Credit: NASA. 34,755 bytes. 320 x 245 pixels.
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| ISS Final Stage - The International Space Station in as planned at completion. From top to bottom,
Soyuz rescue craft, Russian Service Module, Functional Cargo Block,
NASA docking module, US Habitat Module, truss, US Lab Module, European
Columbus and Japanese JEM modules, docked US space shuttle. The inside
panels on the trusses are thermal control system radiators; four sets
of blue solar panels are at the end of each truss. The station will
orbit at an altitude of up to 370 kilometres at an inclination of
51.6 degrees. The solar panels will generate 110 kilowatts of power, with
46 kilowatts available for science experiments. Total station
pressurised volume will be 1300 cubic metres, over three times that of
Mir. Credit: NASA. 34,755 bytes. 320 x 245 pixels. |
In November 1998, on two continents, the first modules of the International Space Station had left the factories and were ready for orbit. Crews were in training for their assigned flights to the station. After fourteen years of tortured development and political upheaval, mankind's outpost in space for the 21st century seems finally ready to go.
President Reagan, in his spend-to-the-death race with the Soviet 'Evil Empire', tasked NASA in 1984 to provide America with space station Freedom. NASA lumbered into action. The current mantra 'faster, better, cheaper' was then unknown. A bizarre programme-management scheme had each station subsystem being developed by different NASA centres and contractors. By 1990, the first operational date had slipped from 1994 to 1997 and the station had ballooned into a $30 billion, 298-tonne monster.
Meanwhile, the Russians successfully assembled and operated the 124-tonne Mir station. The station's modules were evolved from those of the secret military Almaz station of the 1970s. Mir and its crews whirled round and round the world, through the collapse of the Soviet Union and Russian economic meltdown. By 1993, Russia had acquired unmatched experience in long-duration human flight, but it was apparent that there was no money for the follow-on Mir-2.
By this time, NASA had scaled down its station in the seventh redesign in nine years. This more modest station Alpha deleted most of the original science experiments, but would still cost more than Clinton was willing to spend. In October 1993, with the gunfire of the coup attempt outside their windows, NASA negotiators in Moscow agreed to the 'International Space Station' (ISS), a merger of stations Alpha and Mir-2.
The latest crisis came in April 1997 when NASA noticed that the essential Service Module, originally the core for the Mir-2 station, was still only an empty hull even though it was meant to be launched eight months later. Without the Service Module, the station would not have the rocket power needed to reboost its orbit and prevent it from spiralling in to a fiery re-entry. After an American ultimatum, Yeltsin put his government deeper into debt and saved the program.
Construction of the ISS began with the launch of the NASA-funded, Russian-built Zarya Functional Cargo Block (FGB, from its Russian name) in November 1998. A few weeks later, the shuttle *Endeavour* rendezvoused with Zarya and attached the first American module. Astronauts Jerry Ross and Jim Newman conducted three spacewalks to make electrical and data bus connections. By July 1999, it is hoped that the delayed Russian Service Module will dock with the complex.
Thereafter, permanent occupancy can begin. In January 2000, veteran cosmonauts Yuri Gidzenko, Sergei Krikalyov and astronaut Bill Shepherd will arrive aboard a Russian Soyuz spacecraft for a five-month stay. No less than 33 assembly flights are scheduled through to July 2004, with additional equipment, habitation or laboratory modules being added every month. At first the cluster will resemble Mir. But on the fourteenth flight, in the spring of 2001, the long truss will be installed. This will be extended on following missions and huge solar wings deployed, until the station achieves its final form.
NASA plans six research facilities initially devoted to fluids and combustion, materials science, gravitational biology and human zero-gravity adaptation. The first US lab module will be attached in March 2000, with the Canadian remote manipulating system arriving a month later. The Japanese JEM module is planned for July 2002. Europe's Columbus module is scheduled for October 2003.
A major concern is whether the Americans will have the nerve to stay the course when inevitable mishaps occur. The station, like Mir, will require constant maintenance. It could not be shut down if America stopped shuttle flights for years as it did after the *Challenger* explosion. Russian engineers calculate that there is a 23% chance that the exposed Service Module will be punctured by orbital debris during the lifetime of the station. Although the alloy and type of construction there would contain any puncture within a 70x70-centimetre panel, they believe an impact on the American section would result in fractures propagating quickly across a 400x400-centimetre area, leading to explosive decompression, an uncontrollable spin and rapid break-up of the station. Fortunately the probability of such an impact is only 2%.
The reality of 2001 will not quite match the vision of the film of the same name. But if all goes well there will be an international space station, where crews from all the nations of the Earth conduct experiments in the spirit of international science instead of that of nationalist competition. The systems proved on the station will then be available for the outward push of mankind, together, to Mars, Europa and 'Beyond the Infinite'.
Appendix - Comparison of ISS with Freedom and Alpha Stations:
ISS final configuration is similar to Alpha configuration 'A' in comparison to original 'Freedom' configuration:
Freedom A B C Cost to Finish ($Bil) 20 16.5 19.3 15.1 Complete Date 09/2000 10/2000 12/2001 01/2001 Annual Ops Cost ($Bil) 2.4 1.4 1.5 1.0 Crew Size 4 4 4 4 Research Hours/Year 6566 6724 6566 6866 Alpha Gimbal Y N Y N Total Avg. Power (kW) 68.3 57 68.3 46.5-62.9 Avg. User Power (kW) 34.2 31 40.3 24.4-40.2 Total Pressrzd Vol(m^3) 878 760 878 1117 User Science Racks 46 39 46 72 External Attach Sites 14 21 15 14 Tot. Asmbl/Outfit Flights 20 16 20 9 Tot. Asmbl EVA Hours 381 224 311 24 Logistics Flights/Year 4 6 6 6 Maintain EVA Hours/Year 253 187 253 80Major Events: .
The ARD was an 80 percent scale model of the Apollo Command Module, and a technology test for a possible International Space Station Crew Rescue Vehicle. Equipment included a TDRS satellite communications system; a GPS navigation system; 7 DASA 40 kgf hydrazine attitude control thrusters; a 2.8 m diameter heat shield; three 23 metre diameter parachutes, and a SARSAT recovery beacon. The ARD separated from the Ariane EPS upper stage at 12 minutes 2 seconds after launch. ARD and the EPC stage manoeuvred into a 1 km x 830 km orbit, guaranteeing re-entry at the end of the first orbit. The spacecraft splashed down in the Pacific at 3.69 degrees N, 153.35 degrees W, and was successfully recovered by the French Navy.
First attempted launch of STS-88 was scrubbed at 09:03 GMT on December 3 due to a problem with a hydraulic system sensor. Launch came the next day, with Endeavour entering an initial 75 km x 313 km x 51.6 degree orbit. Half an orbit after launch, at 09:19 GMT, Endeavour fired its OMS engines to raise the orbit to 180 km x 322 km x 51.6 degree.
On December 5 at 22:25 GMT Nancy Currie unberthed the Unity space station node from the payload bay using the RMS arm. She then moved the Unity to a position docked to the Orbiter Docking System in the payload bay in readiness for assembly with the Russian-launched Zarya FGB ISS component. After rendezvous with the Zarya FGB module, on December 6 at 23:47 GMT Endeavour grappled Zarya with the robot arm, and at 02:07 GMT on December 7 it was soft docked to the PMA-1 port on Unity. After some problems hard dock was achieved at 02:48 GMT. Unity and Zarya then formed the core of the future International Space Station. Ross and Newman made three space walks to connect cables between Zarya and Unity, on December 7, 9 and 12. On the last EVA a canvas tool bag was attached to the exterior of Unity to provide tools for future station assembly workers. Docking cables were disconnected to prevent Unity and Zarya from inadvertently undocking. Following an internal examination of the embryonic space station, Endeavour undocked at 20:30 GMT on December 13. The SAC-A and Mightysat satellites were ejected from the payload bay on December 14 and 15. Deorbit burn was December 16 at 03:48 GMT, and Endeavour landed at 04:53:29 GMT, on Runway 15 at the Kennedy Space Center.
Payloads included:
This was the first launch in the assembly of the International Space Station. The Zarya FGB was funded by NASA and built by Khrunichev in Moscow under subcontract from Boeing for NASA. Its design from the TKS military station resupply spacecraft of the 1970’s and the later 77KS Mir modules. Zarya included a multiple docking adapter, a pressurised cabin section, and a propulsion/instrument section with a rear docking port. Initial orbit was 176 lm x 343 km x 51.6 degrees. By November 25 it had manoeuvred to a 383 km x 396 km x 51.7 degree orbit, awaiting the launch of Shuttle mission STS-88 which docked the Unity node to it.
Began assembly of International Space Station. Connected cables between Zarya and Unity modules.
Continued assembly of International Space Station. Connected cables between Zarya and Unity modules and deployed antennae.
Completed initial assembly of International Space Station. A canvas tool bag was attached to the exterior of Unity to provide tools for future assembly workers. Also disconnected some docking cables, so that Unity and Zarya could no longer undock.
X-38 atmospheric test vehicle V-132 was dropped from carrier plane NB-52 # 8 at 16:17 GMT. The V-132 subscale version of the X-38 successfully deployed its parafoil and glided to a landing on the lakebed after a 9 minute flight. V-132 tested the rudders and flaps; the simpler V-131, which made two drop tests earlier, tested the parafoil control system.
At 0:721 GMT on June 5 the Starshine satellite was ejected into a 379 x 396 km x 51.6 degree orbit from a canister at the rear of STS-96 Space Shuttle Discovery's payload bay. The small Starshine satellite, built by NRL, was to be observed by students as part of an educational exercise.
Discovery docked at the PMA-2 end of the International Space Station PMA-2/Unity/PMA-1/Zarya stack. The crew transferred equipment from the Spacehab Logistics Double Module in the payload bay to the interior of the station. Tammy Jernigan and Dan Barry made a space walk to transfer equipment from the payload bay to the exterior of the station. The ODS/EAL docking/airlock truss carried two TSA (Tool Stowage Assembly) packets with space walk tools. The Integrated Cargo Carrier (ICC), built by Energia and DASA-Bremen, carried parts of the Strela crane and the US OTD crane as well as the SHOSS box which contains three bags of tools and equipment to be stored on ISS's exterior.
The STS-96 payload bay manifest:
On May 30 at 02:56 GMT Tammy Jernigan and Dan Barry entered the payload bay of Discovery from the tunnel adapter hatch, and made a 7 hr 55 min space walk, transferring equipment to the exterior of the station.
On May 31 at 01:15 GMT the hatch to Unity was opened and the crew began several days of cargo transfers to the station. Battery units and communications equipment were replaced and sound insulation was added to Zarya. Discovery undocked from ISS at 22:39 GMT on June 3 into a 385 x 399 km x 51.6 degree orbit, leaving the station without a crew aboard. On June 5 the Starshine satellite was ejected from the payload bay. The payload bay doors were closed at around 02:15 GMT on June 6 and the deorbit burn was at 04:54 GMT. Discovery landed on runway 15 at Kennedy Space Center at 06:02 GMT.
On May 30 at 02:56 GMT Tammy Jernigan and Dan Barry entered the payload bay of space shuttle Discovery from the tunnel adapter hatch. During the space walk they transferred equipment to the exterior of the station.
Objective of mission STS-101 was repair, resupply and construction tasks aboard the international space station. This was the first launch with new electronic cockpit displays and other upgrades. The solid boosters separated at 10:13 GMT and the main engines cutoff at 10:19 GMT. The external tank, ET-102 then separated, with both orbiter and ET-102 in a 52 x 320 km initial orbit. At 10:54 GMT the OMS engines fired to raise perigee to 159 x 329 km x at 51.6 deg. Atlantis docked with the International Space Station's PMA-2 docking adapter on the Unity node at 04:31 GMT on May 21. At that time the ISS was in a 332 x 341 km orbit.
On May 22 mission specialists Jeff Williams and James carried out external maintenance work on the ISS.
On May 23 at 00:03 GMT the Atlantis crew opened the first hatch to PMA-2 and entered the Station. The crew replaced a set of batteries in Zarya, installed fans and ducting to improve airflow, and delivered supplies and equipment. Three hour-long orbit raising burns on May 24 and 25 by the RCS engines on Atlantis raised the station to a 372 x 380 km x 51.6 deg orbit.
The STS-101 crew left the station on May 26, closing the PMA-2 hatch at 08:08 GMT and undocking at 23:03 GMT. Atlantis performed a 180 degree flyaround of the station and departed the vicinity around 23:44 GMT.
Atlantis closed its payload bay doors around 02:30 GMT on May 29 and fired the OMS engines for deorbit at 05:12 GMT. The vehicle landed on RW15 at Kennedy Space Center at 06:20 GMT. Atlantis was to be turned around for the next ISS shuttle flight, STS-106.
Left in orbit was the renovated International Space Station, equipped with an upgraded electrical system, new fans, filters, fire extinguishers, smoke detectors and communications gear.
The crew reattached the US crane, attached the Russian Strela transfer boom, and replaced a faulty antenna on the Unity node. EVA handrails were fixed to the station exterior for use on later spacewalks.
Progress M1-3 automatically docked with the International Space Station on August 8 at 20:13 GMT at the rear Zvezda port. The supply ship began refuelling of the station a few days later. It remained attached for offloading of its dry cargo by the STS-106 crew. It later separated and was deorbited over the Pacific on 1 November.
Atlantis was launched from Kennedy Space Center's Launch Complex 39B. Solid rocket boosters RSRM-75 and external tank ET-103 were used to loft the orbiter into space. The inital orbit of 72 x 328 km x 51.6 deg was circularised by the Shuttle's OMS engines at apogee.
Atlantis docked with the PMA-2 adapter on the International Space Station at 05:51 GMT on September 10. The orbiter's small RCS engines were used to gently reboost the station's orbit several times.
Astronauts Lu and Malenchenko made a spacewalk on September 11 beginning at 04:47 GMT. They rode the RMS arm up to Zvezda and began installing cables, reaching a distance of 30 meters from the airlock when installing Zvezda's magnetometer. Total EVA duration was 6 hours 21 minutes.
During their 12-day flight, the astronauts spent a week docked to the International Space Station during which they worked as movers, cleaners, plumbers, electricians and cable installers. In all, they spent 7 days, 21 hours and 54 minutes docked to the International Space Station, outfitting the new Zvezda module for the arrival of the Expedition One crew later this fall.
The Shuttle undocked from ISS at 03:44 GMT on September 18 and made two circuits of the station each lasting half an orbit, before separating finally at 05:34 GMT. The payload bay doors were closed at 04:14 GMT on September 20 and at 06:50 GMT the OMS engines ignited for a three minute burn lowering the orbit from 374 x 386 km x 51.6 deg to 22 x 380 km x 51.6 deg. After entry interface at 07:25 GMT, the orbiter glided to a landing on runway 15 at Kennedy Space Center with main gear touchdown at 07:56:48 GMT for a mission duration of 283 hr 11min.
Astronauts Lu and Malenchenko made a spacewalk on September 11 beginning at 04:47 GMT. They rode the RMS arm up to Zvezda and began installing cables, reaching a distance of 30 meters from the airlock when installing Zvezda's magnetometer.
STS-92 was a space station assembly flight to bring the Z-1 Truss (mounted on a Spacelab pallet), Control Moment Gyros, Pressurised Mating Adapter-3 (PMA-3) and two DDCU (Heat pipes) to the International Space Station.
The RSRM-76 solid rocket boosters separated at 23:19 GMT and main engine cut-off (MECO) came at 23:25 GMT. External tank ET-104 separated into a 74 x 323 km x 51.6 deg orbit. At apogee at 00:01 GMT on Oct 12, Discovery's OMS engines fired to raise perigee to a 158 x 322 km x 51.6 deg orbit; ET-104 re-entered over the Pacific around 00:30 GMT. At Oct 12 on 03:01 GMT the NC1 burn raised the orbit to 180 x 349 km; NC3 on Oct 12 to 311 x 375 km; and the TI burn at 14:09 GMT on Oct 13 to 375 x 381 km x 51.6 deg. Discovery's rendezvous with the International Space Station came at 15:39 GMT on Oct 13, with docking at 17:45 GMT. The spaceship docked with PMA-2, the docking port on the +Y port of the Space Station's Unity module. Hatch was open to PMA-2 at 20:30 GMT the same day.
STS-92 Cargo Manifest
Total payload bay cargo: ca. 14,800 kg
The Z1 first segment of the space station truss was built by Boeing/Canoga Park and was 3.5 x 4.5 meters in size. It was attached to the +Z port on Unity. Z1 carried the control moment gyros, the S-band antenna, and the Ku-band antenna.
PMA-3, built by Boeing/Huntington Beach, was docked to the -Z port opposite Z1. PMA-3 was installed on a Spacelab pallet for launch.
On October 14 at 16:15 GMT the Z1 segment was unberthed from the payload bay and at around 18:20 GMT it was docked to the zenith port on the Unity module.
On October 15 at 14:20 GMT the ODS airlock was depressurised, beginning a spacewalk by Bill McArthur and Leroy Chiao. Official NASA EVA duration (battery power to repress) was 6 hours 28 minutes.
The second spacewalk was on October 16, with Jeff Wisoff and Mike Lopez-Alegria. The suits went to battery power at 14:15 GMT and Wisoff left the airlock at 14:21 GMT. Repressurisation began at 21:22 GMT for a duration of 7 hours 07minutes.
Leroy Chiao and Bill McArthur began the third STS-92 EVA at 15:30 GMT on October 17, completing their work at 22:18 GMT for a total time of 6 hours 48 minutes.
After the spacewalk, Discovery completed the second of the three station reboosts scheduled for STS-92. They fired reaction control system jets in a series of pulses of 1.4 seconds each, over a 30-minute period, gently raising the station's orbit by about 3.1 km.
The last of four successful spacewalks began on 18 October at 16:00 GMT and ended at 22:56 GMT, lasting 6 hours and 56 minutes. Jeff Wisoff and Mike Lopez-Alegria each jetted slowly through space above Discovery's cargo bay.
After the space walk, Discovery completed the third and final reboost of the space station.
On 19 October the astronauts worked within the ISS. They completed connections for the newly installed Z1 external framework structure and transferred equipment and supplies for the Expedition One first resident crew of the Station. The crew also tested the four 290-kg gyroscopes in the truss, called Control Moment Gyros, which will be used to orient the ISS as it orbits the Earth. They will ultimately assume attitude control of the ISS following the arrival of the U.S. Laboratory Destiny. The tests and the transfer of supplies into the Russian Zarya Module took longer than expected. As a result, the crew's final departure from the Station's Unity module was delayed. Melroy and Wisoff took samples from surfaces in Zarya to study the module's environment. They then unclogged the solid waste disposal system in the Shuttle's toilet, which was restored to full operation after a brief interruption in service.
Discovery undocked from the ISS at 16:08 GMT on 20 October. The final separation burn was executed about 45 minutes after undocking. The crew had added 9 tonnes to the station's mass, bringing it to about 72 tonnes. The return to earth, planned for 22 October, was delayed repeatedly due to high winds at the Kennedy landing site. The landing was finally made at Edwards Air Force Base, California, on October 24, at 22:00 GMT.
The astronauts connected cables between Z1 and Unity, relocated the SASA S-band antenna on Z1, and deployed Z1's SGANT Ku-band antenna. They then took the port ETSD (EVA stowage) box from the Spacelab pallet and installed it on Z1.
Wakata aboard the shuttle used the RMS arm to unberth the PMA-3 docking unit from the SLP pallet at 16:14 GMT, and docked it to Unity at 17:40 GMT. Wisoff and Lopez-Alegria first unbolted PMA-3 from the SLP and then guided Wakata through the delicate alignment process as PMA-3 was removed from the bay and attached to the Station.
The astronauts installed two 58 kg DDCU DC-to-DC converter units atop the International Space Station's Z1 Truss. The DDCUs, will convert electricity generated by the solar arrays to be attached during the next shuttle mission. The spacewalkers also completed power cable connections on both the Z1 truss and newly installed docking port, PMA-3. They connected and reconfigured cables to route power from Pressurised Mating Adapter-2 to PMA-3 for the arrival of Endeavour and the STS-97 crew next month. They also attached a second tool storage box on the Z1 truss, providing a place to hold the tools and spacewalking aids for future assembly flights. McArthur stocked the boxes with tools and hardware that had been attached to the Unity module. STS-96 Astronauts Tammy Jernigan and Dan Barry had left the tools on the outside of Unity during a May 1999 spacewalk.
Jeff Wisoff and Mike Lopez-Alegria each jetted slowly through space above Discovery's cargo bay, demonstrating the small rescue nitrogen powered SAFER backpack (Simplified Aid for EVA Rescue). This would be used in the future to help a drifting astronaut regain the safety of the spacecraft. Each astronaut performed one 15 meter flight with the SAFER while attached to the shuttle with a long tether. Lopez-Alegria and Wisoff, with Koichi Wakata operating the arm, also completed a series of wrap-up tasks during the EVA. They removed a grapple fixture from the Z1 truss, opened and closed a latch assembly that will hold the solar array truss when it arrives, deployed a tray that will be used to provide power to the U.S. Laboratory Destiny, and tested the manual berthing mechanism latches that will support Destiny. Wisoff opened and closed the latches on the capture assembly for the P6 solar arrays using a pistol grip tool. With it he made more than 125 turns to open the latches, then closed and reopened them. He left the capture latch, called 'the claw,' ready to receive the solar arrays, to be installed by the STS-97 crew. An exercise to test techniques for returning an incapacitated astronaut to the air lock was cancelled because of time constraints.