19 April 1770

Captain James Cook sights the eastern coast of what is now Australia.

On April 19, 1770, Captain James Cook spotted and claimed the East Coast of Australia

Cook was born in north-east England in 1728, and in his late teens, he worked on ships along the English coast and the Baltic Sea.

In 1755, he joined the navy, seeing action in Canada and surveying the St Lawrence River, which resulted in the British capture of Quebec.

On 26 August 1768, The HMB Endeavour set sail from England’s Plymouth Harbour, under the command of Captain Cook, an accomplished surveyor, astronomer and navigator.

The ship’s crew was instructed to make for Tahiti, where they would observe and record the transit of Venus across the face of the Sun.

Cook also carried additional instructions from the Admiralty ordering him to explore the Southern Ocean in search of Terra Australis incognita – the unknown southern land.

After the war, Cook’s skills were put on further display when he mapped the coast of the Canadian island of Newfoundland.

Under commission from the Royal Society, the Endeavour entered the South Pacific via Cape Horn, reaching Tahiti in April 1769 where the crew observed the transit of Venus on 3 June.

19 April 1971

The first space station, Salyut 1 is launched.

Salyut 1 was the first space station of any kind, launched into low Earth orbit by the Soviet Union on April 19, 1971. The Salyut program followed this with five more successful launches out of seven more stations. The final module of the program, Zvezda became the core of the Russian segment of the International Space Station and remains in orbit.

Background
Salyut 1 originated as a modification of the military Almaz space station program then in development. After the landing of Apollo 11 on the Moon in July 1969, the Soviets began shifting the primary emphasis of their manned space program to orbiting space stations, with a possible lunar landing later in the 1970s if the N-1 booster became flight-worthy. One other motivation for the space station program was a desire to one-up the US Skylab program then in development. The basic structure of Salyut 1 was adapted from the Almaz with a few modifications and would form the basis of all Soviet space stations through Mir.

Civilian Soviet space stations were internally referred to as “DOS”, although publicly, the Salyut name was used for the first six DOS stations. Several military experiments were nonetheless carried on Salyut 1, including the OD-4 optical visual ranger, the Orion ultraviolet instrument for characterizing rocket exhaust plumes, and the highly classified Svinets radiometer.

Construction and operational history
Construction of Salyut 1 began in early 1970, and after nearly a year it was shipped to the Baikonur Cosmodrome. Some remaining assembly work had yet to be done and this was completed at the launch center. The Salyut programme was managed by Kerim Kerimov, chairman of the state commission for Soyuz missions.

Launch was planned for April 12, 1971 to coincide with the 10th anniversary of Yuri Gagarin’s flight on Vostok 1, but technical problems delayed it until the 19th. The first crew launched later in the Soyuz 10 mission, but they ran into troubles while docking and were unable to enter the station; the Soyuz 10 mission was aborted and the crew returned safely to Earth. A replacement crew launched in Soyuz 11 and remained on board for 23 days. This was the first time in the history of spaceflight that a space station had been manned, and a new record time was set in space. This success was, however, short-lived when the crew was killed during re-entry, as a pressure-equalization valve in the Soyuz 11 re-entry capsule had opened prematurely, causing the crew to asphyxiate. After this accident, all missions were suspended while the Soyuz spacecraft was redesigned. The station was intentionally destroyed by de-orbiting after six months in orbit, because it ran out of fuel before a redesigned Soyuz spacecraft could be launched to it.

Structure
At launch, the announced purpose of Salyut was to test the elements of the systems of a space station and to conduct scientific research and experiments. The craft was described as being 20 m in length, 4 m in maximum diameter, and 99 m3 in interior space with an on-orbit dry mass of 18,425 kg. Of its several compartments, three were pressurized, and two could be entered by the crew.

Transfer compartment
The transfer compartment was equipped with the only docking port of Salyut 1, which allowed one Soyuz 7K-OKS spacecraft to dock. It was the first use of the Soviet “probe and drogue” type docking system that allowed internal crew transfer, a system that is in use today. The docking cone had a 2 m front diameter and a 3 m aft diameter.

Main compartment
The second, and main, compartment was about 4 m in diameter. Televised views showed enough space for eight big chairs, several control panels, and 20 portholes.

Auxiliary compartments
The third pressurized compartment contained the control and communications equipment, the power supply, the life support system, and other auxiliary equipment. The fourth, and final, unpressurized compartment was about 2 m in diameter and contained the engine installations and associated control equipment. Salyut had buffer chemical batteries, reserve supplies of oxygen and water, and regeneration systems. Externally mounted were two double sets of solar cell panels that extended like wings from the smaller compartments at each end, the heat regulation system’s radiators, and orientation and control devices.

Salyut 1 was modified from one of the Almaz airframes. The unpressurized service module was the modified service module of a Soyuz craft.

Orion 1 Space Observatory
The astrophysical Orion 1 Space Observatory designed by Grigor Gurzadyan of Byurakan Observatory in Armenia, was installed in Salyut 1. Ultraviolet spectrograms of stars were obtained with the help of a mirror telescope of the Mersenne system and a spectrograph of the Wadsworth system using film sensitive to the far ultraviolet. The dispersion of the spectrograph was 32 Å/mm, while the resolution of the spectrograms derived was about 5 Å at 2600 Å. Slitless spectrograms were obtained of the stars Vega and Beta Centauri between 2000 and 3800 Å. The telescope was operated by crew member Viktor Patsayev, who became the first man to operate a telescope outside the Earth’s atmosphere.

19 April 2013

The suspect in the Boston Marathon bombing, Tamerlan Tsarnaev, is killed in a shootout with police.

An investigation involving more than 1,000 federal, state and local law enforcement personnel quickly was launched. A breakthrough in the case came less than two days later, when FBI analysts, who had pored through thousands of videos and photographs taken from security cameras in the area where the attack occurred, pinpointed two male suspects. The FBI released surveillance-camera images of the men, whose identities were then unknown, on the evening of April 18.

That night at around 10:30, Sean Collier, a 27-year-old police officer at the Massachusetts Institute of Technology, was shot dead in his patrol car on the school’s Cambridge campus. Authorities later would link the murder to the Tsarnaev brothers, who allegedly attempted to steal the officer’s service weapon. Soon after Collier was killed, Tamerlan Tsarnaev allegedly carjacked a Mercedes SUV at gunpoint, taking the driver hostage and telling him he was one of the Boston Marathon bombers. Dzhokhar Tsarnaev followed behind in a Honda Civic before joining his older brother and the hostage in the SUV. The brothers drove around the Boston area with their hostage, forcing him to withdraw money from an ATM and discussing driving to New York City.

When they stopped at a Cambridge gas station, the hostage escaped and called police, informing them the SUV could be tracked by his cellphone, which was still in the vehicle. Shortly after midnight, police in the Boston suburb of Watertown spotted the suspects in the stolen SUV and Honda Civic and tried to apprehend them. A gun battle broke out on a Watertown street, with the Tsarnaevs exchanging fire with the police and hurling explosive devices at them. One officer was seriously injured by gunshots but survived. After Tamerlan Tsarnaev was tackled by police, Dzhokhar Tsarnaev drove the stolen SUV straight at them, running over his brother before speeding away. He abandoned the SUV nearby then fled on foot. A gravely wounded Tamerlan Tsarnaev, whose body was riddled with bullets, was taken to a hospital, where doctors were unable to resuscitate him.