It's nothing like childbirth, but building a spacecraft and watching it grow can bring about some joy, pain and suffering, said the team leader for NASA's prime contractor in charge of Mars Polar Lander.
"I could never quite hold back the tears," recalls Shane Roskie of Lockheed Martin Astronautics in Denver, Colorado. As the Mars Polar Lander lifted off atop a Delta 2 booster on Jan. 3, Roskie and his team were swept with emotion, not to mention the rocket's roar. Roskie has managed the assembly, testing and launch operations for the mission.
"Knowing that the lander was going to touch down on Mars, and to see the effort that the team put into the design, then build and test it ... that launch was extremely emotional," Roskie said.
Mars Polar Lander's diminutive size puts it in the cute and nearly huggable category.
But cramming together all the hardware and science gear to make a three-and-a-half foot tall lander, just 12 feet wide, was tough engineering. "You can't begin to imagine what we went through from a packaging standpoint," Roskie says.
Space.com talked with Roskie about his labor of love, the Mars Polar Lander.
Q: Is it appropriate to consider Mars Polar Lander as a miniaturized Viking?
Roskie: There is a lot of heritage there, drawing upon the work we did here on Viking as Martin Marietta, in conjunction with the Jet Propulsion Laboratory. We tried to stay on the coattails of what Viking did to develop this scaled down lander. Using the aeroshell, the parachute ... the entry and descent landing philosophy is very definitely similar to Viking.
The data and science capability of this spacecraft versus Viking is another matter. The technology has moved us so much further along. In terms of amount of data we can transmit back to Earth versus Viking, there's a substantial leap there.
Q: Cost wise, that's another leap too?
Roskie: Viking was well over $1 billion, and with the Mars Polar Lander you are looking at around $100 million. To be successful and give NASA what they would like to have, it was important to draw upon the development work on Viking.
With the resources and the funding the government has been able to put into these NASA planetary exploration programs, the challenges are horrendous. The money is not there to have as many resources on it today's engineers and scientists are faced with an incredible challenge.
Q: I suspect getting everything packaged in on Mars Polar Lander was difficult, correct?
Roskie: I can't remember how many meetings we had on packaging and design, trying to move things around to where we could get everything to fit. It was a team effort.
At first, everything was too big and didn't fit in the 2.4 meter (7.9 feet) aeroshell that protects the spacecraft during Mars entry. The lander legs were really difficult to get packaged in there. The antennas proved somewhat difficult too.
A lot of real estate was filled up on the lander by major components, like the solar arrays for power, propulsion system, attitude control sensors, the telecommunications system and the command and data systems.
The poor scientists wanted more science and wanted larger instruments. They had to compromise ... as did the spacecraft engineers and the people worried about thermal control ... everyone had to compromise in order to fit everything in.
Q: Just how tricky is the actual landing?
Roskie: Mars Polar Lander's radar will tell the spacecraft how far away the surface is and at what velocity the lander is traveling with respect to the surface.
How much thrust from the engines will then be determined onboard, to set the lander down on the surface. The engines will be cycling in about 100 millisecond pulses down to the terrain.
We actually have touchdown sensors in each of the three legs. When those legs touch, then the guidance system senses we have touchdown and cuts the engines off.
Q: How much abuse can the lander take on touchdown, particularly if the terrain is rocky?
Roskie: The legs are kind of a combination of shock absorbers as well as being crushable too. Say, if one of the three legs hits a small rock, it can absorb the shock and actually crushes. The crushable leg elements are designed to crush a total of about 9 inches.
In a nominal crush, which is we believe about four-and-a-half inches of the legs, we can clear about a 30 centimeter rock.
Q: How do you scale the difficulty of what Mars Polar Lander will attempt to do?
Roskie: This is not like putting up a communications satellite, which the public now considers as commonplace.
They need to understand the extreme complexity of this lander mission. In some cases, it's almost as complicated as an Apollo mission to get the lunar lander down.
Mars Polar Lander comes into the atmosphere at about 10,500 miles per hour. Within five minutes you've got to do all the separations and deployments, lock your radar onto the surface, have the engines provide the right thrust and get the spacecraft to touch down at 5 miles per hour.
This is space exploration. It is not communications satellite business.
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