TES NEWS, Volume 5, Number 4, December 1996

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Mars Global Surveyor -- Espectrómetro de Emisiones Térmicas (TES) -- MGS Delta II Launch

Mars Global Surveyor and TES are On Their Way!

by Greg Mehall, TES Systems Engineer, ASU, November 16, 1996

On To Mars!

Mars Global Surveyor (MGS) was launched aboard a Delta II rocket at 12:00:49 p.m. Eastern Standard Time (EST) on November 7, 1996. Onboard the spacecraft is the Thermal Emission Spectrometer (TES), an instrument conceived by ASU Geology professor Philip Christensen to map the minerals on the surface of the Red Planet. A little more than three years (and a lot of careful work) after the tragic loss of Mars Observer (which also carried a TES), we are once again headed back to Mars.

I have been spending a lot of time over the past three months down at the Kennedy Space Center in Florida. I was busy helping prepare MGS and our instrument for launch. Of course, the most fun was the day we actually launched. Most of the MGS TES group from Arizona State University came to Florida to watch, although a few of our people stayed in Arizona so that folks in the Phoenix area could visit our lab and see the launch on NASA-TV.

Wrapped in Golden Blankets, Fueled, and Weighed.

After MGS arrived at the Cape Canaveral on August 14, the spacecraft was transported to a clean room at the Payload Hazardous Servicing Facility (PHSF) at the Kennedy Space Center (KSC). The final preparations of MGS included the testing of the spacecraft and science instruments before being transported to the launch pad to be loaded into the Delta II launch vehicle. The main purpose of these tests was to verify that the spacecraft and its subsystems were not damaged during shipment from Lockheed Martin in Denver, Colorado, to KSC.

The final stages of the spacecraft assembly were also performed at the PHSF. This included installing the gold mylar thermal blankets that cover most of the spacecraft. The blankets keep the spacecraft warm in the cold of outer space. After blanketing was completed, the propulsion system was tested, then fuel was loaded into the MGS tanks and a final weight measurement was made to ensure the MGS mass did not exceed the launch capability of the Delta rocket. The final mass of the fueled MGS spacecraft at launch was ~1060 kg (2,337 lbs.). After fueling was completed, the science instruments were inspected and cleaned one last time. Then the Delta third stage solid rocket motor was brought into the PHSF clean room and the MGS spacecraft was connected to the top of it.

Over to Delta's Pad.

On October 22, the MGS and third stage "stack" was taken on a truck out to Space Launch Complex 17A (SLC-17A). Once at SLC-17A, the spacecraft and third stage were hoisted up to the top of the MGS Delta II rocket. The Delta II had been assembled over the previous couple of months by McDonnell Douglas. The Delta II consists of a first stage liquid rocket, a second stage liquid rocket, nine solid rocket motors attached to the first stage, and the third stage solid rocket that is connected to the spacecraft. The fully assembled and fueled MGS Delta rocket stood ~40 meters (130 ft.) tall and weighed ~231,300 kg (509,924 lbs.).

Inside view of the Delta II Rocket that was used to launch Mars Global Surveyor November 7, 1996.

Launch Preparations at the Pad.

Once on the pad, the MGS spacecraft and instruments went through one more round of testing to ensure they survived the move from PHSF. Before the payload fairing (rocket nose cone) was installed, the final red-tag items, or "remove before flight" protective components, were removed from the spacecraft and instruments. The two large clam-shell fairing covers were then hoisted into position and brought together around the spacecraft and third stage; then they were attached to the top of the second stage of the Delta rocket. On October 31, the MGS spacecraft was ready for launch-- all that remained were the final preparations and fueling of the Delta II.

Delta II carrying Mars Global Surveyor as it ascends over the Atlantic Ocean on November 7, 1996. NASA Photo.

Up, Up, and Away!

The first launch opportunities were on November 6th at 12:11 p.m. EST and 1:15 p.m. EST. Due to heavy cloud cover and strong winds high in the atmosphere, both opportunities were scrubbed and we had to wait until the next day. Luckily, the following day's weather brought perfectly clear skies.

At 12:00:49 p.m. EST on November 7, the MGS and Delta launch vehicle were cleared for lift-off by mission control. The rockets ignited. Much to the excitement of the hundreds gathered to watch, the Delta II, its engines spewing a trail of flames, rose slowly from the pad in a large cloud of smoke.

Nice View from "The Cape".

A few seconds later, the rumble of the Delta's engines could be heard clearly at our viewing site as the rocket went quickly upward and to the east. About one minute after lift-off, six of the nine small solid rocket motors burned out and fell away and the remaining three were ignited. From the viewing site we could clearly see the trail of smoke from the 6 jettisoned rockets. One minute later the final 3 solid rocket motors burned out and separated from the accelerating rocket. Two and half minutes later, the first stage main engine turned off, the first stage was jettisoned, and the second stage engine was ignited. When these events occurred, the rocket was at an altitude of 71 miles and was 336 miles down range from the launch site. At this point the drag from the Earth's atmosphere is no longer a problem so the spacecraft's fairing (nose cone) was jettisoned. The second stage burned for about 5 minutes, putting MGS in a parking-orbit about 115 miles above Earth.

Leaving Earth's Gravity Well.

MGS then coasted for about 30 minutes before reaching the proper position to begin the "two-burn trans-Mars injection sequence". At this point, the second stage engine was re-ignited and burned for approximately two minutes. The Delta then coasted for about one minute before dropping the second stage. During this time, small rockets attached to a spin table at the base of the third stage were fired in order to spin the third stage and the spacecraft to a rate of 60 RPM. This spinning is required to give the third stage stability when its engine is ignited. The third stage burned for one and half minutes, allowing the spacecraft to leave the influence of Earth's gravity and head out toward Mars. After this burn, the MGS spacecraft was traveling at nearly 25,000 miles per hour. Approximately 4 minutes after the third stage finished its burn, a yo-yo cable device was deployed to despin the spacecraft; and then the third stage was jettisoned.


Mars Global Surveyor Time Line

Deploying the Solar Panels.

Following separation from the third stage, the MGS spacecraft automatically opened up its two solar arrays and pointed them toward the Sun in order to start generating electricity. During the launch, the spacecraft was running on internal batteries. This event was very critical since the spacecraft can only operate on battery power for a limited amount of time. After the solar panels were deployed and pointed at the Sun, MGS was programmed to turn on its transmitter and "phone home". This occurred about an hour and ten minutes after lift-off. MGS was on its way!

This was an important event because it verified that the critical spacecraft systems survived the violent conditions experienced during the launch. However, engineers at Lockheed Martin discovered that one of the solar arrays did not deploy completely. Apparently, the hinges that connect one of the two solar panels to the spacecraft jammed at about 20 degrees short of the full, locked position.

Dealing With Solar Panel "Glitch."

The MGS team at Lockheed Martin is currently studying the solar panel problem. The team is planning strategies to deal with the problem, including the design of contingency plans in case no solution can be found. The solar panels are generating sufficient power and pose no risk to cruise operations, but the engineers are a little concerned that the solar panel problem may complicate the aerobraking activities that occur after the MGS spacecraft goes into orbit around Mars. The severity of this problem should be better understood by mid-December. Despite this problem, all of the other spacecraft subsystems seem to be operating as expected.

Coming Up: Parting Shots of the Earth. The next step for the MGS is to perform science instrument checkouts. The instruments are scheduled to be turned on just before Thanksgiving (U.S. holiday, November 28) and will be tested for a few days. During these checkouts, the spacecraft will perform several maneuvers that will point the instruments back at the Earth. This will allow the instruments to use Earth as a target for their checkouts. The Mars Orbiter Camera should take some nice images of Earth. The TES will also view the Earth during its checkout but will not be able to generate images due to the large distance from the Earth. TES will use Earth as a point source of thermal energy to map out the field of view of its three detector arrays. This is a perfect opportunity for us to check the "health" of TES after the violent vibrations experienced during launch.

Everyone on the MGS project is excited about the successful launch of the MGS spacecraft and the start of its long journey to Mars. We anxiously await its rendezvous with the Red Planet and successful Mars Orbit Insertion (MOI) on September 12, 1997.

I will update you on the spacecraft and instrument cruise activities during the 10 month cruise to Mars in future editions of the TES News. Until then ... To Mars!!

Back to Contents of TES News December 1996