama or fellow practitioner at the time of death. Various practices are also taught for those who are present when someone else is dying, such as the "three precious upadeshas of the great, profound tantra Conjunction of the Sun and Moon". These practices are meant to help the dying through the process and lead them to awakening or a higher rebirth.

Further practices related to the "bardo of the nature of phenomena" are also taught. At this point, one should practice trekchö and tögal. There are also specific instructions for this phase of death, which occurs when "the connection between body and mind has ended." According to Jigme Lingpa, at this stage, the consciousness of the basis of all dissolves into the basic space of phenomena and "in that instant, the natural clear light dawns like a cloudless autumn sky."

If one does not attain awakening, there will be a series of appearances which will be "extremely bright and colorful, devoid of distinctions such as outer, inner, wide, or narrow." There will also be appearances of the mandalas of peaceful and fierce deities. One is supposed to recognize all these appearances as being one's own mind and as lacking true existence.

Jigme Lingpa outlines the key point in bardo practice as follows:

The key point for achieving liberation in this way is to abide in unimpeded empty awareness, as the nature of original purity, beyond thought and expression. Having actually realized the ultimate ground of liberation, it is then necessary to encounter that which already is, decide upon that alone, and have confidence within liberation. Appearances by nature, when observed objectively, seem to be limitless; but, when observed subjectively, nothing whatsoever exists. However, even fixation upon the thought of nonexistence is naturally liberated in the first instant that one's own nature is nakedly revealed without mental analysis. This is the key point clearly defining the original ground of liberation. In whatever way compassion engages with objects, do not try to stop this pursuit or hold this within. With awareness placed precisely upon its own source, unimpeded cognition is without the distinctions of outer, inner, and between. In this way, the bardo appearances will be naturally pure in the radiance of awareness. This is a key point of the quintessential heart essence for recognizing the state of liberation with precise awareness.

Phowa (transference of consciousness)
Buddha Amitayus in his Pure Land Sukhavati.

Those beings of lesser faculties and limited potential will not attain awakening during the bardo but may transfer their consciousness (a practice called phowa) to a pure land once they have arrived at the "bardo of existence". Once they reach this bardo, they will recognize they have died and then they will recall the guru with faith and remember the instructions. Then they will think of the pure land and its qualities and they will be reborn there. In a pure land, beings can listen to the Dharma taught directly by Vajrasattva or some other Buddha. Jigme Lingpa recommends that one practice this in daily life as well.

Practice systems
Longchenpa's Natural Ease system

Longchenpa's Trilogy of Natural Ease (ngal gso skor gsum), is mainly a Semde (Mind Series) focused system, though it includes numerous elements from later more tantric systems. In the first volume of this trilogy, Finding Ease in the Nature of Mind (sems nyid ngal gso), Longchenpa outlines 141 contemplative practices, split into three sections: exoteric Buddhism (92), tantra (22), and the Great Perfection (27). This system remained influential in Tibet and was the main system taught by Patrul Rinpoche (1808-1887).

This system includes numerous contemplative practices including analytical contemplations into emptiness, calming (zhi gnas) practices (such as visualizing the channels, a deity or the breath), insight (lhag mthong) practices as well the integration (zung 'jug) of calming and insight (such as the practice of sky gazing or contemplating the mind). It also includes numerous contemplations which are formless and "technique free" and thus do not make sure of an object of focus (such as a tantric deity etc) and instead focus on intangible themes such as emptiness, the spaciousness of the mind and the illusory quality of appearances.

In the second book of the Trilogy of Natural Ease, Finding Ease in Meditation (bsam gtan ngal gso), Longchenpa uses the standard triad of meditative experiences (nyams) to present various practices: bliss (bde ba), radiance/clarity (gsal ba), and non-conceptuality (mi rtog pa), which is presented as corresponding to preliminaries, main practice, and concluding phase. The bliss practices are focused on tummo, "radiance" practices use the bodily winds/breath and visualization of light, and the practices dealing with non-conceptuality are based on contemplating the vastness of the sky.

The more conceptual meditations are relegated to the preliminary phase, while the main practices are formless and "direct" approaches supplemented by perfection stage techniques (i.e. anuyoga). Longchenpa includes the perfection phase techniques of channels, winds and nuclei into the main and concluding phases which also include new supporting contemplative techniques. However, unlike in other perfection stage practice systems, Longchenpa's perfection practices are extremely simple (spros med), and stress effortlessness and balance instead of complexity (spros bcas).

Jigme Linpa's Longchen Nyingthig system
Jigme Lingpa's systematization of the Seminal Heart tradition is one of the most influential systems of Dzogchen practice.

The teachings based on Jigme Lingpa's 18th century Longchen Nyingthig system are also divided into preliminary practices (ngondro, subdivided into various classes) and main practices (which are trekchö and tögal). In The White Lotus (rGyab brten padma dkar po), Jigme Lingpa outlines the path of Nyingthig Dzogchen practice as follows:

Your mindstream is purified by the profound initiation, which is the cause of ripening, and then you begin with the outer, inner and secret preliminaries, which can be equated with the path of accumulation in the Paramitayana. For beginners, the way of practicing is explained by the practice instructions and the lama's instructions.

According to Sam van Schaik, Jigme Lingpa's system of practice "represents both a graduated method and a gradual realization" which "stands in stark contrast to the discourse of the Great Perfection treasure texts," which defend a much more simultaneous form of practice.

Conduct

Norbu notes that "Tantric practices may be used as secondary practices by the practitioner of Dzogchen, alongside the principal practice of contemplation." Similarly, physical yoga (Tib. trulkhor) may also be used as supporting practices.

The Fruit

Self-liberation

According to Namkhai Norbu, in Dzogchen, "to become realized simply means to discover and manifest that which from the very beginning has been our own true condition: the Zhi (gzhi) or Base." Since the basis, the path of practice and the fruit or result of practice are non-dual from the ultimate perspective, in Dzogchen understands the path as not separate from the result or fruit of the path (i.e. Buddhahood). Once a Dzogchen practitioner has recognized their true nature (and "do not remain in doubt" regarding this), the path consists of the integration (sewa) of all experiences in their life with the state of rigpa. All these experiences are self-liberated through this integration or mixing.

This process is often explained through three "liberations" or capacities of a Dzogchen practitioner:

  • Cherdrol ("one observes and it liberates") - This is when an ordinary appearance occurs and one sees its true nature, which leads to its self-liberation. It is compared to how a drop of dew evaporates when the sunlight shines on it.
  • Shardrol ("as soon as it arises it liberates itself") - This occurs when any sense contact or passion arises self-liberates automatically and effortlessly. This is compared to how snow melts immediately on falling into the sea.
  • Rangdrol ("of itself it liberates itself"), according to Norbu, this is "completely non-dual and all-at-once, instantaneous self-liberation. Here the illusory separation of subject and object collapses of itself, and one's habitual vision, the limited cage, the trap of ego, opens out into the spacious vision of what is". The simile used here is a snake effortlessly unwinding its own body.

Advanced Dzogchen practitioners are also said to sometimes manifest supranormal knowledge (Skt. abhijñā, Tib. mngon shes), such as clairvoyance and telepathy.

Rainbow body

Tögal practice may lead to full Buddhahood and the self-liberation of the human body into a rainbow body at the moment of death, when all fixation and grasping has been exhausted. Tibetan Buddhism holds that the rainbow body is a nonmaterial body of light with the ability to exist and abide wherever and whenever as pointed by one's compassion. It is a manifestation of the sambhogakāya and its attainment is said to be accompanied by the appearance of lights and rainbows.

Some exceptional practitioners are held to have realized a higher type of rainbow body without dying (these include the 24 Bön masters from the oral tradition of Zhang Zhung, Tapihritsa, Padmasambhava, and Vimalamitra). Having completed the four visions before death, the individual focuses on the lights that surround the fingers. His or her physical body self-liberates into a nonmaterial body of light with the ability to exist and abide wherever and whenever as pointed by one's compassion.

Critique

Simultaneous and gradual practice

As noted by van Schaik, there is a tension in the Seminal Heart tradition of Dzgochen between methods which emphasize gradual practice and attainments, and methods which emphasize primordial liberation, simultaneous enlightenment, and non-activity. This seeming contradiction is explained by authors of the Seminal Heart tradition as being related to the different levels of ability of different practitioners.

For example, the works of Jigme Lingpa contain criticisms of methods which rely on cause and effect as well as methods that rely on intellectual analysis. Since Buddhahood is uncaused and transcendent of the intellect, these contrived and conceptual meditations are contrasted with "effortless" and "instantaneous" approaches in the works of Jigme Lingpa, who writes that as soon as a thought arises, it is to be seen nakedly, without analysis or examination. Similarly, a common theme of Dzogchen literature is the elevation of Dzogchen above all other "lower" ('og ma) vehicles and a criticism of these lower vehicles which are seen as inferior (dman pa) approaches.

In spite of these critiques, Dzogchen cycles like Jigme Lingpa's Longchen Nyingthig do contain numerous practices which are not instantaneous or effortless, such as tantric Mahayoga practice like deity yoga and preliminary methods such as ngondro (which are equated with the path of accumulation). Furthermore, Jigme Lingpa and Longchenpa also criticize those who teach the simultaneous method to everyone and teach them to dispense with all other methods at once.

In response to the idea that the gradualist teachings found in the Seminal Heart texts contradict the Dzogchen view of primordial liberation, Jigme Lingpa states:

This is not correct because Vajradhara using his skill in means, taught according to the categories of best, middling, and worst faculties, subdivided into the nine levels from sravaka to atiyoga. Although the Great Perfection is the path for those of the sharpest faculties, entrants are not composed exclusively of those types. With this in mind, having ascertained the features of the middling and inferior faculties of awareness holders, the tradition was established in this way.

This division of practices according to level of ability is also found in Longchenpa's Tegchö Dzö. However, as van Schaik notes, "the system should not be taken too literally. It is likely that all three types of instruction contained in the threefold structure of YL [Yeshe Lama] would be given to any one person." Therefore, though the instructions would be given to all student types, the actual capacity of the practitioner would determine how they would attain awakening (through Dzogchen meditation, in the bardo of death, or through transference of consciousness). Jigme Lingpa also believed that students of the superior faculties were extremely rare. He held that for most people, a gradual path of training is what is needed to reach realization.

Lunar resources

From Wikipedia, the free encyclopedia

 
An artificially colored mosaic constructed from a series of 53 images taken through three spectral filters by Galileo's imaging system as the spacecraft flew over the northern regions of the Moon on 7 December 1992. The colors indicate different materials.

A lunar anorthosite rock collected by the Apollo 16 crew from near the Descartes crater

The Moon bears substantial natural resources which could be exploited in the future. Potential lunar resources may encompass processable materials such as volatiles and minerals, along with geologic structures such as lava tubes that together, might enable lunar habitation. The use of resources on the Moon may provide a means of reducing the cost and risk of lunar exploration and beyond.

Insights about lunar resources gained from orbit and sample-return missions have greatly enhanced the understanding of the potential for in situ resource utilization (ISRU) at the Moon, but that knowledge is not yet sufficient to fully justify the commitment of large financial resources to implement an ISRU-based campaign. The determination of resource availability will drive the selection of sites for human settlement.

Overview

Lunar materials could facilitate continued exploration of the Moon itself, facilitate scientific and economic activity in the vicinity of both Earth and Moon (so-called cislunar space), or they could be imported to the Earth's surface where they would contribute directly to the global economy. Regolith (lunar soil) is the easiest product to obtain; it can provide radiation and micrometeoroid protection as well as construction and paving material by melting. Oxygen from lunar regolith oxides can be a source for metabolic oxygen and rocket propellant oxidizer. Water ice can provide water for radiation shielding, life-support, oxygen and rocket propellant feedstock. Volatiles from permanently shadowed craters may provide methane (CH
4
), ammonia (NH
3
), carbon dioxide (CO
2
) and carbon monoxide (CO). Metals and other elements for local industry may be obtained from the various minerals found in regolith.

The Moon is known to be poor in carbon and nitrogen, and rich in metals and in atomic oxygen, but their distribution and concentrations are still unknown. Further lunar exploration will reveal additional concentrations of economically useful materials, and whether or not these will be economically exploitable will depend on the value placed on them and on the energy and infrastructure available to support their extraction. For in situ resource utilization (ISRU) to be applied successfully on the Moon, landing site selection is imperative, as well as identifying suitable surface operations and technologies.

Scouting from lunar orbit by a few space agencies is ongoing, and landers and rovers are scouting resources and concentrations in situ.

Resources

Lunar surface chemical composition
Compound Formula Composition
Maria Highlands
silica SiO2 45.4% 45.5%
alumina Al2O3 14.9% 24.0%
lime CaO 11.8% 15.9%
iron(II) oxide FeO 14.1% 5.9%
magnesia MgO 9.2% 7.5%
titanium dioxide TiO2 3.9% 0.6%
sodium oxide Na2O 0.6% 0.6%
  99.9% 100.0%

Solar power, oxygen, and metals are abundant resources on the Moon. Elements known to be present on the lunar surface include, among others, hydrogen (H), oxygen (O), silicon (Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium (Ti). Among the more abundant are oxygen, iron and silicon. The atomic oxygen content in the regolith is estimated at 45% by weight.

Solar power

Daylight on the Moon lasts approximately two weeks, followed by approximately two weeks of night, while both lunar poles are illuminated almost constantly. The lunar south pole features a region with crater rims exposed to near constant solar illumination, yet the interior of the craters are permanently shaded from sunlight, and retain significant amounts of water ice in their interior. By locating a lunar resource processing facility near the lunar south pole, solar-generated electrical power would allow for nearly constant operation close to water ice sources.

Solar cells could be fabricated directly on the lunar soil by a medium-size (~200 kg) rover with the capabilities for heating the regolith, evaporation of the appropriate semiconductor materials for the solar cell structure directly on the regolith substrate, and deposition of metallic contacts and interconnects to finish off a complete solar cell array directly on the ground.

The Kilopower nuclear fission system is being developed for reliable electric power generation that could enable long-duration crewed bases on the Moon, Mars and destinations beyond. This system is ideal for locations on the Moon and Mars where power generation from sunlight is intermittent.

Oxygen

The elemental oxygen content in the regolith is estimated at 45% by weight. Oxygen is often found in iron-rich lunar minerals and glasses as iron oxide. At least twenty different possible processes for extracting oxygen from lunar regolith have been described, and all require high energy input: between 2-4 megawatt-years of energy (i.e. 6-12×1013 J) to produce 1,000 tons of oxygen. While oxygen extraction from metal oxides also produces useful metals, using water as a feedstock does not.

Water

Images by the LCROSS orbiter flying of the lunar south pole show areas of permanent shadow.
 
The image shows the distribution of surface ice at the Moon's south pole (left) and north pole (right) as viewed by NASA's Moon Mineralogy Mapper (M3) spectrometer onboard India's Chandrayaan-1 orbiter

Cumulative evidence from several orbiters strongly indicate that water ice is present on the surface at the Moon poles, but mostly on the south pole region. However, results from these datasets are not always correlated. It has been determined that the cumulative area of permanently shadowed lunar surface is 13,361 km2 in the northern hemisphere and 17,698 km2 in the southern hemisphere, giving a total area of 31,059 km2. The extent to which any or all of these permanently shadowed areas contain water ice and other volatiles is not currently known, so more data is needed about lunar ice deposits, its distribution, concentration, quantity, disposition, depth, geotechnical properties and any other characteristics necessary to design and develop extraction and processing systems. The intentional impact of the LCROSS orbiter into the Cabeus crater was monitored to analyze the resulting debris plume, and it was concluded that the water ice must be in the form of small (< ~10 cm), discrete pieces of ice distributed throughout the regolith, or as thin coating on ice grains. This, coupled with monostatic radar observations, suggest that the water ice present in the permanently shadowed regions of lunar polar craters is unlikely to be present in the form of thick, pure ice deposits.

Water may have been delivered to the Moon over geological timescales by the regular bombardment of water-bearing comets, asteroids and meteoroids  or continuously produced in situ by the hydrogen ions (protons) of the solar wind impacting oxygen-bearing minerals.

The lunar south pole features a region with crater rims exposed to near constant solar illumination, where the craters' interior are permanently shaded from sunlight, allowing for natural trapping and collection of water ice that could be mined in the future.

Water molecules (H
2
O
) can be broken down to its elements, namely hydrogen and oxygen, and form molecular hydrogen (H
2
) and molecular oxygen (O
2
) to be used as rocket bi-propellant or produce compounds for metallurgic and chemical production processes. Just the production of propellant, was estimated by a joint panel of industry, government and academic experts, identified a near-term annual demand of 450 metric tons of lunar-derived propellant equating to 2,450 metric tons of processed lunar water, generating US$2.4 billion of revenue annually.

Hydrogen

The solar wind implants protons on the regolith, forming a protonated atom, which is a chemical compound of hydrogen (H). Although bound hydrogen is plentiful, questions remain about how much of it diffuses into the subsurface, escapes into space or diffuses into cold traps. Hydrogen would be needed for propellant production, and it has a multitude of industrial uses. For example, hydrogen can be used for the production of oxygen by hydrogen reduction of ilmenite.

Metals

Iron

Common lunar minerals
Mineral Elements Lunar rock appearance
Plagioclase feldspar Calcium (Ca)
Aluminium (Al)
Silicon (Si)
Oxygen (O)
White to transparent gray; usually as elongated grains.
Pyroxene Iron (Fe),
Magnesium (Mg)
Calcium (Ca)
Silicon (Si)
Oxygen (O)
Maroon to black; the grains appear more elongated in the maria and more square in the highlands.
Olivine Iron (Fe)
Magnesium (Mg)
Silicon (Si)
Oxygen (O)
Greenish color; generally, it appears in a rounded shape.
Ilmenite Iron (Fe),
Titanium (Ti)
Oxygen (O)
Black, elongated square crystals.

Iron (Fe) is abundant in all mare basalts (~14-17 % per weight) but is mostly locked into silicate minerals (i.e. pyroxene and olivine) and into the oxide mineral ilmenite in the lowlands. Extraction would be quite energy-demanding, but some prominent lunar magnetic anomalies are suspected as being due to surviving Fe-rich meteoritic debris. Only further exploration in situ will determine whether or not this interpretation is correct, and how exploitable such meteoritic debris may be.

Free iron also exists in the regolith (0.5% by weight) naturally alloyed with nickel and cobalt and it can easily be extracted by simple magnets after grinding. This iron dust can be processed to make parts using powder metallurgy techniques, such as additive manufacturing, 3D printing, selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM).

Titanium

Titanium (Ti) can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace. It exists almost entirely in the mineral ilmenite (FeTiO3) in the range of 5-8% by weight. Ilmenite minerals also trap hydrogen (protons) from the solar wind, so that processing of ilmenite will also produce hydrogen, a valuable element on the Moon. The vast flood basalts on the northwest nearside (Mare Tranquillitatis) possess some of the highest titanium contents on the Moon, harboring 10 times as much titanium as rocks on Earth do.

Aluminium

Aluminium (Al) is found with a concentration in the range of 10-18% by weight, present in a mineral called anorthite (CaAl
2
Si
2
O
8
), the calcium endmember of the plagioclase feldspar mineral series. Aluminium is a good electrical conductor, and atomized aluminum powder also makes a good solid rocket fuel when burned with oxygen. Extraction of aluminium would also require breaking down plagioclase (CaAl2Si2O8).

Silicon

Photo of a piece of purified silicon

Silicon (Si) is an abundant metalloid in all lunar material, with a concentration of about 20% by weight. It is of enormous importance to produce solar panel arrays for the conversion of sunlight into electricity, as well as glass, fiber glass, and a variety of useful ceramics. Achieving a very high purity for use as semi-conductor would be challenging, especially in the lunar environment.

Calcium

Anorthite crystals in a basalt vug from Vesuvius, Italy (size: 6.9 × 4.1 × 3.8 cm)

Calcium (Ca) is the fourth most abundant element in the lunar highlands, present in anorthite minerals (formula CaAl
2
Si
2
O
8
). Calcium oxides and calcium silicates are not only useful for ceramics, but pure calcium metal is flexible and an excellent electrical conductor in the absence of oxygen. Anorthite is rare on the Earth but abundant on the Moon.

Calcium can also be used to fabricate silicon-based solar cells, requiring lunar silicon, iron, titanium oxide, calcium and aluminum.

Magnesium

Magnesium (Mg) is present in magmas and in the lunar minerals pyroxene and olivine, so it is suspected that magnesium is more abundant in the lower lunar crust. Magnesium has multiple uses as alloys for aerospace, automotive and electronics.

Rare-earth elements

Rare-earth elements are used to manufacture everything from electric or hybrid vehicles, wind turbines, electronic devices and clean energy technologies. Despite their name, rare-earth elements are – with the exception of promethium – relatively plentiful in Earth's crust. However, because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals; as a result, economically exploitable ore deposits are less common. Major reserves exist in China, California, India, Brazil, Australia, South Africa, and Malaysia, but China accounts for over 95% of the world's production of rare-earths.

Although current evidence suggests rare-earth elements are less abundant on the Moon than on Earth, NASA views the mining of rare-earth minerals as a viable lunar resource because they exhibit a wide range of industrially important optical, electrical, magnetic and catalytic properties.

Helium-3

By one estimate, the solar wind has deposited more than 1 million tons of helium-3 (3He) to the Moon's surface. Materials on the Moon's surface contain helium-3 at concentrations estimated between 1.4 and 15 parts per billion (ppb) in sunlit areas, and may contain concentrations as much as 50 ppb in permanently shadowed regions. For comparison, helium-3 in the Earth's atmosphere occurs at 7.2 parts per trillion (ppt).

A number of people since 1986 have proposed to exploit the lunar regolith and use the helium-3 for nuclear fusion, although as of 2020 functioning experimental nuclear fusion reactors have existed for decades - none of them has yet provided electricity commercially. Because of the low concentrations of helium-3, any mining equipment would need to process extremely large amounts of regolith. By one estimate, over 150 tons of regolith must be processed to obtain 1 gram (0.035 oz) of helium 3. China has begun the Chinese Lunar Exploration Program for exploring the Moon and is investigating the prospect of lunar mining, specifically looking for the isotope helium-3 for use as an energy source on Earth. Not all authors think the extraterrestrial extraction of helium-3 is feasible, and even if it was possible to extract helium-3 from the Moon, no fusion reactor design has produced more fusion power output than the electrical power input, defeating the purpose. Another downside is that it is a limited resource that can be exhausted once mined.

Carbon and nitrogen

Carbon (C) would be required for the production of lunar steel, but it is present in lunar regolith in trace amounts (82 ppm), contributed by the solar wind and micrometeorite impacts.

Nitrogen (N) was measured from soil samples brought back to Earth, and it exists as trace amounts at less than 5 ppm. It was found as isotopes 14N, 15N, and 16N. Carbon and fixed nitrogen would be required for farming activities within a sealed biosphere.

Regolith for construction

Developing a lunar economy will require a significant amount of infrastructure on the lunar surface, which will rely heavily on In situ resource utilization (ISRU) technologies to develop. One of the primary requirements will be to provide construction materials to build habitats, storage bins, landing pads, roads and other infrastructure. Unprocessed lunar soil, also called regolith, may be turned into usable structural components, through techniques such as sintering, hot-pressing, liquification, the cast basalt method, and 3D printing. Glass and glass fiber are straightforward to process on the Moon, and it was found regolith material strengths can be drastically improved by using glass fiber, such as 70% basalt glass fiber and 30% PETG mixture. Successful tests have been performed on Earth using some lunar regolith simulants, including MLS-1 and MLS-2.

The lunar soil, although it poses a problem for any mechanical moving parts, can be mixed with carbon nanotubes and epoxies in the construction of telescope mirrors up to 50 meters in diameter. Several craters near the poles are permanently dark and cold, a favorable environment for infrared telescopes.

Some proposals suggest to build a lunar base on the surface using modules brought from Earth, and covering them with lunar soil. The lunar soil is composed of a blend of silica and iron-containing compounds that may be fused into a glass-like solid using microwave radiation.

The European Space Agency working in 2013 with an independent architectural firm, tested a 3D-printed structure that could be constructed of lunar regolith for use as a Moon base. 3D-printed lunar soil would provide both "radiation and temperature insulation. Inside, a lightweight pressurized inflatable with the same dome shape would be the living environment for the first human Moon settlers."

In early 2014, NASA funded a small study at the University of Southern California to further develop the Contour Crafting 3D printing technique. Potential applications of this technology include constructing lunar structures of a material that could consist of up to 90-percent lunar material with only ten percent of the material requiring transport from Earth. NASA is also looking at a different technique that would involve the sintering of lunar dust using low-power (1500 watt) microwave radiation. The lunar material would be bound by heating to 1,200 to 1,500 °C (2,190 to 2,730 °F), somewhat below the melting point, in order to fuse the nanoparticle dust into a solid block that is ceramic-like, and would not require the transport of a binder material from Earth.

Mining

There are several models and proposals on how to exploit lunar resources, yet few of them consider sustainability. Long-term planning is required to achieve sustainability and ensure that future generations are not faced with a barren lunar wasteland by wanton practices. Lunar environmental sustainability must also adopt processes that do not use nor yield toxic material, and must minimize waste through recycling loops.

Scouting

Numerous orbiters have mapped the lunar surface composition, including Clementine, Lunar Reconnaissance Orbiter (LRO), Lunar Crater Observation and Sensing Satellite (LCROSS), Artemis orbiter, SELENE, Lunar Prospector, Chandrayaan, and Chang'e, to name a few, while the Soviet Luna programme and Apollo Program brought lunar samples back to Earth for extensive analyses. As of 2019, a new "Moon race" is ongoing that features prospecting for lunar resources to support crewed bases.

In the 21st century, China has taken the lead with the Chinese Lunar Exploration Program,[89][90] which is executing an ambitious, step-wise approach to incremental technology development and scouting for resources for a crewed base, projected for the 2030s. India's Chandrayaan programme is focused in understanding the lunar water cycle first, and on mapping mineral location and concentrations from orbit and in situ. Russia's Luna-Glob programme is planning and developing a series of landers, rovers and orbiters for prospecting and science exploration, and to eventually employ in situ resource utilization (ISRU) methods to construct and operate their own crewed lunar base in the 2030s.

The US has been studying the Moon for decades, but in 2019 it started to implement the Commercial Lunar Payload Services to support the crewed Artemis program, both aimed at scouting and exploiting lunar resources to facilitate a long-term crewed base on the Moon, and depending on the lessons learned, then move on to a crewed mission to Mars. NASA's lunar Resource Prospector rover was planned to prospect for resources on a polar region of the Moon, and it was to be launched in 2022. The mission concept was still in its pre-formulation stage, and a prototype rover was being tested when it was cancelled in April 2018. Its science instruments will be flown instead on several commercial lander missions contracted by NASA's new Commercial Lunar Payload Services (CLPS) program, that aims to focus on testing various lunar ISRU processes by landing several payloads on multiple commercial robotic landers and rovers. The first payload contracts were awarded on February 21, 2019, and will fly on separate missions. The CLPS will inform and support NASA's Artemis program, leading to a crewed lunar outpost for extended stays.

A European non-profit organization has called for a global synergistic collaboration between all space agencies and nations instead of a "Moon race"; this proposed collaborative concept is called the Moon Village. Moon Village seeks to create a vision where both international cooperation and the commercialization of space can thrive.

Some early private companies like Shackleton Energy Company, Deep Space Industries, Planetoid Mines, Golden Spike Company, Planetary Resources, Astrobotic Technology, and Moon Express are planning private commercial scouting and mining ventures on the Moon.

Extraction methods

The extensive lunar maria are composed of basaltic lava flows. Their mineralogy is dominated by a combination of five minerals: anorthites (CaAl2Si2O8), orthopyroxenes ((Mg,Fe)SiO
3
), clinopyroxenes (Ca(Fe,Mg)Si
2
O
6
), olivines ((Mg,Fe)
2
SiO
4
), and ilmenite (FeTiO
3
), all abundant on the Moon. It has been proposed that smelters could process the basaltic lava to break it down into pure calcium, aluminium, oxygen, iron, titanium, magnesium, and silica glass. Raw lunar anorthite could also be used for making fiberglass and other ceramic products. Another proposal envisions the use of fluorine brought from Earth as potassium fluoride to separate the raw materials from the lunar rocks.

Legal status of mining

Although Luna landers scattered pennants of the Soviet Union on the Moon, and United States flags were symbolically planted at their landing sites by the Apollo astronauts, no nation claims ownership of any part of the Moon's surface, and the international legal status of mining space resources is unclear and controversial.

The five treaties and agreements of international space law cover "non-appropriation of outer space by any one country, arms control, the freedom of exploration, liability for damage caused by space objects, the safety and rescue of spacecraft and astronauts, the prevention of harmful interference with space activities and the environment, the notification and registration of space activities, scientific investigation and the exploitation of natural resources in outer space and the settlement of disputes."

Russia, China, and the United States are party to the 1967 Outer Space Treaty (OST), which is the most widely adopted treaty, with 104 parties. The OST treaty offers imprecise guidelines to newer space activities such as lunar and asteroid mining, and it therefore remains under contention whether the extraction of resources falls within the prohibitive language of appropriation or whether the use encompasses the commercial use and exploitation. Although its applicability on exploiting natural resources remains in contention, leading experts generally agree with the position issued in 2015 by the International Institute of Space Law (ISSL) stating that, "in view of the absence of a clear prohibition of the taking of resources in the Outer Space Treaty, one can conclude that the use of space resources is permitted."

The 1979 Moon Treaty is a proposed framework of laws to develop a regime of detailed rules and procedures for orderly resource exploitation. This treaty would regulate exploitation of resources if it is "governed by an international regime" of rules (Article 11.5), but there has been no consensus and the precise rules for commercial mining have not been established. The Moon Treaty was ratified by very few nations, and thus suggested to have little to no relevancy in international law. The last attempt to define acceptable detailed rules for exploitation, ended in June 2018, after S. Neil Hosenball, who is the NASA General Counsel and chief US negotiator for the Moon Treaty, decided that negotiation of the mining rules in the Moon Treaty should be delayed until the feasibility of exploitation of lunar resources has been established.

Seeking clearer regulatory guidelines, private companies in the US prompted the US government, and legalized space mining in 2015 by introducing the US Commercial Space Launch Competitiveness Act of 2015. Similar national legislations legalizing extraterrestrial appropriation of resources are now being replicated by other nations, including Luxembourg, Japan, China, India and Russia. This has created an international legal controversy on mining rights for profit. A legal expert stated in 2011 that the international issues "would probably be settled during the normal course of space exploration." In April 2020, U.S. President Donald Trump signed an executive order to support moon mining.

See also

Titan II GLV

From Wikipedia, the free encyclopedia
 
Titan II GLV
Gemini-Titan 11 Launch - GPN-2000-001020.jpg

Launch of Gemini 11 on a Titan II GLV from LC-19
FunctionHuman-rated launch vehicle for Gemini spacecraft
ManufacturerMartin
Country of originUnited States
Size
Height109 ft (33 m)
Diameter10 ft (3.0 m)
Mass340,000 lb (150 t)
Stages2
Capacity
Payload to LEO
Mass7,900 lb (3.6 t)
Associated rockets
FamilyTitan
Launch history
StatusRetired
Launch sitesCape Canaveral LC-19
Total launches12
Success(es)12
First flightApril 8, 1964
Last flightNovember 11, 1966
Notable payloadsGemini

First stage
Engines1 LR87-AJ-7
Thrust430,000 lbf (1,900 kN)
Specific impulse258 s
Burn time156 seconds
PropellantAerozine 50 / N2O4
Second stage
Engines1 LR91-AJ-7
Thrust100,000 lbf (440 kN)
Specific impulse316 s
Burn time180 seconds
PropellantAerozine 50 / N2O4

The Titan II GLV (Gemini Launch Vehicle) or Gemini-Titan II was an American expendable launch system derived from the Titan II missile, which was used to launch twelve Gemini missions for NASA between 1964 and 1966. Two uncrewed launches followed by ten crewed ones were conducted from Launch Complex 19 at the Cape Canaveral Air Force Station, starting with Gemini 1 on April 8, 1964.

The Titan II was a two-stage liquid-fuel rocket, using a hypergolic propellant combination of Aerozine 50 fuel and nitrogen tetroxide oxidizer. The first stage was powered by an LR87 engine (with two combustion chambers and nozzles, fed by separate sets of turbomachinery), and the second stage was propelled by an LR-91 engine.

Modifications from the Titan II missile

In addition to greater payload capability, the Titan II promised greater reliability than the Atlas LV-3B, which had been selected for Project Mercury, because Titan's hypergolic-fueled engines contained far fewer components.

Several modifications were made to the Titan missile to human-rate it for Project Gemini:

  • A "Gemini Malfunction Detection System" was installed to inform the crew of the rocket's status, and improve response in an emergency.
  • Redundant systems were installed to reduce the chances of launch failures.
  • The inertial guidance system was replaced by a lighter-weight ground-radio guidance system
  • The avionics truss in the second stage was modified slightly
  • To help guard against the possibility of a guidance malfunction causing the engine nozzles to gimbal hard right or left, an extra backup guidance system was added.
  • The second stage propellant tanks were lengthened for longer burn time and unnecessary vernier engines and retrorockets were removed. Because the second stage engine had had issues with combustion instability, it was equipped with baffled injectors.
  • The first stage was loaded with 13,000 pounds (5.9 t) more propellant than the Titan ICBM although the storage tank size remained unchanged.
  • Modifications were made to the tracking, electrical and hydraulics systems in the interest of improved reliability.
  • The propellants were chilled to slightly improve vehicle performance. This allowed for more mass to be accommodated.
  • First stage engine thrust was reduced slightly to cut down on vibration and G loads.
  • First stage engine burn would go until propellant depletion unlike Titan ICBMs which were designed to cut off when propellant flow/pressure and engine thrust started dropping as the tanks emptied. This was to prevent the possibility of a malfunctioning pressure sensor triggering an abort condition. Also, running until depletion would slightly boost the Titan's capacity for payload.

Modifications were overseen by the Air Force Systems Command. The Aerojet company, the manufacturer of the Titan's engines, had released a revised model during mid-1963 due to deficiencies in the original design, and also to attempt to improve manufacturing procedures.

Film footage of Gemini 10's launch revealed that the first stage oxidizer tank ruptured shortly after staging and released a cloud of N2O4. As first stage telemetry had been terminated at staging, there was no data other than photographic/visual evidence to go by, however the conclusion was that either loose debris struck the oxidizer tank dome or else exhaust from the second stage engine had burned through it.

Gemini 12's launch vehicle also experienced a tank rupture after staging and film review of Titan II ICBM launches found several occurrences of this phenomenon. Since this did not appear to pose any safety risks to the astronauts, NASA decided that it was not a concern.

During Titan II ICBM development, it had been found that the first stage turbopump gearbox was prone to total failure caused by resonant vibration in the idler gear. This problem had not occurred on actual launches, but only static firing tests. This was considered to be a critical item to fix. Aerojet developed a totally redesigned gearbox, and all of Gemini launch vehicles except for the uncrewed Gemini 1 used it.

There was also a potentially serious problem with the turbopump bearings which led to more design changes, however the odds of failing on a Gemini launch were slim to nil since GLV boosters used specially selected and tested bearings, in addition the turbopumps would be "hot fired" as part of prelaunch checks.

Combustion instability in the second stage engine was also a concern although that too had only been witnessed in static firing runs. A new injector with improved baffling was developed for the engine and flight-tested on a Titan IIIC launch; all GLVs from Gemini 8 onwards incorporated it.

After a Titan II propellant feed line was found to have some damage during factory inspections, NASA put out the requirement that all GLV propellant lines had to be X-rayed in order to prevent a potentially disastrous fuel leak during launch. X-ray tests later found several more damaged propellant lines, most likely due to careless handling.

The most significant issue in man-rating the Titan II was resolving problems with resonant vibration known as "pogo" (since the action was said to resemble that of a pogo stick) that could produce g-forces sufficient to incapacitate astronauts, but the Air Force were not interested in helping NASA with a problem that did not affect the ICBM program and could potentially delay it, or require major modifications to the design. However, Martin-Marietta argued that the pogo problem could be fixed fairly easily, and also the Air Force began to develop more of an interest in man-rating the Titan II due to the proposed Manned Orbiting Laboratory program. The primary changes made to resolve pogo were adding oxidizer standpipes, increasing the pressure in the propellant tanks, and adding a mechanical accumulator to the fuel suction side.

Another nuisance problem that occurred during the Gemini program was code-named "Green Man" and involved momentary pitch oscillations of the Titan second stage following engine cutoff. This phenomenon had happened on both Gemini and uncrewed Titan II/III flights and had resulted in the failure of the ablative skirt on the second stage at least twice (those instances were dubbed "Brown Man"). Investigation following skirt failure on a Titan IIIC launch concluded that pressure buildup in the ablative skirt caused the pitch oscillations, but NASA decided that there was probably little chance of loose debris from the skirt contacting the Gemini spacecraft, so no corrective action had to be taken and in any case, the Titan IIIC incident was found to be the result of poor quality control which would not affect the more strictly supervised Gemini program.

The assembly of these rockets was done at Martin-Marietta's plant in Baltimore, Maryland, so not to interfere with missile work at the one in Denver, Colorado, although this also saved the former plant from a planned shutdown. As with the Mercury-Atlas launch vehicles, a high degree of workmanship was stressed as well as more thorough testing of components and improved handling procedures compared with Titans designed for uncrewed flights. 

Flights

Titan II GLV launches

The Titan II had a much higher thrust-to-weight ratio than the Saturn V. Astronauts experienced almost 6G before the second stage stopped firing at 100 miles (160 km) altitude. Richard F. Gordon Jr. compared the Titan II to "a young fighter pilot's ride. It's faster than the Saturn's old man's ride." Frank Borman said that simulations did not prepare him for the "almost deafening" noise, which he compared to a jet's afterburner or large train. Walter Schirra and Gordon Cooper reported that the ride was smoother than on the Atlas, however.

Mission LV serial No Launch date Crew
GT-1 GLV-1 12556 April 8, 1964 Uncrewed orbital test flight
GT-2 GLV-2 12557 January 19, 1965 Uncrewed suborbital test of Gemini heat shield
GT-3 GLV-3 12558 March 23, 1965 Gus Grissom and John Young
GT-IV GLV-4 12559 June 3, 1965 James McDivitt and Ed White
GT-V GLV-5 12560 August 21, 1965 Gordon Cooper and Charles P. Conrad
GT-VII GLV-7 12562 December 4, 1965 Frank Borman and Jim Lovell
GT-VI A GLV-6 12561 December 15, 1965 Wally Schirra and Thomas P. Stafford
GT-VIII GLV-8 12563 March 16, 1966 Neil Armstrong and David Scott
GT-IX A GLV-9 12564 June 3, 1966 Thomas P. Stafford and Eugene Cernan
GT-X GLV-10 12565 July 18, 1966 John Young and Michael Collins
GT-XI GLV-11 12566 September 12, 1966 Charles P. Conrad and Richard F. Gordon
GT-XII GLV-12 12567 November 11, 1966 Jim Lovell and Edwin "Buzz" Aldrin

See also


Inequality (mathematics)

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Inequality...