July 27, 1999 - Columbia touched down at the Kennedy Space Center on runway 33 at 11:20 p.m. EDT completing the first mission with a female Commander at the helm.

July 26, 1999 - Columbia's crew began packing up experiments today and preparing to return to Earth tomorrow with a touchdown planned on the Kennedy Space Center's shuttle runway in Florida at 10:20 p.m. CDT. Commander Eileen Collins and Pilot Jeff Ashby checked out the shuttle's cockpit instruments, displays and flight control systems this evening as part of the preparations for landing. They also test-fired Columbia's 38 small steering jets, finding everything in good shape and ready for the trip back to Earth.

July 25, 1999 - The day started off with a wake-up call sent up in honor of Pilot Jeff Ashby. It was a song called "Some Day Soon," written by Judy Collins and performed by Suzy Boguss.

Mission Operations' Wayne Hale reported that engineers on the ground continue to evaluate the slightly reduced performance of the main engines. The right engine's reduced performance may have been due to a small hydrogen leak in tubes that help cool the nozzle. While it won't be confirmed until the shuttle returns to Earth, Hale said the evidence pointing to the leak includes a slightly higher than normal temperature in that engine, and launch photos showing a white streak that could be escaping hydrogen.

July 24, 1999 - Commander Eileen Collins, Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini were awakened at 6:31 p.m. EDT with the song "Brave New Girls," performed by Teresa. Hawley, the resident astronomer of the STS-93 crew, will continue his work with the Southwest Ultraviolet Imaging System, or SWUIS instrument, to collect imagery of targets associated with Mercury, Venus, Jupiter and the Moon.

July 23, 1999 - The third time was a charm. The Space Shuttle Columbia blasted off on its third try to carry five astronauts to orbit for the long-awaited deployment of Chandra X-Ray Observatory, which will peer into previously invisible mysteries of the universe.

At 7:47 a.m. EDT, the STS-93 crew successfully deployed the massive Chandra X-Ray Observatory from Columbia's payload bay. Chandra is now enroute to its new orbit taking it one-third of the way to the Moon.

July 22, 1999 - The launch of Columbia was scrubbed due to thunderstorms in the Kennedy Space Center area.

July 20, 1999 - A rare launch abort occurred within 7 seconds of lift-off when a high level of hydrogen was detected in the aft engine compartment. The hydrogen level momentarily spiked and then returned to an acceptable level. The orbiter's hazardous gas detection system indicated a 640 ppm concentration of hydrogen in Columbia's aft engine compartment, more than double the allowable amount. System engineers in KSC's Firing Room No. 1 noted the indication and initiated a manual cutoff of the ground launch sequencer less than one-half second before the Shuttle's three main engines would have started. Standard safing operations followed immediately. The safety of the flight crew and orbiter were not compromised at any time. The astronauts returned to the KSC crew quarters.

Following preliminary system and data evaluation, launch managers are confident that the hydrogen concentration indication was false and are proceeding with a 48-hour scrub turnaround plan. A complete review of the Shuttle's main propulsion system and related sensors is being conducted today, but managers have already determined that the hydrogen concentration was actually about 114 ppm. This measurement is within allowable limits. The launch has been rescheduled for Thursday at 12:28 a.m.

Because the external ignitors at Launch Pad 39B were ignited, KSC technicians must replace them over the next two days. These ignitors burn-off the hydrogen concentration outside the orbiter, near the Shuttle main engines. The Chandra X-ray Observatory will remain powered up inside the orbiter and will not be adversely affected by the scrub. Eight middeck payloads will be removed, reserviced and installed back inside the orbiter during the down period.

Overview - The primary objective of the STS-93 mission is to deploy the Advanced X-ray Astrophysics Facility. AXAF is the most sophisticated X-ray observatory ever built. It is is designed to observe X-rays from high energy regions of the universe, such as hot gas in the remnants of exploded stars. This facility was recently renamed the Chandra X-Ray Observatory in honor of the late Indian-American Nobel Laureate Subrahmanyan Chandrasekhar. "Chandra" also means "Moon" or "luminous" in Sanskrit.

The Observatory has three major parts: (1) the X-ray telescope, whose mirrors will focus X-rays from celestial objects; (2)the science instruments which record the X-rays so that X-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work.

Other payloads on STS-93 are the Midcourse Space Experiment (MSX), Shuttle Ionospheric Modification with Pulsed Local Exhaust (SIMPLEX), Southwest Ultraviolet Imaging System (SWUIS), Gelation of Sols: Applied Microgravity Research (GOSAMR), Space Tissue Loss - B (STL-B), Light Weight Flexible Solar Array Hinge (LFSAH), Cell Culture Module (CCM), and the Shuttle Amateur Radio Experiment - II (SAREX - II), EarthKam, Plant Growth Investigations in Microgravity (PGIM), Commercial Generic Bioprocessing Apparatus (CGBA), Micro-Electrical Mechanical System (MEMS), and the Biological Research in Canisters (BRIC).

The Midcourse Space Experiment (MSX) payload will require orbiter thruster firings to be used as a sensor calibration and evaluation target for the space-based ultraviolet, infrared, and visible sensors on the MSX satellite. The satellite will be in an approximately 560 nautical mile, 99 degree inclination orbit.

The objective of Shuttle Ionespheric Modification with Pulsed Local Exhaust (SIMPLEX) payload activity is to determine the source of Very High Frequency (VHF) radar echoes caused by the orbiter and its OMS engine firings. The Principal Investigator (PI) will use the collected data to examine the effects of orbital kinetic energy on ionospheric irregularities and to understand the processes that take place with the venting of exhaust materials.

The Southwest Ultraviolet Imaging system (SWUIS) is based around a Maksutov-design Ultraviolet (UV) telescope and a UV-sensitive, image-intensified Charge-Coupled Device (CCD) camera that frames at video frame rates. Scientists can obtain sensitive photometric measurements of astronomical targets.

The objective of the Gelation of Sols: Applied Microgravity Research (GOSAMR) experiment is to investigate the influence of microgravity on the processing of gelled sols. In particular, the purpose is to demonstrate that composite ceramic precursors composed of large particulates and small colloidal sols can be produced in space with more structural uniformity. It will also show that this improved uniformity will result in finer matrix grain sizes and superior physical properties.

The focus of Space Tissue Loss - B (STL-B) is direct video observation of cells in culture through the use of a video microscope imaging system with the objective of demonstrating near real-time interactive operations to detect and induce cellular responses.

The Light Weight Flexible Solar Array Hinge (LFSAH) payload consists of several hinges fabricated from shape memory alloys. Shape memory deployment hinges offer controlled shockless deployment of solar arrays and other spacecraft appendages. LFSAH demonstrates this deployment capability for a number of hinge configurations.

The objectives of the Cell Culture Module (CCM) are to validate models for muscle, bone, and endothelial cell biochemical and functional loss induced by microgravity stress; to evaluate cytoskeleton, metabolism, membrane integrity and protease activity in target cells; and to test tissue loss pharmaceuticals for efficacy.

The Shuttle Amateur Radio Experiment (SAREX-II) demonstrates the feasibility of amateur short-wave radio contacts between the shuttle and ground-based amateur radio operators. SAREX also serves as an educational opportunity for schools around the world to learn about space by speaking directly to astronauts aboard the shuttle via ham radio.

The EarthKAM payload will conduct Earth observations using the Electronic Still Camera (ESC) installed in the overhead starboard window of the Aft Flight Deck.

The Plant Growth Investigations in Microgravity (PGIM) payload experiment will use plants to monitor the space flight environment for stressful conditions that affect plant growth. Because plants cannot move away from stressful conditions, they have developed mechanisms that monitor their environment and direct effective physiological responses to harmful conditions.

The Commercial Generic Bioprocessing Apparatus (CGBA) payload hardware allows for sample processing and stowage functions. The Generic Bioprocessing Apparatus - Isothermal Containment Module (GBA-ICM) is temperature controlled to maintain a preset temperature environment, controls the activation and termination of the experiment samples, and provides an interface for crew interaction, control and data transfer.

The Micro-Electrical Mechanical System (MEMS) payload examines the performance, under launch, microgravity, and reentry conditions of a suite of MEMS devices. These devices include accelerometers, gyros, and environmental and chemical sensors. The MEMS payload is self-contained and requires activation and deactivation only.

The Biological Research in Canisters (BRIC) payload was designed to investigate the effects of space flight on small arthropod animals and plant specimens. The flight crew will be available at regular intervals to monitor and control payload/experiment operations.