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Planetary News: Mars (2005)

Mars Reconnaissance Orbiter: Team Reflects on Launch and Looks Ahead

"Flawless" was the word of the day at the Mars Reconnaissance Orbiter (MRO) post-launch press conference held at Kennedy Space Center in Florida earlier today.

"It feels great to be here," beamed Jim Graf, MRO project manager, of the Jet Propulsion Laboratory (JPL), which is managing the mission for NASA. "It's been a long road -- five long years to get here. Now, we're up and we're on our way to Mars. We have a spacecraft that is performing nominally. To an engineer," he added for the non-space oriented journalists on hand, "that means absolutely perfectly."

It was a far different story than yesterday, Graf confided. "Yesterday when we tried our launch attempt, everything seemed to go wrong, one problem after another. When I got up, about 1:30 in the morning, there was thunder and lightning and I said, 'Whoa -- this is not going to be a good day.' In contrast, today I got up and it was just exquisite. There were stars out, and [the launch preparations] just started smoothly, and it's been as smooth as silk all day. Everything has just gone flawlessly."

The MRO operations team in Florida began its day about four hours before the 7:43 a.m. (Eastern Daylight Time) lift-off, preparing the spacecraft for launch. "We loaded the proper configuration onto the vehicle, and basically at that point, we had to sit back and wait for the Atlas team to prep their vehicle," explained Howard Eisen, flight system manager, of JPL, who recounted the operations team's early morning activities. "About 45 minutes prior to launch, we started to get the spacecraft into its immediate launch state. We started to bring online systems that had been dormant. At launch -9 minutes, we started to remove safety inhibits and the spacecraft went on internal power. From that point on, we just sat back and watched a beautiful Atlas launch. As you can imagine we have a very, very happy team here in Florida, a very happy flight engineering team currently in Denver, and mission operations team in Pasadena."

One thing that was unique about the MRO launch is that the team was able to get the telemetry, to see what was going on with the spacecraft throughout the ascent, and to acquire continuous data through the Centaur stage of the rocket during the 58 minutes the spacecraft rode it.

There was only one brief incident that caused some concern. "We had four sensors that I believe were associated with the prop line, and one of them, which is located close to a heater that is mounted [near] that prop line, was showing a temperature that was [rising] a bit quicker than we had expected, primarily because the temperature that we had launched at [was] already higher than what we had been in tests," explained Kevin McNeill, MRO project manager at Lockheed Martin Space Systems.

The incident really didn't come as much of a surprise. In fact, it was something the team had considered, and, as a result, built in a failsafe mechanism should rising temperatures on those sensors rise too high. "The way the control spacecraft is set up it, it is controlling to the lower of the two temperatures until the higher temperature will trip a set-point that is programmed into the system," explained McNeill. "We watched it go up, and we were prepared to power-off the heater if we needed to, but as soon as that one sensor tripped over the set-point, [the spacecraft's mechanism] took over control, and the heater was turned off, and the result was that the temperature started to come back down. The spacecraft performed flawlessly and did exactly what it was supposed to."

Once MRO has separated from its Atlas rocket, the team did lose data for about two minutes, which was fully expected. "That's because the spacecraft was configuring it's telecommunications system. Then the Japanese station [at Tanegashima] picked us up, and from that point on, the spacecraft was on its own and providing us good information," said Eisen.

"Approximately one minute later, the spacecraft completed rate damping and began deploying its solar arrays," Eisen continued. "The initial solar array deployment was completed quickly and the vehicle began to move the solar panels into the position where they are all coplanar so we could point them at the Sun." At that point, the team also released and deployed the high gain antenna.

"All of these operations were completed within 20 minutes after launch, and they were completed in time for the initial acquisition of the spacecraft, which occurred at approximately 9:05 a.m. EDT," Eisen recounted. At that point, the spacecraft was power-positive and getting its own power through its solar arrays and communicating through the low gain antenna both to the Deep Space Network's Goldstone receiving station and to the Tanegashima receiving station, via the Japanese Space Agency (JAXA).

"We very quickly acquired stars on our star tracker, as well the Sun on our various Sun sensors and we were able to maintain a constant attitude from that point on," Eisen continued. "About 9:20 or so we were able to send our first command to the spacecraft and verify that it received it properly. So we are in full control of a completely healthy spacecraft."

"After we got through the poll of whole team, our SDLs - system design leads -said that this was the most nominal launch they can ever remember having been a part of," added McNeill.

Once two-way communications was established, the data started flowing in both directions. "We are downlinking at 32 k-bits, and uplinking at 2 k-bits per second, exactly as expected," confirmed McNeill. "We have a battery state of charge. The minimum state of charge we experienced was 99.5%. The only disappointment there from my power lead was that he wanted it to be over 100% the whole time, [yet] he figures this is probably the greatest stage of charge that we've ever had around separation. We are currently running 5.7 kilowatts on our solar arrays - we expected approximately 5.5 -- so they are performing slightly above what we had anticipated. We are tracking 8 to 9 stars right now and we have acquired attitude, and [a]ll of systems are nominal. Accordingly, everything is in the state we had expected."

Does it get any better?

Actually, it does.

"Our propulsion pressures are all nominal," McNeill continued. "We are currently running at 13% CPU utilization." [CPU stands for central processing unit and that, essentially, is the brain of the spacecraft's operating system, the most important element in the system.] "We have an incredible software product on an incredible command and data handling system, and, generally, when we are at this point of time, we are running 50, 60, 70% utilization -- to be running at 13% is fantastic." What that means is that the team will be able to "get down" all the data they want to when they get further into the mission.

MRO will spend the next 7 months in cruise, getting from Earth to Mars. "During that time, there are a lot of things we're going to be working on," informed Graf. "From a development point of view, we're going to be getting ready for the very critical Mars orbit insertion (MOI) burn, which will come up in early March, and the aerobraking phase that will follow that."

In the meantime, they are operating a spacecraft in flight. "That takes a lot of energy," Graf noted. "We'll be conducting calibrations of the science instruments and of the engineering subsystems as we go forward." During the coming weeks, the MRO team will be checking out the spacecraft, specifically "the health and performance of the subsystem on the spacecraft to make sure we have a good spacecraft," Graf said.

The plan calls for one early science event: MARCI [the Mars Color Imager camera that will eventually produce daily global images of Mars in six different colors in order to follow changes in weather] will look back at Earth and measure the ultraviolet radiation from Earth, so the team will have a comparison between Earth and the measurements that the instrument will make when MRO gets to Mars. The flight team will then put MRO through its first trajectory correction maneuver (TCM), Graf said, an 8-second burn of the six thrusters onboard, about 4 meters per second Delta D.

"After that, we will start checking out the instruments," Graf continued. "That will take us a couple of days, but we'll go through the whole sequence of all of the six instruments, plus the engineering payloads we have on board," he elaborated.

On September 8, MRO will go through its first lunar calibration. "We will actually slew the spacecraft across the Moon and around, so the optical instruments can view the Moon and get a good calibration of their sensors," explained Graf. "After that, on September 9, we will calibrate the high gain antenna, and then start in on some other calibrations. So it's going to be a very intensive time over the next three to four weeks, and it will stay that way as we go through acquiring more calibrations, performing more checkouts of the spacecraft, and getting ourselves ready for MOI."

As 'flawless' as everything went today, Orlando Figueroa, deputy associate administrator at the Science Mission Directorate at NASA headquarters in Washington D.C., cautioned the media: "It is important that we remember this is only the beginning," he said, as space agency officials are wont to do. "The launch is the first step. We have every reason to be proud. But we still have a few tense moments ahead of us on a long journey to Mars."

The first significantly critical time, of course, is the MOI burn. "We burn for about 30 minutes," said Graf. "We'll get under the south pole of Mars, and will be burning the main thrusters at that particular point in time, to take enough energy out of our trajectory so we can get captured by the Martian gravity." The most nerve-wracking thing is that only half of that maneuver will be seen by the team on Earth. "Once we slip behind Mars, we can't communicate anymore, so we'll be sitting in the control center for about 15 minutes just holding our breath until we get the information back," he explained. "That is the white-knuckle time, and it is for every mission that goes to Mars."

The second critical event, Graf continued, "only happens 512 times - [when] we will dip [and dip again and again] into the atmosphere during aerobraking, slowing ourselves down using the friction of the solar arrays and the high gain antenna against the molecules in the atmosphere." After those 512 dips, the spacecraft will drop its furthest point, the apoapsis, from Mars down from over 20,000 miles to about 200 miles, circularizing the orbit as it goes.

"That's where we will actually be performing our science orbit," Graf noted. "But each time we dip into the atmosphere [we] have to be very attentive, because if you dip into far, and you apply too much heat to the components and it can detrimental to the spacecraft. In addition, we have an atmosphere that we don't fully understand and that's the reason we're going to Mars is to understand all about it, including its atmosphere. If we get a dust storm and the atmosphere heats up, then we could be going in at a particular altitude, and envisioning one type of heating rate and [but getting] a different one. So we'll have to very attentive, and a lot of people will lose a lot of sleep."

While there are a number of other missions that have successfully aerobraked into more circular and less elliptical orbits, the maneuver is never a cakewalk. "We can do it, and we feel comfortable that this is something well within our ability, but it will certainly a very trying time for all of us," Graf confirmed. At the same time, the team does feel a certain amount of comfort in the fact that MRO was designed with aerobraking margins in mind. "Those margins will make us much more comfortable when we start doing this very dangerous activity."

"There are a number of things we designed into this system," added McNeill. For one thing, we've got an incredible surface area between the body of the vehicle, the solar arrays, and the high gain antenna to try to provide the surface area margin we need to survive the aerobraking. We thought about all these things and took steps to make sure they would be safe as possible."

Actually, MRO has the capability to actually survive a fault during MOI, "something we've not had on our spacecraft before," McNeill pointed out. "We have really tried to take a lot of the lessons learned from the past, those things where we recognize that these were periods of time where it is critical that everything operate in a particular manner, and tried to build in safeguards to make sure that everything works that much more safely than it has in the past."

If, for example, MRO encounters a sudden giant dust storm as Mariner 9 did in 1971, it has something never probably even imagine during the Mariner days -- a 'pop-up maneuver.' "We will be able to detect the dust storm from other instruments that are on the existing orbiting spacecraft and so the whole program is synergistic with one project and one spacecraft helping the other," Graf said. "If we really run into a problem and we see a bloom coming, we have our pop-up maneuver and we just jump in. We will have a round-the-clock monitoring of the spacecraft at that particular time both from our control centers and from the Deep Space Network and so we'll be able to take rapid action if we have too."

Graf, McNeill, Eisen, and Figueroa each acknowledged the companies and teams of people who contributed to making MRO fly so high today. It is a cast of hundreds -- from the mission team members from JPL and Lockheed Martin Space Systems; the Italian Space Agency, the University of Arizona, Ball Aerospace, Johns Hopkins University and its Applied Physics Lab (APL), Malin Space Sciences Systems, and JPL's instrumentation division and micro devices lab, each of which contributed to the science and engineering payloads onboard the spacecraft; the Kennedy Space Center folks and the International Launch Services Group (ILS) who worked the launch. And, a special nod was given to JAXA, "because they provided us the first indication that we had a safe and healthy spacecraft," and the much beloved Deep Space Network (DSN), "because without them no planetary mission would go anyplace," as Graf put it.

Last, but not least, the family members got their just due. "We had 1350 family and friends who wanted to be a part of this. They have lived this with us for four-and-a-half years, and we felt incredibly supported by them," McNeill said gratefully.