Search This Blog

Tuesday, October 17, 2023

Christian Zionism

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Christian_Zionism
"Memorandum to Protestant Monarchs of Europe for the restoration of the Jews to Palestine" (1841, Colonial Times)

Christian Zionism is an ideology that, in a Christian context, espouses the return of the Jewish people to the Holy Land. Likewise, it holds that the founding of the State of Israel in 1948 was in accordance with Bible prophecy: that the re-establishment of Jewish sovereignty in the Levant — the eschatological "Gathering of Israel" — is a prerequisite for the Second Coming of Jesus Christ. The term began to be used in the mid-20th century, in place of Christian restorationism, as proponents of the ideology rallied behind Zionists in support of a Jewish national homeland.

Advocacy on the part of Christians for a Jewish restoration grew after the Reformation, and is rooted in 17th-century England. Contemporary Israeli historian Anita Shapira suggests that England's Zionist evangelical Christians "passed this notion on to Jewish circles" around the 1840s, while Jewish nationalism in the early 19th century was largely met with hostility from British Jews.

Christian pro-Zionist ideals have generally been common among Protestants since the Reformation. While supporting a mass Jewish return to the Land of Israel, Christian Zionism asserts a parallel idea that the returnees ought to be encouraged to reject Judaism and adopt Christianity as a means of fulfilling biblical prophecies. Polling has suggested a trend of widespread distrust among Jews towards the motives of Christian Zionists with regard to their particular pro-Jewish sentiment and their support for the Jewish state.

History before the 20th century

Origins in Calvinistic millennialism

Thomas Brightman, an English Puritan, published Shall They Return to Jerusalem Again? in 1615. This was one of the earliest Restorationist works.

Advocacy of the restoration of Palestine as a national homeland for the Jews was first heard among self-identified Christian groups in the 1580s following the Protestant Reformation. The first wave of Protestant leaders, including Martin Luther and John Calvin, did not mention any special eschatological views which included a return of the Jews to Palestine (converted to Christianity or otherwise). More generally, Luther had hoped that the Jews would convert to his brand of Christianity once he had broken with the Catholic Church, but later he harshly denounced Jews. Like the Catholic Church and the Eastern Orthodox Church, Luther and Calvin saw the Christian Church as being the "spiritual Israel" and since Jesus Christ, the covenant with God as being with faithful Christians exclusively as the "people of God", with no special privileges or role based on ancestral descent (in later times this has been called supersessionism). The Protestant focus on sola scriptura and the wider distribution of the Bible across Europe in the vernacular languages, however, allowed various radical protestants to interpret the scriptures in their own ways, in a manner which was not entirely reflective of either medieval Catholic tradition, or, the views of the early Protestant leaders themselves. Coupled with this was a general cultural Hebraising among more radical Protestants, as they saw the veneration of saints as idolatry and placed more focus on the Biblical prophets of the Old Testament, often naming their children Jeremiah, Zachary, Daniel, Sampson and the like.

While Edward VI of England was the Tudor child-monarch of England, a Calvinist-leaning Regency de facto ruled. This allowed Continental Protestants such as Martin Bucer and Peter Martyr Vermigli to teach at the prestigious universities of Cambridge and Oxford. These two men forwarded a biblical exegesis which included an important role for the Jews, converted to Christianity, in the end times. Early versions of the Bible endorsed by the English monarchy and the Anglican Church included the Great Bible and the Bishops' Bible. However, a number of English Puritans and Lowland Scots Presbyterians viewed these (along with Episcopalianism and the establishment "Protestantism of the princes"), in general, as too "Romanist." In response, a number of these Puritans and Presbyterians spent some time in Geneva in the 1560s under Calvin's successor Theodore Beza and developed a translation of the Bible called the Geneva Bible, which contained footnotes in reference to the Book of Romans, specifically claiming that the Jews would be converted to Christianity in the end times and reorientating attention to Palestine as a central theatre. This view came to be taken up strongly by English Puritans (such as Francis Kett, Edmund Bunny, Thomas Draxe, Thomas Brightman, Joseph Mede, William Perkins, Richard Sibbes, Thomas Goodwin, William Strong, William Bridge, Henry Finch, John Owen and Giles Fletcher), Lowland Scots Presbyterians (such as George Gillespie, Robert Baillie and Samuel Rutherford), and even some Continental Protestants (such as Oliger Paulli, Isaac Vossius, Hugo Grotius, Gerhard Vossius and David Blondel).

The Puritans, once a "fringe" faction, came to power under Oliver Cromwell during the Commonwealth. Several of his closest advisors held Philo-Semitic millennialist religious views.

During the late Tudor and early Stuart period, these Puritans remained outsiders in England and bitterly opposed the Laudian-dominated Anglican Church (though the Presbyterians, who held very similar views, had established the Church of Scotland as the largest "Kirk" in Scotland). With the English Civil War, the Puritans filled the ranks of the Parliamentarians and the New Model Army. Under the leadership of Oliver Cromwell they were victorious, executed Charles I of England and gained complete state power, establishing the Commonwealth of England between 1649 and 1660. The Philo-Semitic millennialist undercurrent came to have a direct influence on politics. A number of Cromwell's close advisors, such as John Dury, John Sadler and Hugh Peter, came into contact with Dutch-based Jews such as Menasseh ben Israel and advocated Jewish resettlement in England (they had been banned from the country since the 13th century). Sadler, Cromwell's secretary, even argued that the British were one of the Lost Tribes of Israel in his pamphlet The Rights of the Kingdom (1649) and thus kindred to the Jews, initiating British Israelism. Other Puritans such as Jeremiah Burroughs, Peter Bulkley, John Fenwicke and John Cotton, some of whom lived in the Massachusetts Bay Colony, saw Jewish re-entry to England as a step on the path to their eventual return to Palestine (all tied up within a millennialist eschatology, which would hasten the Second Coming of Jesus Christ and thus the final judgement). Johanna and Ebenezer Cartwright, two Baptists who had spent time in Amsterdam, held the same view and issued the original petition to Thomas Fairfax's Council of War in January 1649 for Jewish readmission: the petition hoped, "That this Nation of England, with the inhabitants of the Netherlands, shall be the first and the readiest to transport Israel's sons and daughters on their ships to the land promised to their forefathers, Abraham, Isaac, and Jacob for an everlasting inheritance." Their de facto toleration in England was informally achieved by 1655 to 1656 and was not rolled back after the Restoration.

A prominent French-born figure Isaac La Peyrère, who was nominally a Huguenot Calvinist, but came from a Portuguese New Christian (converted Sephardic Jewish) family was also a significant 17th century progenitor, with influence on both sides of the English Channel. La Peyrère in his millennialist work Du rappel des juifs (1643) wrote about a Jewish return to Palestine, predicted the building of the Third Temple and Jerusalem playing the most powerful role in world governance: all working towards the Second Coming. La Peyrère closely followed the developments of Oliver Cromwell's Dissenter regime and dreamed of overthrowing Louis XIV of France and replacing him with the Prince of Condé (who he worked for as a secretary) as part of a millennialist proto-Zionist messianic project. After the publication of La Peyrère's book the Amsterdam-based Menasseh Ben Israel informed his friend, Petrus Serrarius (a close associate of John Dury), about the importance of the theories, showing an early interplay between 17th century Jewish and Protestant proto-Zionism. Other Continental Protestant millennialists enthused by La Peyrère's theories were the Germans Abraham von Franckenberg (a student of the Kabbalah) and Paul Felgenhauer. Menasseh Ben Israel himself would author The Hope of Israel in 1652. Serrarius ended up being the main supporter among Protestants in Amsterdam of the message that Sabbatai Zevi was the Messiah, as proclaimed by Nathan of Gaza (his followers, the Sabbateans, were based in the Ottoman Empire but he had significant support throughout the Jewish diaspora).

Although removed from power in England itself, the millennialist Puritans who had moved to North America continued to have a deeper cultural legacy in society. As well as John Cotton, Increase Mather, one of the early Presidents of Harvard University was a strong proponent of the restoration of the Jews to Palestine. An author of numerous works, his most notable in this regard was The Mystery of Israel's Salvation (1669). Roger Williams, the Puritan proponent of religious liberty (including for Jews) in the Colony of Rhode Island that he founded has been citied as a proto-Zionist in speeches by later Jewish Zionist leaders such as Stephen S. Wise, due to his comment that "I have longed after some trading with the Jews themselves, for whose hard measure I fear the nations and England have yet a score to pay." Some important 17th-century philosophers who acted a bridge between the millennialist sectarians of their day and the approaching Age of the Enlightenment with its scientific revolution either held views associated with premillennial restorationists, or moved closely in their circles: this applies particularly to Sir Isaac Newton and Baruch Spinoza. Newton especially, who held Radical Reformation views in terms of religion and also dabbled in the occult (including the Kabbalah) predicted a Jewish return to Palestine, with the rebuilding of Jerusalem in the late 19th century and the erection of the Third Temple in the 20th or 21st century, leading to the end of the world no later than 2060. Much of these private writings were embarrassing to his supporters who sought to uphold him as a man of reason and science against Leibniz and while the University of Cambridge inherited his scientific papers, they refused to take these private ones. Many of these, collected by Abraham Yahuda, now rest in the National Library of Israel since 1967. Spinoza for his part, although Jewish himself, moved in circles in the Netherlands which included Petrus Serrarius, Henry Oldenburg and was even directly influenced by La Peyrère.

Pietism, Evangelicalism, and British foreign policy

With the rise of the Hanoverians to power in Britain and the ascent of the Enlightenment, much of the 18th century mainstream elite adopted Philhellenism, looking back to the culture and philosophies of classical world for inspiration for the Georgian age, rather than entertaining millennialist fantasies based on the Hebrew Old Testament (though Jews themselves enjoyed significant toleration in the British Empire). Although marginal at first, a religious underground was slowly growing from the 1730s which would eventually spout a second wave of Protestant Zionism and with it the birth of Evangelical Protestantism. This was precipitated in Germany by Philipp Spener's Pietism, a mystical and often millennialist take on Lutheranism, which prophesied the "conversion of the Jews and the fall of the Papacy as the prelude of the triumph of the Church." One of Spener's followers, Nicolaus Zinzendorf, spread this into the Moravian Church, linking the theory to Palestine, changing the Moravian liturgy to include a prayer "to restore the tribe of Judah in its time and bless its first fruits among us." John and Charles Wesley, early leaders in Methodism; inspired by the Pietists and Zinzendorf's Moravians; also promoted a Jewish return to Palestine with Charles Wesley even authoring a hymn dedicated to it. The Baptist, John Gill, who moved in similar circles to the Wesleys, authored works expressing similar views. By 1771, the Evangelical minister, John Eyre, founder of the Evangelical Magazine and among the original members of the London Missionary Society was promoting a more developed version of these views with his Observations upon Prophecies Relating to the Restoration of the Jews.

The Earl of Shaftesbury, influenced by Evangelical Anglicanism and the views of Edward Bickersteth was one of the first British politicians to seriously endorse a Jewish return to Ottoman Palestine as official policy.

By the end of the 18th century, in the aftermath of the French Revolution and the National Assembly decreeing in December 1789 that non-Catholics were eligible for all civil and military positions, the Revolutionary government in France made a play for the allegiance of Jews, in competition with Britain. During the Egypt–Syria campaign of the French Revolutionary Wars, Bonaparte invited "all the Jews of Asia and Africa to gather under his flag in order to re-establish the ancient Jerusalem." Although Bonaparte himself was secular and the idea an early example of pragmatic Political Zionism, the Jacobin idea itself may have originated from Thomas Corbet (1773-1804), an Anglo-Irish Protestant émigrée who, as a member of the liberal-republican Society of United Irishmen, was an ally of the Jacobin-government, engaged in revolutionary activities against the British and served in the French Army. In February 1790, he authored a letter to the French Directory, then under the leadership of Napoleon's patron Paul Barras. In the letter he stated "I recommend you, Napoleon, to call on the Jewish people to join your conquest in the East, to your mission to conquer the land of Israel" saying, "Their riches do not console them for their hardships. They await with impatience the epoch of their re-establishment as a nation." Dr. Milka Levy-Rubin, a curator at the National Library of Israel, has attributed Corbet's motivation to a Protestant Zionism based on premillennialist themes.

In British America and then the United States during the 18th century, Ezra Stiles, president of Yale University was a supporter of Jewish restoration and befriended Rabbi Raphael Chaim Yitzchak Karigal of Hebron in 1773 during his visit to the United States. Jonathan Edwards also anticipated a future return of Jews to their homeland. In 1808, Asa McFarland, a Presbyterian, voiced the opinion of many that the fall of the Ottoman Empire was imminent and would bring about Jewish restoration. One David Austin of New Haven spent his fortune building docks and inns from which the Jews could embark to the Holy Land. In 1825, Mordecai Manuel Noah, a Jew who wanted to found a national home for the Jews on Grand Island in New York as a way station on the way to the Holy Land, won widespread Christian backing for his project. Likewise, restorationist theology was among the inspirations for the first American missionary activity in the Middle East and for mapping the Holy Land.

Most early-19th-century British Restorationists, like Charles Simeon, were postmillennial in eschatology. With the rise of James Frere, James Haldane Stewart and Edward Irving a major shift in the 1820s towards premillennialism occurred, with a similar focus on advocacy for the restoration of the Jews to Israel. As the demise of the Ottoman Empire appeared to be approaching, the advocacy of restorationism increased. At the same time, the visit of John Nelson Darby, the founder of a variant of premillennialism called dispensationalism, to the United States catalyzed a new movement. This was expressed at the Niagara Bible Conference in 1878, which issued a 14-point proclamation (relying on Luke 12:35–40, 17:26–30, 18:8 Acts 15:14–17, 2 Thessalonians 2:3–8, 2 Timothy 3:1–5, and Titus 1:11–15), including:

that the Lord Jesus will come in person to introduce the millennial age, when Israel shall be restored to their own land, and the earth shall be full of the knowledge of the Lord; and that this personal and premillennial advent is the blessed hope set before us in the Gospel for which we should be constantly looking.

The dispensationalist theology of John Nelson Darby is often claimed to be a significant awakener of American Christian Zionism. He first distinguished the hopes of the Jews and that of the church and gentiles in a series of 11 evening lectures in Geneva in 1840. His lectures were immediately published in French (L'Attente Actuelle de l'Eglise), English (1841), German and Dutch (1847) and so his teachings began their global journey. Some dispensationalists, like Arno Gabelein, whilst philo-semitic, opposed Zionism as a movement born in self-confidence and unbelief. While dispensationalism had considerable influence through the Scofield Reference Bible, Christian lobbying for the restoration of the Jews preceded the publication of the Scofield Reference Bible (first published by OUP, 1909) by over a century, and many Christian Zionists and Christian Zionist organizations such as the International Christian Embassy Jerusalem do not subscribe to dispensationalism. Many non-dispensationalist Protestants were also strong advocates of a Jewish return to their homeland, Charles Spurgeon, both Horatius and Andrew Bonar, Robert Murray M'Chyene, and J. C. Ryle were among a number of proponents of both the importance and significance of a Jewish return to Israel. However Spurgeon averred of dispensationalism: "It is a mercy that these absurdities are revealed one at a time, in order that we may be able to endure their stupidity without dying of amazement". In 1864, Spurgeon wrote:

We look forward, then, for these two things. I am not going to theorize upon which of them will come first — whether they shall be restored first, and converted afterwards — or converted first and then restored. They are to be restored and they are to be converted, too.

The crumbling of the Ottoman Empire threatened the British route to India via the Suez Canal as well as sundry French, German and American economic interests. In 1831 the Ottomans were driven from Greater Syria (including Palestine) by an expansionist Egypt, in the First Turko-Egyptian War. Although Britain forced Muhammad Ali to withdraw to Egypt, the Levant was left for a brief time without a government. The ongoing weakness of the Ottoman Empire made some in the west consider the potential of a Jewish state in the Holy Land. A number of important figures within the British government advocated such a plan, including Charles Henry Churchill. Again during the lead-up to the Crimean War (1854), there was an opportunity for political rearrangements in the Near East. In July 1853, Anthony Ashley-Cooper, 7th Earl of Shaftesbury, who was President of the London Society for Promoting Christianity Amongst the Jews, wrote to Prime Minister Aberdeen urging Jewish restoration as a means of stabilizing the region.

Late-19th-century non-messianic restorationism was largely driven by concern over the fate of the Jews of the Russian Empire, beset by poverty and by deadly, government-inspired pogroms. It was widely accepted that western nations did not wish to receive Jewish immigrants. Restorationism was a way for charitable individuals to assist oppressed Jews without actually accepting them as neighbors and fellow-citizens. In this, Restorationism was not unlike the efforts of the American Colonization Society to send blacks to Liberia and the efforts of British abolitionists to create Sierra Leone. Winston Churchill endorsed Restoration because he recognized that Jews fleeing Russian pogroms required a refuge, and preferred Palestine for sentimental reasons.

In the United States

In 1818, President John Adams wrote, "I really wish the Jews again in Judea an independent nation", and believed that they would gradually become Unitarian Christians.

In 1844, George Bush, a professor of Hebrew at New York University and the cousin of an ancestor of the Presidents Bush, published a book titled The Valley of Vision; or, The Dry Bones of Israel Revived. In it he denounced "the thralldom and oppression which has so long ground them (the Jews) to the dust," and called for "elevating" the Jews "to a rank of honorable repute among the nations of the earth" by allowing restoring the Jews to the land of Israel where the bulk would be converted to Christianity. This, according to Bush, would benefit not only the Jews, but all of mankind, forming a "link of communication" between humanity and God. "It will blaze in notoriety ...". "It will flash a splendid demonstration upon all kindreds and tongues of the truth."

Herman Melville expressed the idea in a poem, "Clarel; A Poem and Pilgrimage in the Holy Land":

the Hebrew seers announce in time
the return of Judah to her prime;
Some Christians deemed it then at hand
Here was an object. Up and On.
With seed and tillage help renew –
Help reinstate the Holy Land

The tycoon William Eugene Blackstone was inspired by the conference to publish the book Jesus is Coming, which took up the restorationist cause. His book was translated and published in Yiddish. On November 24–25, 1890, Blackstone organized the Conference on the Past, Present and Future of Israel at the First Methodist Episcopal Church in Chicago where participants included leaders of many Christian communities. Resolutions of sympathy for the oppressed Jews living in Russia were passed, but Blackstone was convinced that such resolutions—even though passed by prominent men—were insufficient. He advocated strongly for the resettlement of Jewish people in Palestine. In 1891 he lobbied President Benjamin Harrison for the restoration of the Jews, in a petition signed by 413 prominent Americans, that became known as the Blackstone Memorial. The names included the US Chief Justice, Speaker of the House of Representatives, the Chair of the House Foreign Relations Committee, and several other congressmen, Rockefeller, Morgan and famous industrialists. It read, in part: "Why shall not the powers which under the treaty of Berlin, in 1878, gave Bulgaria to the Bulgarians and Servia to the Servians now give Palestine back to the Jews? ... These provinces, as well as Romania, Montenegro, and Greece, were wrested from the Turks and given to their natural owners. Does not Palestine as rightfully belong to the Jews?"

In the British Empire

By the time of Mandate Palestine, the British struggled to balance sympathies for Jews and Arabs. Some, such as Orde Wingate, fought alongside the Haganah as part of the Special Night Squads.

Ideas favoring the restoration of the Jews in Palestine or the Land of Israel entered the British public discourse in the 1830s, though British Reformationists had written about the restoration of the Jews as early as the 16th century, and the idea had strong support among Puritans. Not all such attitudes were favorable towards the Jews; they were shaped in part by a variety of Protestant beliefs, or by a streak of philo-Semitism among the classically educated British elite, or by hopes to extend the Empire.

At the urging of Lord Shaftesbury, Britain established a consulate in Jerusalem in 1838, the first diplomatic appointment to Palestine.

In 1839, the Church of Scotland sent Andrew Bonar, Robert Murray M'Cheyne, Alexander Black and Alexander Keith on a mission to report on the condition of the Jews in Palestine. Their report was widely published. They traveled through France, Greece, and Egypt, and from Egypt, overland to Gaza. On the way home they visited Syria, the Austrian Empire and some of the German principalities. They sought out Jewish communities and inquired about their readiness to accept Christ, and separately, their preparedness to return to Israel as prophesied in the Bible. Alexander Keith recounted the journey in his 1844 book The Land of Israel According to the Covenant with Abraham, with Isaac, and with Jacob. It was also in that book that Keith used the slogan that became popular with other Christian Restorationists, a land without a people for a people without a land. In 1844 he revisited Palestine with his son, George Skene Keith (1819–1910), who was the first person to photograph the land.

An important, though often neglected, figure in British support of the restoration of the Jews was William Hechler (1845–1931), an English clergyman of German descent who was Chaplain of the British Embassy in Vienna and became a close friend of Theodor Herzl. Hechler was instrumental in aiding Herzl through his diplomatic activities, and may, in that sense, be called the founder of modern Christian Zionism. When it came to mark the twenty-fifth anniversary of Herzl's death, it was noted by the editors of the English-language memorial volume that William Hechler would prove "not only the first, but the most constant and the most indefatigable of Herzl’s followers".

On 2 November 1917, UK Home Secretary Arthur Balfour sent a letter to Lord Walter Rothschild. This letter, which would come to be known as the Balfour Declaration, famously stated that "His Majesty's Government view with favour the establishment in Palestine of a national home for the Jewish people." As noted by Philip Alexander, "A crucial ingredient in Balfour's Zionism [may have been] his Christian belief or, to put it a little more subtly, his Christian formation. The most persuasive advocate of this thesis is the Canadian historian Donald Lewis in his 2010 monograph, The Origins of Christian Zionism, but it has been espoused by a number of other scholars as well."

Between World War I and the 1948 Palestine War

Martin Luther King Jr. was a notable Christian supporter of Israel and Zionism.

In the United States

In the decades leading up to the establishment of Israel in 1948, the most prominent and politically active American Christian supporters of Zionism were liberal and mainline Protestants whose support for the movement was often unrelated to their interpretation of the Bible. These Christian supporters of Zionism viewed Palestine as a needed safe haven for Jews who were fleeing from intensifying persecution in Europe and they frequently believed that their support of the movement was part of a broader effort at interfaith rapprochement. The Pro-Palestine Federation, a Christian pro-Zionist organization which was founded in 1930, called for the promotion of “goodwill and esteem between Jews and non-Jews” and it also called for the British government to adhere to the terms of its Mandate for Palestine, which pledged support for the establishment of a Jewish national home.

Amidst World War II and their growing awareness of the Holocaust, American Jewish Zionists helped coordinate the establishment of two non-Jewish Zionist organizations, the American Palestine Committee and the Christian Council on Palestine, which were later merged into the American Christian Palestine Committee (ACPC). The ACPC, which was composed largely of liberal and mainline Protestants, became the leading American Christian lobby in support of the creation of a Jewish state in Palestine. After the establishment of Israel in 1948, the ACPC continued its lobbying efforts. For instance, it coordinated opposition to the United Nations’ efforts to internationalize the city of Jerusalem, which was divided between Israel and Transjordan in the 1948 War.

During these years, premillennialism (including its dispensationalist variety) grew in popularity among conservative American Protestants. Many premillennialists viewed the Zionist movement as at least a partial fulfillment of biblical prophecy or they viewed it as a modern fulfillment of God's covenantal promises to the Jewish people. In the 1930s, Southern Baptist missionary Jacob Gartenhaus, himself a convert from Judaism, argued that “Zionism is going to win whether anybody likes it or not...To oppose it is to oppose God’s plan.” But for the most part, such beliefs did not translate into political action on behalf of the movement in this era. One slight exception was J. Frank Norris, a fundamentalist Baptist who split time between pulpits in Fort Worth, Texas, and Detroit, Michigan. While Norris did not organize lobbying efforts in the way that the ACPC did, he did preach to his followers that it was their Christian duty to support the Zionist cause and wrote President Truman in support of Zionist claims to Palestine in 1947 and 1948. Norris also loosely coordinated with the ACPC, at times publishing their materials in his periodical, The Fundamentalist.

After the founding of the State of Israel

The Flag of Israel, flying alongside the Union Flag and the Ulster Banner. In the Protestant Unionist community of Northern Ireland, sympathy for Israel is frequently expressed by communal flag-flying.

In the United States

In the decades since the establishment of Israel, and especially since the 1967 Six-Day War, the most prominent American Christian supporters of Israel have come from the evangelical wing of American Protestantism. American evangelicalism itself underwent significant changes in the years surrounding Israel's birth, as a "new" evangelicalism led by figures like Billy Graham emerged from Protestantism and came to cultural prominence. It was among these new evangelicals that the contemporary movement that most commonly associated with the term "Christian Zionism" originated.

Many new evangelicals adhered to dispensationalism or at least, they adhered to beliefs which were inspired by it—most especially, they adhered to the dispensationalist understanding that Jews remained in a special covenantal relationship with God. Most important to the development of Christian Zionism as a movement, though, was the fact that American evangelical leaders began to build relationships with American and Israeli Jews and they also began to build institutional connections with Jewish organizations and the Israeli government itself. Crucial to the building of these relationships was a motivated coterie of American evangelicals who resided in Israel, most notably, the founder of the American Institute of Holy Land Studies, G. Douglas Young. Through his institute, Young worked to convince American Christians that it was their biblical duty to support the Jewish people and the Jewish state. He also worked as a go-between for Jewish organizations and Israeli government agencies which were seeking to build relationships with American evangelicals. Such activism provided the basis for the development of Christian Zionism as a movement.

Such activism, it should be noted, was in many ways distinct from the prophetic speculation about the State of Israel that exploded after the 1967 Six-Day War (even as it had somewhat common theological and hermeneutical antecedents). This activism includes the wildly popular writings of the American dispensationalist evangelical writer Hal Lindsey, which sought to fit Israel into a dispensationalist end-time narrative. In The Late Great Planet Earth, for example, Lindsey anticipated that, per Ezekiel 39:6–8, Jews would fight off a "Russian" invasion before realizing their miraculous deliverance and converting to Christianity. Their lives would be spared the great fire that God will put upon Russia and people of the "coastlands." And, per Zechariah 13:8–9, one third of Jews alive who have converted will be spared. Lindsay has been critiqued for highly specific, failed predictions even by those who share his eschatology, like John MacArthur.

Examples of Protestant leaders who combined political conservatism with Christian Zionism are Jerry Falwell and Pat Robertson, leading figures on the Christian Right in the 1980s and 1990s. In 1981, Falwell said: "To stand against Israel is to stand against God. We believe that history and scripture prove that God deals with nations in relation to how they deal with Israel." They cite part of the blessing of Isaac at Genesis 27:29, "Those who curse you will be cursed, and those who bless you will be blessed." Martin Luther King Jr. has also been cited as a Christian supporter of Israel and Zionism.

In Israel

The government of Israel has given official encouragement to Christian Zionism, allowing the establishment of the International Christian Embassy Jerusalem in 1980. The embassy has raised funds to help finance Jewish immigration to Israel from the former Soviet Union, and has assisted Zionist groups in establishing Jewish settlements in the West Bank.

The Third International Christian Zionist Congress, held in Jerusalem in February 1996, issued a proclamation which said:

God the Father, Almighty, chose the ancient nation and people of Israel, the descendants of Abraham, Isaac and Jacob, to reveal His plan of redemption for the world. They remain elect of God, and without the Jewish nation His redemptive purposes for the world will not be completed.

Jesus of Nazareth is the Messiah and has promised to return to Jerusalem, to Israel and to the world.

It is reprehensible that generations of Jewish peoples have been killed and persecuted in the name of our Lord, and we challenge the Church to repent of any sins of commission or omission against them.

The modern Ingathering of the Jewish People to Eretz Israel and the rebirth of the nation of Israel are in fulfilment of biblical prophecies, as written in both Old and New Testaments.

Christian believers are instructed by Scripture to acknowledge the Hebraic roots of their faith and to actively assist and participate in the plan of God for the Ingathering of the Jewish People and the Restoration of the nation of Israel in our day.

Popular interest in Christian Zionism was given a boost around the year 2000 in the form of the Left Behind series of novels by Tim LaHaye and Jerry B. Jenkins. The novels are built around the prophetic role of Israel in the apocalyptic end times.

Critical views within Christianity

General

For most Christians the City of God (Psalm 46:4 (Septuagint: ΜΕ:5): "ἡ πόλις τοῦ Θεοῦ", romanized: "hē pólis toũ theoũ", lit.'the city of God') has nothing to do with Jewish immigration to Israel and the ongoing Israeli–Palestinian conflict, instead, it predicts the sack of Rome (410) and it is cited in the teaching of Saint Augustine of Hippo, whose rejection of millennialism was adopted by the Council of Ephesus (431). That is why neither Eastern Orthodox Christians nor traditional Catholic Christians did consider Zionism in any political form: "[T]he Eastern Orthodox Church [...] upheld a historic lack of emphasis on pilgrimage, insisting that the land of promise was not Palestine but the Kingdom of God. Thus, Patriarch Ignatius IV, head of the church in the Middle East, reiterated that the people were his concern in Jerusalem, not the stones." Not a worldly kingdom, not an earthly Jerusalem is sought after, but the focus is on the heavenly Jerusalem, the kingdom of the triune God:

At first you will see prayer as a ladder, then as a book which you read, and finally, as you advance further and further, you will see it as the heavenly Jerusalem, the city of the King of Hosts, Who is together with His Fatherwith Whom He is of one Essenceand with the venerable Holy Spirit.

Catholic Church

Theodor Herzl had an audience with Pope Pius X in 1904. The Pope explained that the Catholic Church could not theologically endorse Zionism and control of Holy Places in Jerusalem.

The Catholic Church—the largest branch of Christians in the world—does not endorse the theological premises underlying millennialist Protestant Restorationism and has generally inveighed against the prospect of Jewish governance over Holy Places in Palestine which it deems of importance to Christianity. Theodor Herzl, the secular Jewish founder of modern political Zionism, had an audience in the Vatican with Pope Pius X in 1904, arranged by the Austrian Count Berthold Dominik Lippay, seeking out the position of the Catholic Church on Herzl's prospective project for a Jewish state in Palestine. Pope Pius X stated "We cannot prevent the Jews from going to Jerusalem—but we could never sanction it. The soil of Jerusalem, if it was not always sacred, has been sanctified by the life of Jesus Christ. As the head of the Church I cannot tell you anything different. The Jews have not recognized our Lord, therefore we cannot recognize the Jewish people." After Herzl explained that his reasoning behind the project for the creation of a Jewish state was not a religious statement, but interest in secular land for national independence, Pope Pius X replied "Does it have to be Gerusalemme?"

While rejecting a theological basis for Zionism outright, a major concern for the Holy See was the Holy Places associated with Jesus Christ falling under the governance of such a state. By the mid-19th century, relations between the Vatican and Istanbul were fairly collegial; the Muslim Ottomans by that time permitted the Vatican to work among the Arab Catholics in Palestine and access the Holy Places quite freely and so the status quo was already workable for them. Following the United Nations Partition Plan for Palestine, the Vatican advocated Jerusalem being a separate "international city", as laid out in the encyclical Redemptoris nostri cruciatus. Until the Second Vatican Council, the Catholic Church was forthright in lobbying against Zionism internationally (including the Catholic Church in the United States, as the United States had become Zionism's most powerful endorser). The State of Israel and the Holy See only established full diplomatic relations in 1993 and this was a recognition of political and civic reality, not a theological statement.

Protestantism

Political Zionism, which "came down like the wolf on the fold", has also been anathematized by eminent Protestants:

[I]t is the conviction of most biblical scholars that the Old Testament contains no description of the restoration of Israel to its ancient homeland which can apply to the Jewish people of the present age.

— The Christian Century: 144–145. December 1929

Political Zionism and Christian Zionism are biblically anathema to the Christian faith. [...] [T]rue Israel today is neither Jews nor Israelis, but believers in the Messiah, even if they are gentiles.

In the United States, the General Assembly of the National Council of Churches in November 2007 approved a resolution for further study which stated that the "theological stance of Christian Zionism adversely affects:

  • justice and peace in the Middle East, delaying the day when Israelis and Palestinians can live within secure borders
  • relationships with Middle Eastern Christians (see the Jerusalem Declaration on Christian Zionism)
  • relationships with Jews, since Jews are seen as mere pawns in an eschatological scheme
  • relationships with Muslims, since it treats the rights of Muslims as subordinate to the rights of Jews
  • interfaith dialogue, since it views the world in starkly dichotomous terms"

The Reformed Church in America at its 2004 General Synod found "the ideology of Christian Zionism and the extreme form of dispensationalism that undergirds it to be a distortion of the biblical message noting the impediment it represents to achieving a just peace in Israel/Palestine." The Mennonite Church published an article that described the ongoing seizure of additional Palestinian lands by Israeli militants as illegal, noting that in some churches under the influence of Christian Zionism the "congregations 'adopt' illegal Israeli settlements, sending funds to bolster the defense of these armed colonies." As of September 2007, churches in the USA that have criticized Christian Zionism include the United Methodist Church, the Presbyterian Church (USA), and the United Church of Christ.

The film With God On Our Side, by Porter Speakman Jr. and Kevin Miller (the latter of whom also co-created the film Expelled: No Intelligence Allowed), criticizes both the underlying theology behind Christian Zionism as well as its negative influence on the church.

In the United Kingdom, the Church of Scotland, despite its Restorationist history, has recently been critical of Zionism in general, and in turn has received strong criticism over the perceived injustice of its report, "The Inheritance of Abraham: A Report on the Promised Land", which resulted in its republication in a briefer form. On 9 July 2012, the Anglican General Synod passed a motion affirming support for the Ecumenical Accompaniment Programme in Palestine and Israel (EAPPI). This was criticised by the Board of Deputies claiming the Synod 'has chosen to promote an inflammatory and partisan programme'. The advocated group was simultaneously criticised for its publication of a call for sit-ins at Israeli Embassies, the hacking of government websites to promote its message, and support for the Boycott, Divestment and Sanctions campaign against Israel.

Biblical interpretations

Some Christian Zionists interpret the prophetic texts as describing inevitable future events, and these events primarily involve Israel (taken to mean the descendants of the Biblical patriarch Jacob) or Judah (taken to mean the remaining faithful adherents of Judaism). These prophecies are seen as requiring the presence of a Jewish state in the Holy Land, the central part of the lands promised to the Biblical patriarch Abraham in the Covenant of the pieces. This requirement is sometimes interpreted as being fulfilled by the contemporary state of Israel.

Other doctrines

Christian schools of doctrine which consider other teachings to counterbalance these doctrines, or which interpret them in terms of distinct eschatological theories, are less conducive to Christian Zionism. Among the many texts which address this subject in counterbalance are the words of Jesus, as for example in Matthew 21:43, "the kingdom of God will be taken away from you and given to a nation producing the fruits of it".

In Defending Christian Zionism, David Pawson, a Christian Zionist in the United Kingdom, puts forward the case that the return of the Jews to the Holy Land is a fulfilment of scriptural prophecy, and that Christians should support the existence of the Jewish State (although not unconditionally its actions) on theological grounds. He also argues that prophecies spoken about Israel relate specifically to Israel (not to the church, as in "replacement theology"). However, he criticises Dispensationalism, which he says is a largely American movement holding similar views. Pawson was spurred to write this book by the work of Stephen Sizer, an evangelical Christian who rejects Christian Zionism.

Public opinion

A 2017 LifeWay poll conducted in United States found that 80% of evangelical Christians believed that the creation of Israel in 1948 was a fulfillment of biblical prophecy that would bring about Christ's return and more than 50% of Evangelical Christians believed that they support Israel because it is important for fulfilling the prophecy.

According to the Pew Research survey in 2003, more than 60% of the Evangelical Christians and about 50% of Blacks agreed that the existence of Israel fulfilled biblical prophecy. About 55% of poll respondents said that the Bible was the biggest influence for supporting Israel which is 11 times the people who said church was the biggest influence.

Co-sleeping

From Wikipedia, the free encyclopedia
A family together in a bed

Co-sleeping or bed sharing is a practice in which babies and young children sleep close to one or both parents, as opposed to in a separate room. Co-sleeping individuals sleep in sensory proximity to one another, where the individual senses the presence of others. This sensory proximity can either be triggered by touch, smell, taste, or noise. Therefore, the individuals can be a few centimeters away or on the other side of the room and still have an effect on the other. It is standard practice in many parts of the world, and is practiced by a significant minority in countries where cribs are also used.

Bed-sharing, a practice in which babies and young children sleep in the same bed with one or both parents, is a subset of co-sleeping. Co-bedding refers to infants (typically twins or higher-order multiples) sharing the same bed.

The American Academy of Pediatrics does encourage room-sharing (sleeping in the same room but on separate surfaces) in its policy statement regarding SIDS prevention, but it recommends against bed-sharing with infants.

Recent legal rulings suggest that bed-sharing has been attributed as a factor of unintentional infant suffocation. For instance, parents under the influence of drugs or alcohol and whose children died while bed-sharing have been charged and, at times, prosecuted with manslaughter in several US states (including Minnesota, Michigan, Georgia, Pennsylvania, Texas, Wisconsin and Utah).

Introduction

Bed-sharing among married couples is standard practice in many parts of the world outside of North America, Europe and Australia, and even in the latter areas a significant minority of children have shared a bed with their parents at some point in childhood. One 2006 study of children age 3–10 in India reported 93% of children bed-sharing while a 2006 study of children in Kentucky in the United States reported 15% of infants and toddlers 2 weeks to 2 years engage in bed-sharing.

Bed-sharing was widely practiced in all areas up to the 19th century, until the advent of giving the child his or her own room and the crib. In many parts of the world, bed-sharing simply has the practical benefit of keeping the child warm at night. Bed-sharing has been relatively recently re-introduced into Western culture by practitioners of attachment parenting. Proponents hold that bed-sharing saves babies' lives (especially in conjunction with nursing),  promotes bonding, enables the parents to get more sleep and facilitates breastfeeding. Older babies can breastfeed during the night without waking their mother. Opponents argue that co-sleeping is stressful for the child when they are not co-sleeping. They also cite concerns that a parent may smother the child or promote an unhealthy dependence of the child on the parent(s).

Because children become accustomed to behaviors learned in early experiences, bed-sharing in infancy will also increase the likelihood of these children to crawl into their parent's bed in ages past infancy.

Health and safety

Health care professionals disagree about bed-sharing techniques, effectiveness and ethics. The U.S. Consumer Product Safety Commission and the American Academy of Pediatrics strongly discourage bed-sharing because of the risk of suffocation or strangulation, but some pediatricians and breast-feeding advocates have opposed this position.

Known risks

There are certain dangerous behaviors that increase SIDS and should be avoided whether placing a baby in a crib or co-sleeping: infants should always sleep on their backs on a firm surface (not waterbeds, pillows, recliners, or couches), mattresses should intersect the bedframe tightly, there should be no stuffed animals or soft toys near the baby, blankets should be light, a baby's head should never be covered, and other SIDS risk factors should be avoided. In addition some parents pose threats to infants due to their behaviors and conditions, such as smoking or drinking heavily, taking drugs, a history of skin infections, obesity, or any other specific risk-increasing traits.

Co-sleeping also increases the risks of suffocation and strangulation. The soft quality of the mattresses, comforters, and pillows may suffocate the infants. Some experts, then, recommend that the bed should be firm, and should not be a waterbed or couch; and that heavy quilts, comforters, and pillows should not be used. Another common advice given to prevent suffocation is to keep a baby on its back, not its stomach. Parents who roll over during their sleep could inadvertently crush and/or suffocate their child, especially if they are heavy sleepers, over-tired or over-exhausted and/or obese. There is also the risk of the baby falling to a hard floor, or getting wedged between the bed and the wall or headboard. A proposed solution to these problems is the bedside bassinet, in which, rather than bed-sharing, the baby's bed is placed next to the parent's bed.

The presence of the child in the parent's bedroom also raises the concern of a lack of privacy between the parents and the child. The lack of privacy may result in increased tension and reduced intimacy between a couple.

Another precaution recommended by experts is that young children should never sleep next to babies under nine months of age.

A 2008 report explored the relationship between ad hoc parental behaviors similar to traditional co-sleeping methodology, though the study's subjects typically utilized cribs and other paraphernalia counter to co-sleeping models. While babies who had been exposed to behaviors reminiscent of co-sleeping had significant problems with sleep later in life, the study concluded that the parental behaviors were a reaction to already-present sleep difficulties. Most relationships between parental behavior and sleeping trouble were not statistically significant when controlled for those preexisting conditions. Further, typical co-sleeping parental behavior, like maternal presence at onset of sleep, were found to be protective factors against sleep problems.

Association with sudden infant death syndrome (SIDS)

Co-sleeping can often be regarded as an unnecessary practice that can be associated with issues such as sudden infant death syndrome (SIDS). However, research shows that opinions vary in the association between SIDS and co-sleeping. The most controversial issue regarding SIDS is whether bed sharing is a main cause, and whether it should be avoided or encouraged.

Research indicates that co-sleeping, particularly bed sharing should be avoided as it increases the risk of SIDS. Controversially, research shows that if co-sleeping practices are done in an appropriate and safe manner it can be very beneficial and reduce risk of SIDS occurring. The Pacific Islands Families study, conducted in New Zealand, showed that the adoption of safe bed-sharing and room-sharing practices were saving infant lives and that there was no infant that died from SIDS.

Arguments In favor

One study reported mothers getting more sleep and breast-feeding by co-sleeping than other arrangements. Parents also experience less exhaustion with such ease in feeding and comforting their child by simply reaching over to the child. As a result, co-sleeping also increases the responsiveness of parents to their child's needs.

It has been argued that co-sleeping evolved over five million years, that it alters the infant's sleep experience and the number of maternal inspections of the infant, and that it provides a beginning point for considering possibly unconventional ways of helping reduce the risk of sudden infant death syndrome (SIDS).

Stress hormones are lower in mothers and babies who co-sleep, specifically the balance of the stress hormone cortisol, the control of which is essential for a baby's healthy growth. In studies with animals, infants who stayed close to their mothers had higher levels of growth hormones and enzymes necessary for brain and heart growth. Also, the physiology of co-sleeping babies is more stable, including more stable temperatures, more regular heart rhythms, and fewer long pauses in breathing than babies who sleep alone.

Besides physical developmental advantages, co-sleeping may also promote long-term emotional health. In long-term follow-up studies of infants who slept with their parents and those who slept alone, the children who co-slept were happier, less anxious, had higher self-esteem, were less likely to be afraid of sleep, had fewer behavioral problems, tended to be more comfortable with intimacy, and were generally more independent as adults.

Products for infants

There are several products that claim they can be used to facilitate safe co-sleeping with an infant however these claims are not evidence based:

  • special-purpose bedside bassinets, sidecar sleepers and bedside sleepers, which attach directly to the side of an adult bed and are open to the parent's side, but have barriers on the other three sides.
  • bed top co-sleeping products designed to prevent the baby from rolling off the adult bed and to absorb breastmilk and other nighttime leaks.
  • side rails to prevent the child from rolling off the adult bed.
  • co-sleeping infant enclosures which are placed directly in the adult bed.
  • specially designed separate sleeping bags for parents and infants which prevent covers being inadvertently pulled over the baby's head.
  • wahakura : A simple woven basket that allows babies to safely sleep in the same bed as parents.

Prevalence

A study of a small population in Northeast England showed a variety of nighttime parenting strategies and that 65% of the sample had bed-shared, 95% of them having done so with both parents. The study reported that some of the parents found bedsharing effective, yet were covert in their practices, fearing disapproval of health professionals and relatives. A National Center for Health Statistics survey from 1991 to 1999 found that 25% of American families always, or almost always, slept with their baby in bed, 42% slept with their baby sometimes, and 32% never bed-shared with their baby.

Chinese

Due to Chinese high rents and housing and unemployement crisis in an common co-rental "bedmates" arrangement approach some people shared the same room/bed with strangers.

Factors

Socioeconomic factors

Initial assumptions on co-sleeping may place it in a context of income and socioeconomic status. Generally, families of low socioeconomic status will be unable to afford a separate room for a child while those of high socioeconomic status can more easily afford a home with a sufficient number of rooms. However, statistical data shows the prevalence of co-sleeping in wealthy Japanese families and the ability of poor Western families to still find a separate space for their child, suggests that the acceptance of co-sleeping is a result of culture.

Cultural factors

Several studies show that the prevalence of co-sleeping is a result of cultural preference. In a study of 19 nations, a trend emerged, depicting a widely accepted practice of co-sleeping in Asian, African, and Latin American countries, while European and North American countries rarely practiced it. This trend resulted mostly from the respective fears of parents: Asian, African, and Latin American parents worried about the separation between the parents and the child, while European and North American parents feared a lack of privacy for both the parents and the child.

Orbital maneuver

From Wikipedia, the free encyclopedia

In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a deep-space maneuver (DSM).

The rest of the flight, especially in a transfer orbit, is called coasting.

General

Rocket equation

Rocket mass ratios versus final velocity calculated from the rocket equation

The Tsiolkovsky rocket equation, or ideal rocket equation is an equation that is useful for considering vehicles that follow the basic principle of a rocket: where a device that can apply acceleration to itself (a thrust) by expelling part of its mass with high speed and moving due to the conservation of momentum. Specifically, it is a mathematical equation that relates the delta-v (the maximum change of speed of the rocket if no other external forces act) with the effective exhaust velocity and the initial and final mass of a rocket (or other reaction engine.)

For any such maneuver (or journey involving a number of such maneuvers):

where:

is the initial total mass, including propellant,
is the final total mass,
is the effective exhaust velocity ( where is the specific impulse expressed as a time period and is standard gravity),
is delta-v - the maximum change of velocity of the vehicle (with no external forces acting).

Delta-v

The applied change in velocity of each maneuver is referred to as delta-v ().

The delta-v for all the expected maneuvers are estimated for a mission. They are summarized in a delta-v budget. With a good approximation of the delta-v budget designers can estimate the fuel to payload requirements of the spacecraft using the rocket equation.

Impulsive maneuvers

Figure 1: Approximation of a finite thrust maneuver with an impulsive change in velocity

An "impulsive maneuver" is the mathematical model of a maneuver as an instantaneous change in the spacecraft's velocity (magnitude and/or direction) as illustrated in figure 1. It is the limit case of a burn to generate a particular amount of delta-v, as the burn time tends to zero.

In the physical world no truly instantaneous change in velocity is possible as this would require an "infinite force" applied during an "infinitely short time" but as a mathematical model it in most cases describes the effect of a maneuver on the orbit very well.

The off-set of the velocity vector after the end of real burn from the velocity vector at the same time resulting from the theoretical impulsive maneuver is only caused by the difference in gravitational force along the two paths (red and black in figure 1) which in general is small.

In the planning phase of space missions designers will first approximate their intended orbital changes using impulsive maneuvers that greatly reduces the complexity of finding the correct orbital transitions.

Low thrust for a long time

Applying a low thrust over a longer period of time is referred to as a non-impulsive maneuver. 'Non-impulsive' refers to the momentum changing slowly over a long time, as in electrically powered spacecraft propulsion, rather than by a short impulse.

Another term is finite burn, where the word "finite" is used to mean "non-zero", or practically, again: over a longer period.

For a few space missions, such as those including a space rendezvous, high fidelity models of the trajectories are required to meet the mission goals. Calculating a "finite" burn requires a detailed model of the spacecraft and its thrusters. The most important of details include: mass, center of mass, moment of inertia, thruster positions, thrust vectors, thrust curves, specific impulse, thrust centroid offsets, and fuel consumption.

Assists

Oberth effect

In astronautics, the Oberth effect is where the use of a rocket engine when travelling at high speed generates much more useful energy than one at low speed. Oberth effect occurs because the propellant has more usable energy (due to its kinetic energy on top of its chemical potential energy) and it turns out that the vehicle is able to employ this kinetic energy to generate more mechanical power. It is named after Hermann Oberth, the Austro-Hungarian-born, German physicist and a founder of modern rocketry, who apparently first described the effect.

The Oberth effect is used in a powered flyby or Oberth maneuver where the application of an impulse, typically from the use of a rocket engine, close to a gravitational body (where the gravity potential is low, and the speed is high) can give much more change in kinetic energy and final speed (i.e. higher specific energy) than the same impulse applied further from the body for the same initial orbit.

Since the Oberth maneuver happens in a very limited time (while still at low altitude), to generate a high impulse the engine necessarily needs to achieve high thrust (impulse is by definition the time multiplied by thrust). Thus the Oberth effect is far less useful for low-thrust engines, such as ion thrusters.

Historically, a lack of understanding of this effect led investigators to conclude that interplanetary travel would require completely impractical amounts of propellant, as without it, enormous amounts of energy are needed.

Gravitational assist

The trajectories that enabled NASA's twin Voyager spacecraft to tour the four gas giant planets and achieve velocity to escape our solar system

In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement and gravity of a planet or other celestial body to alter the path and speed of a spacecraft, typically in order to save propellant, time, and expense. Gravity assistance can be used to accelerate, decelerate and/or re-direct the path of a spacecraft.

The "assist" is provided by the motion (orbital angular momentum) of the gravitating body as it pulls on the spacecraft. The technique was first proposed as a mid-course manoeuvre in 1961, and used by interplanetary probes from Mariner 10 onwards, including the two Voyager probes' notable fly-bys of Jupiter and Saturn.

Transfer orbits

Orbit insertion is a general term for a maneuver that is more than a small correction. It may be used for a maneuver to change a transfer orbit or an ascent orbit into a stable one, but also to change a stable orbit into a descent: descent orbit insertion. Also the term orbit injection is used, especially for changing a stable orbit into a transfer orbit, e.g. trans-lunar injection (TLI), trans-Mars injection (TMI) and trans-Earth injection (TEI).

Hohmann transfer

Hohmann Transfer Orbit

In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits of different altitudes, in the same plane.

The orbital maneuver to perform the Hohmann transfer uses two engine impulses which move a spacecraft onto and off the transfer orbit. This maneuver was named after Walter Hohmann, the German scientist who published a description of it in his 1925 book Die Erreichbarkeit der Himmelskörper (The Accessibility of Celestial Bodies). Hohmann was influenced in part by the German science fiction author Kurd Laßwitz and his 1897 book Two Planets.

Bi-elliptic transfer

Bi-elliptic transfer from blue to red circular orbit

In astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer maneuver.

The bi-elliptic transfer consists of two half elliptic orbits. From the initial orbit, a delta-v is applied boosting the spacecraft into the first transfer orbit with an apoapsis at some point away from the central body. At this point, a second delta-v is applied sending the spacecraft into the second elliptical orbit with periapsis at the radius of the final desired orbit, where a third delta-v is performed, injecting the spacecraft into the desired orbit.

While they require one more engine burn than a Hohmann transfer and generally requires a greater travel time, some bi-elliptic transfers require a lower amount of total delta-v than a Hohmann transfer when the ratio of final to initial semi-major axis is 11.94 or greater, depending on the intermediate semi-major axis chosen.

The idea of the bi-elliptical transfer trajectory was first published by Ary Sternfeld in 1934.

Low energy transfer

A low energy transfer, or low energy trajectory, is a route in space which allows spacecraft to change orbits using very little fuel. These routes work in the Earth-Moon system and also in other systems, such as traveling between the satellites of Jupiter. The drawback of such trajectories is that they take much longer to complete than higher energy (more fuel) transfers such as Hohmann transfer orbits.

Low energy transfer are also known as weak stability boundary trajectories, or ballistic capture trajectories.

Low energy transfers follow special pathways in space, sometimes referred to as the Interplanetary Transport Network. Following these pathways allows for long distances to be traversed for little expenditure of delta-v.

Orbital inclination change

Orbital inclination change is an orbital maneuver aimed at changing the inclination of an orbiting body's orbit. This maneuver is also known as an orbital plane change as the plane of the orbit is tipped. This maneuver requires a change in the orbital velocity vector (delta v) at the orbital nodes (i.e. the point where the initial and desired orbits intersect, the line of orbital nodes is defined by the intersection of the two orbital planes).

In general, inclination changes can require a great deal of delta-v to perform, and most mission planners try to avoid them whenever possible to conserve fuel. This is typically achieved by launching a spacecraft directly into the desired inclination, or as close to it as possible so as to minimize any inclination change required over the duration of the spacecraft life.

Maximum efficiency of inclination change is achieved at apoapsis, (or apogee), where orbital velocity is the lowest. In some cases, it may require less total delta v to raise the spacecraft into a higher orbit, change the orbit plane at the higher apogee, and then lower the spacecraft to its original altitude.

Constant-thrust trajectory

Constant-thrust and constant-acceleration trajectories involve the spacecraft firing its engine in a prolonged constant burn. In the limiting case where the vehicle acceleration is high compared to the local gravitational acceleration, the spacecraft points straight toward the target (accounting for target motion), and remains accelerating constantly under high thrust until it reaches its target. In this high-thrust case, the trajectory approaches a straight line. If it is required that the spacecraft rendezvous with the target, rather than performing a flyby, then the spacecraft must flip its orientation halfway through the journey, and decelerate the rest of the way.

In the constant-thrust trajectory, the vehicle's acceleration increases during thrusting period, since the fuel use means the vehicle mass decreases. If, instead of constant thrust, the vehicle has constant acceleration, the engine thrust must decrease during the trajectory.

This trajectory requires that the spacecraft maintain a high acceleration for long durations. For interplanetary transfers, days, weeks or months of constant thrusting may be required. As a result, there are no currently available spacecraft propulsion systems capable of using this trajectory. It has been suggested that some forms of nuclear (fission or fusion based) or antimatter powered rockets would be capable of this trajectory.

More practically, this type of maneuver is used in low thrust maneuvers, for example with ion engines, Hall-effect thrusters, and others. These types of engines have very high specific impulse (fuel efficiency) but currently are only available with fairly low absolute thrust.

Rendezvous and docking

Orbit phasing

In astrodynamics orbit phasing is the adjustment of the time-position of spacecraft along its orbit, usually described as adjusting the orbiting spacecraft's true anomaly.

Space rendezvous and docking

Gemini 7 photographed from Gemini 6 in December 1965

A space rendezvous is an orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance (e.g. within visual contact). Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain at a constant distance through orbital station-keeping. Rendezvous may or may not be followed by docking or berthing, procedures which bring the spacecraft into physical contact and create a link between them.

Introduction to entropy

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