The automatic abort was initiated by the onboard General Purpose Computers (GPC) when the discharge temperature on MPS Main Engine #3 High Pressure Oxidizer Turbopump (HPOT) exceeded its redline value.

Endeavour did an OMS deorbit burn at 12:09 pm EDT about 4,600 miles (7,400 km) from the landing strip at Edwards Air Force Base.

Throughout the checkout, data takes were recorded over a number of sites, including Raco, Michigan; Bermuda; Bebedouro, Brazil; the Northeast Pacific Ocean and the Juan de Fuca Strait, between the United States and Canada.

The crew successfully engineered an in-flight maintenance procedure to get additional cooling air to the CPCG apparatus after higher than desired temperatures were noted by crystal growth sensors.

Radar data gathering today included much of the East Coast of the United States, current patterns in the Atlantic and Pacific Oceans as well as other bodies of water, desert areas in Africa, and mountainous regions around the world.

The observations were part of a continuing effort to watch the Earth below for evidence of environmental changes that have occurred since the last SRL mission in April.

Radar data was recorded today over much of the East Coast of the United States, the Atlantic and Pacific Oceans, Manitoba, Canada, and French Guiana.

Special readings were taken with the Measurement of Air Pollution by Satellite instrument as intentionally set fires were monitored by scientists from the University of Iowa and the Canadian Forest Service.

The wind field and thermal evolution of the fires will be analyzed to provide a better interpretation of carbon monoxide emissions from the burning forest and to help calibrate color infrared photography taken by the STS-68 crew.

Astronauts relayed information about storms, lightning, fires and clear cutting to the SRL science team that will be used to help understand the radar images and MAPS data on carbon monoxide levels in the atmosphere.

The trim burns adjust the orbit to within 10 metres (33 ft) of where it was in April which will allow scientists to make near identical measurements with the radar equipment to develop a three-dimensional comparison of environmental changes during the six months separating the two missions—STS-59 and STS-68.

Endeavour passed over the Sarobetsu, Japan, calibration site about 3:30 pm CDT, and the Synthetic Aperture Radar sent down real-time data of the area below, allowing scientists to look for changes in the coastline of the islands that may have been due to the large tsunami waves associated with the quake.

STS-68 crew members continued to perform slight maneuvers to fine-tune Endeavour's orbit to intersect its track on the SRL-1 mission to support a new experiment called interferometry.

Radar images over the Sahara desert and the North Atlantic will help scientists evaluate global changes and how they affect the climates in other areas of the world.

Also on October 4, Payload Commander Tom Jones discussed the significance of radar systems and the Earth's environment in an interview with ABC's Good Morning America.

On Wednesday, October 5, 1994, at 4 pm CDT, STS-68 MCC Status Report # 10 reports: Mission to Planet Earth observations by Endeavour's payload bay radar instruments were being suspended temporarily Wednesday afternoon to save fuel while flight controllers work to fix a minor problem involving the shuttle's small reaction control system jets.

The flight control team late Wednesday decided to allow the Shuttle's pointing to vary over a wider range to save thruster fuel while the initial problem was being addressed.

The radar instruments earlier Wednesday collected images over the Kliuchevskoi volcano in Kamchatka, Russia, which erupted about 8 hours after Endeavour's launch Friday.

The technique is expected to yield topographic information of unprecedented clarity by using slightly different shuttle positions to provide three-dimensional images of the terrain below.

Tom Jones, the payload commander for this second flight of SRL, spent some time this morning explaining the importance of the radar's volcanic studies.

Demonstrating with three common types of volcanic rock, Jones explained how the radar's various frequencies allow it to map lava and ash flows around volcanoes.

The work one day may lead to a permanent radar platform in orbit for use in assisting predictions of impending volcanic eruptions and safeguarding people living near active volcanoes.

Late Thursday, Endeavour's astronauts sent down spectacular views of the west coast of California recorded as the shuttle passed about 115 nautical miles (213 km) overhead on its 103rd orbit.

The technique is expected to yield topographic information of unprecedented clarity by using slightly different shuttle positions to provide three-dimensional images of the terrain below.

The Measurement of Air Pollution from Satellite experiment also continues to function well, and the crew's infrared film, used to provide complementary still images of fires investigated by MAPS, has been expended.

Controlled "line fires" in Ontario, Canada, were set as planned and observed by the crew in an effort to help calibrate the MAPS measurements.

These spaceborne radar images, produced regularly on a long-term basis, eventually could provide scientists with insight into movements of the Earth's surface as small as a fraction of an inch.

Such close monitoring may allow scientists to detect pre-eruptive changes in volcanoes and movements in fault lines that precede earthquakes, providing an early warning of imminent natural hazards.

Earlier this morning, Mission Specialist Dan Bursch took a break from his work to provide a television tour of the crew's orbital home office, explaining the shuttle's displays, controls, computers and cameras, as well as living accommodations.

The flight control surfaces will be tested using one of the hydraulic systems called an Auxiliary Power Unit, and ground station communications checks will be done.