Daily Archives: May 13, 2017

"Space Station Alpha" redirects here. For the Bigelow Aerospace project, see Space Complex Alpha.

Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after several cutbacks, the project evolved into the International Space Station program.

In the early 1980s, with the Space Shuttle completed, NASA proposed the creation of a large, permanently manned space station, which then-NASA-Administrator James M. Beggs called "the next logical step" in space. In some ways it was meant to be the U.S. answer to the Soviet Mir. NASA plans called for the station, which was later dubbed Space Station Freedom, to function as an orbiting repair shop for satellites, an assembly point for spacecraft, an observation post for astronomers, a microgravity laboratory for scientists, and a microgravity factory for companies.

Reagan announced plans to build Space Station Freedom in 1984, stating: "We can follow our dreams to distant stars, living and working in space for peaceful economic and scientific gain."

The 1990 Space Exploration Initiative called for the construction of the Space Station Freedom. Following the presidential announcement, NASA began a set of studies to determine the potential uses for the space station, both in research and in industry, in the U.S. or overseas. This led to the creation of a database of thousands of possible missions and payloads; studies were also carried out with a view to supporting potential planetary missions, as well as those in low-earth orbit.

Several Space Shuttle missions in the 1980s and early 1990s included spacewalks to demonstrate and test space station construction techniques. After the establishment of the initial baseline design, the project evolved extensively, growing in scope and cost.

In April 1984, the newly established Space Station Program Office at Johnson Space Center produced a first reference configuration; this design would serve as a baseline for further planning. The chosen design was the "Power Tower", a long central keel with most mass located at either end. This arrangement would provide enough gravity gradient stability to keep the station aligned with the keel pointed towards the Earth, reducing the need for thruster firings. Most designs featured a cluster of modules at the lower end and a set of articulated solar arrays at the upper end. It also contained a servicing bay. In April 1985, the program selected a set of contractors to carry out definition studies and preliminary design; various trade-offs were made in this process, balancing higher development costs against reduced long-term operating costs.

In March 1986, the System Requirements Review modified the configuration to the "Dual-Keel" design, which moved the modules to the central trussplacing them at the center of gravity, providing a better microgravity environment. However, the desire to maintain tidal alignment led to the use of increased truss structure, with two large "keels".

As the international involvement became more organized, the number of U.S. lab modules was reduced from two to one, taking into consideration the provision of space in the European and Japanese modules. Following this, the design was extensively "scrubbed" to remove inefficiencies; this led to a large number of subsystems being revised or removed, the deferral of plans for an Orbital Maneuvering Vehicle to be based at the station, and the use of only a single habitation module for a crew of eight.

In May 1986, NASA produced a report which had studied the assembly sequence with the intent of providing early "man-tended" capacity, ensuring that at an early stage, despite the station not being able to support a crew, research work could be carried out by occasional visiting Shuttle flights. Following the Challenger accident, a Critical Evaluation Task Force was set up to reassess the validity and safety of the Station design. While this validated the use of the Dual-Keel design, post-Challenger safety concerns led to changes in the assembly plans, as well as assorted minor changes. Johnson Space Center had previously expressed misgivings about the amount of EVA work needed to assemble the station, which were addressed, as were the Shuttle payload reductions stemming from safety improvements post Challenger.

In September 1986, a major cost review of the program was undertaken from the post-Challenger baseline; this review was intended to ensure that NASA had a solid basis for its commitment to cost and schedule. The review found that the total development cost for the Dual-Keel configuration would cost US$18.2 billion (in FY1989 dollars), and a slip in the first-element launch (FEL) date from January 1993 to January 1994.

At the same time, late 1986, NASA carried out a study into new configuration options to reduce development costs; options studied ranged from the use of a Skylab-type station to a phased development of the Dual-Keel configuration. This approach involved splitting assembly into two phases; Phase 1 would provide the central modules, and the transverse boom, but with no keels. The solar arrays would be augmented to ensure 75kW of power would be provided, and the polar platform and servicing facility were again deferred. The study concluded that the project was viable, reducing development costs while minimizing negative impacts, and it was designated the Revised Baseline Configuration. This would have a development cost of US$15.3 billion (in FY1989 dollars) and FEL in the first quarter of 1994. This replanning was endorsed by the National Research Council in September 1987, which also recommended that the long-term national goals should be studied before committing to any particular Phase 2 design.

During 1986 and 1987, various other studies were carried out on the future of the U.S. space program; the results of these often impacted the Space Station, and their recommendations were folded into the revised baseline as necessary. One of the results of these was to baseline the Station program as requiring five shuttle flights a year for operations and logistics, rotating four crew at a time with the aim of extending individual stay times to 180 days.

NASA signed final ten-year contracts for developing the Space Station in September 1988, and the project was finally moving into the hardware fabrication phase.

The Space Station Freedom design was slightly modified in late 1989 after the program's Fiscal 1990 budget again was reducedfrom $2.05 billion to $1.75 billionwhen the design was found to be 23% overweight and over budget, too complicated to assemble, and providing little power for its users. Congress consequently demanded yet another redesign in October 1990, and requested further cost reductions after the fiscal 1991 budget was cut from $2.5 billion to $1.9 billion. NASA unveiled its new space station design in March 1991.

Repeated budget cuts had forced a postponement of the first launch by a year, to March 1995. The Station would be permanently manned from June 1997 onwards, and completed in February 1998. Cost escalation of the project and financial difficulties in Russia led to a briefing between NASA and NPO Energia on Mir-2. In November 1993, Freedom, Mir-2, and the European and Japanese modules were incorporated into a single International Space Station.

Underestimates by NASA of the station program's cost and unwillingness by the U.S. Congress to appropriate funding for the space station resulted in delays of Freedom's design and construction; it was regularly redesigned and re-scoped. Between 1984 and 1993 it went through seven major re-designs, losing capacity and capabilities each time. Rather than being completed in a decade, as Reagan had predicted, Freedom was never built, and no Shuttle launches were made as part of the program.

By 1993, Freedom was politically unviable; the administration had changed, and Congress was tiring of paying yet more money into the station program. In addition, there were open questions over the need for the station. Redesigns had cut most of the science capacity by this point, and the Space Race had ended in 1975 with the Apollo-Soyuz Test Project. NASA presented several options to President Clinton, but even the most limited of these was still seen as too expensive. In June 1993, an amendment to remove space station funding from NASA's appropriations bill failed by one vote in the House of Representatives.[1] That October, a meeting between NASA and the Russian Space Agency agreed to the merger of the projects into what would become the International Space Station. The merger of the project faced opposition by representatives such as Tim Roemer who feared Russia would break the Missile Technology Control Regime agreement and felt the program was far too costly.[2] Proposed bills did not pass Congress.

In 1993, the Clinton administration announced the transformation of Space Station Freedom into the International Space Station (ISS). NASA Administrator Daniel Goldin supervised the addition of Russia to the project. To accommodate reduced budgets, the station design was scaled back from 508 to 353 square feet (47 to 33 m), the crew capacity of the NASA-provided part was reduced from 7 to 3 (while the complete station is manned by 6 but may be increased to 7[3]), and the station's functions were reduced.[4]

Read more here:
Space Station Freedom - Wikipedia

Astronaut Jack Fischer on Fridays spacewalk. Credit: NASA TV/Spaceflight Now

Astronauts Peggy Whitson and Jack Fischer put on spacesuits Friday and headed outside the International Space Station for several repair and maintenance tasks, but the duo only completed part of their originally planned work after a leaky cooling umbilical delayed the start of their spacewalk.

Mission control in Houston marked the official start of the spacewalk at 9:08 a.m. EDT (1308 GMT), when the atmospheric pressure inside the stations Quest airlock passed below 1 pound per square inch.

NASA adjusted the normal starting point for a spacewalk when the astronauts switch their suits to battery power after a troublesome servicing and cooling umbilical forced forced the duo to use their spacesuits internal electrical supply during final spacewalk preps and depressurization of the airlock.

The umbilical was not part of the spacesuit, NASA said, but a piece of support equipment inside the space station. It provides power, cooling and communications capability to the spacesuit before the astronauts exit the space station, according to Rob Navias, the NASA TV commentator for Fridays excursion.

Teams noticed a small water leak in the umbilical early Friday.

Fridays spacewalk was the ninth of Whitsons career, and the first for Fischer, who gleefully remarked on the occasion.

Oh my gosh, this is beautiful, Fischer said as the station sailed 250 miles over the Atlantic Ocean east of Puerto Rico.

Isnt it? Whitson replied.

The biggest slice of awesome pie Ive ever seen, Fischer said.

No awesome sauce? Whitson said, referring to one of Fischers favorite sayings.

How about a ginormous fondu pot bubbling over with piping hot awesome sauce? Fischer joked.

Mission control radioed the astronauts that Fridays spacewalk would be limited to run around four hours, not the six-and-a-half hour duration originally planned, due to the problem.

NASA expected the shortened spacewalk meant Whitson and Fischer would probably only have time to complete one of the jobs planned Friday the replacement of a large avionics box that routes telemetry and power to experiments and spare parts mounted on a depot outside the space station.

In the end, the pair accomplished most of the spacewalks planned objectives.

Their first job was to remove and replace an ExPRESS Carrier Avionics box located on the starboard-side S3 truss of the space station. A replacement unit was delivered to the outpost aboard an Orbital ATK Cygnus supply ship last month.

Whitson and Fischer made quick work of the avionics box swapout, and mission control gave the astronauts the green light to secure a piece of separated insulation on the space stations Japanese robotic arm and work on a data connector for the Alpha Magnetic Spectrometer, a particle detector and cosmic physics experiment outside the station.

Fischer repaired the Japanese robotic arms thermal insulation, while Whitson installed a terminator cap on the AMS instrument, a massive experiment attached to the station truss designed to study dark matter and antimatter.

The terminator cap will enable a telemetry path from AMS, allowing engineers to investigate the performance of cooling pumps inside the instrument that may need to be repaired or replaced on a future spacewalk.

Fischer also got the go-ahead to fasten micrometeoroid and orbital debris shielding to Pressurized Mating Adapter No. 3, which was recently relocated from the Tranquility module to the Harmony module, where it will receive a new docking mechanism next year for future link-ups with commercial crew spaceships developed by Boeing and SpaceX.

The astronauts did not have time to complete other jobs in Fridays spacewalk plan.

The pair planned to set up a new high-definition video camera and a pair of wireless antennas outside the research complex, but those tasks will be deferred to another spacewalk.

Whitson and Fischer returned to the station airlock and began pressurizing it at 1:21 p.m. EDT (1721 GMT), wrapping up a 4-hour, 13-minute spacewalk.

Fridays excursion was the 200th spacewalk in support of space station assembly and maintenance since December 1998, and the fifth this year.

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Follow Stephen Clark on Twitter: @StephenClark1.

Link:
[ May 12, 2017 ] Astronauts complete shortened spacewalk outside International Space Station Mission Reports - Spaceflight Now

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