FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1973
1973 - 1683.PDF
FLIGHT International, 14 June 1973 Power priority for Skylab H IGH TEMPERATURES and low power had severely restricted effective experiment operation as the Skylab crew, mission commander Charles "Pete" Conrad, Dr Joseph Kerwin and Paul Weitz, completed their first working week aboard the space station. The internal temperature, dropping much more slowly than anticipated, had reached 88°F by the middle of last week, but Nasa officials reaffirmed their belief that it would stabilise at about 80°F, or 10°F above normal. The astronauts moved into the station on May 29 after spending the first three nights back in the Apollo command module while the worst of the temperature eased off. They are now sleeping in relative comfort using restraining sacks fitted up in the three small partitioned "bedrooms" on the lower deck of the workshop. The temperature last week was still too high to allow full use of the pedal exercising machine, a matter stated by Nasa to have been the subject of a private conversation between Conrad and Johnson Space Centre director Christopher Kraft. The private talk aroused some speculation because ground rules stipulate that all communications are made publicly except for extreme operational emergencies, for the astronauts' daily discussion with a doctor on Earth and for their weekly communication with their families. Chief astronaut Donald Slayton reported that the ground personnel had made "an error in judgment" in permitting the private talk. Most of the limitations under which Skylab has operated since launch should by now be minimised, if a special space walk, scheduled last week in a renewed attempt to release the jammed solar panel, has been successful. The spacewalk was formally approved by Nasa on June 4 after extensive water-tank simulation on Earth to devise the best means of achieving the objective. If still serviceable, the remain ing solar panel, which was jammed by a strip of aluminium from the meteoroid shield as it was torn off during launch, should provide an additional 3kW-5kW. Surplus power from the fuel cells of the Apollo service module was likely to have been depleted by June 13, according to Nasa estimates. Unless the panel is opened, therefore, the last eight days of the 28-day mission will be almost: completely inactive as far as the experiments are concerned. The power supply problems were increased early last week when some batteries failed. The station has been operating off only the solar arrays attached to the Apollo Telescope Mount, providing about 4kW-6kW, or half the requirements. This has proved barely sufficient for operation of the ATM itself which has, however, recorded some significant solar activity. When the ATM is operating, the spacecraft circles the Earth in a constant attitude relative to the Sun so that the ATM (and its solar arrays) are constantly fac ing the Sun, except when eclipsed by the Earth. The opera tion of the Earth-resources experiments, however, requires that the spacecraft is turned away from the Sun so that its attitude follows the curvature of the Earth. During these periods, power is drawn from a set of 18 250W batteries in Skylab as seen from below from the Apollo command module during the first examination by the arriving astronauts, shows the remaining solar panel cover partially deployed. Two of the ATM solar panels can be seen projecting at the top left corner the ATM which are recharged by the solar arrays when in sunlight. One of these batteries failed early in the mission, leaving 4-25kW available. Four more failed later during a medical experiment and it was found that these had automatically cut out when only 55 per cent of their charge was exhausted. The batteries are regulated to cut out when they reach 80 per cent depletion. Three of the batteries were brought back into full operation but, with two now out of service, the available power is down by 12 per cent, or limited to 4kW. On the first day of experiment operation, power demand averaged 4-4kW and reached a peak of 4 • 8kW. The loss of batteries has since placed severe limita tions on the use of instruments. Provision of more power has become top priority, hence the approval of the space walk. A special procedure had been worked out for this, making the best use of on-board equipment. The two astronauts were to perform the space walk, one to assist and remain near the hatch. First attempts were to be made by the crewmen working from the hatch with a 25ft pole. Failure of this would have meant that one would have to work his way along the outside of the workshop and first try to lever off the obstructive strip with a crowbar and then to cut it off with a bone saw from Dr Kerwin's medical kit. Nasa is also looking at possibilities of subsequent crews bringing solar arrays up with them either in the form of a furled sheet, to be deployed by the astronauts, or attached to a module which could be docked in the spare port of the multiple docking adapter. Another plan which achieved some importance last week, before being ruled out, involved extending the astronauts' stay on board by ten days. On June 22, the day they are due to leave, the orbit and Earth would have reached such a position that the ATM solar array could have been kept exposed to the Sun during Earth- resources work, effectively supplying an additional 3kW, or more, for a period of ten days. It was decided, however, that the crew should return to Earth on June 22 as scheduled and it has been pro posed that the second crew launch be brought forward. The second crew consists of Alan Bean, Owen Garriott and Jack Lousma. Skylab. programme director William Schneider stated last week that, as the station had been exposed to unexpected usage, he considered it prudent to bring the launch date forward to July 27 from August 8. Astronomical observations had last week centred on study of the Sun using a coronograph, one of a cluster of
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
