While the Mars Polar Lander team has relied on the work of previous NASA missions, a daring experiment that came along for the ride had to hoe its own row, the project manager said.

"Everything was tough. There was nothing easy on this project," explains Sarah Gavit, who heads up the Deep Space 2, or Mars microprobe, mission at Jet Propulsion Laboratory.

Just before the Mars Polar Lander slips into the Red Planet's atmosphere on December 3, the two Deep Space 2 microprobes are to be released. These probes, developed under NASA's New Millennium Program, are built to slam-dunk their way into Mars' frozen south polar surface.

Space.com caught up with Gavit to find out how she fared with her crash course in meeting Mars head-on.

Q: Are the probes ready to see action?

Gavit: We are in the dark for some eight hours after impact. The cruise to Mars has been very agonizing for me, personally, not having any data. The probes are powered off. So the only thing over time that could wear out would be the batteries, but that is a relatively minor risk. The bigger item is that if, for some reason the probes didn't work, we aren't going to have the telemetry data to be able to tell exactly what failed because we're in the dark for quite some time after impact.

Q: How tough was the challenge in designing a Deep Space 2 probe?

Gavit: To be honest with you, we didn't know ourselves whether everything was going to pan out. We had several technology hurdles to overcome. But we just worked away at it, one problem at a time. This is not a business for the fainthearted. You are living on the edge!

Q: What were the key issues that had to be solved?

Gavit: Two things we worried about the most. One issue was whether the probe could actually survive the high G-loads of impact. The part of the probe that goes into the surface could reach 30,000 Gs. The section of the probe that stays on top of the surface could see deceleration levels of 60,000 Gs. The second major worry was the reentry system. There's nothing to slow them down -- no parachute. By nature of their design -- their center of mass is really low -- they right themselves after they are deployed, like a badminton bird. As each probe hits, the aeroshell is pulverized and the probe splits into two, with a meter- (3.3 feet-) long cable connecting them.

Q: Anything that didn't make it on the probe, technology-wise?

Gavit: The telecommunications system. Trying to put all of it on a single chip. The technology was not ready. We could probably do it now, however.

Q: How far away from the lander do the probes land?

Gavit: About 60 kilometers (37 miles) away, to the north of the lander. The distance between the two probes is between one to 10 kilometers (6.2 miles) from each other.

Q: How long after impact would you know the probes have worked?

Gavit: The first pass overhead by Mars Global Surveyor, which picks up data from the probes, is 7 1/2-hours after impact. If we don't get a signal back right away, it doesn't mean failure. Conditions on the probe must be favorable to transmit, and that includes being warm enough. And it may take a couple of hours for us to get the data back, because we've got to then relay it back to the Deep Space Network. Also, the probes could come in at a slightly different angle, which means waiting for another Mars Global Surveyor pass overhead. But, if after two to three days we haven't heard anything, then probably it's a loss.

Q: Leaving you with what feelings?

Gavit: When they were launched, it's like watching your children go to college. You get emotionally attached. You put so much time in your life into something and they kind of have their own personality. When it works, it's the greatest thing in the world. When it doesn't, it's like losing your best friend. So I will have butterflies in my stomach from the wait. It's the waiting that drives you nuts. I'm just going to have to remind myself that I've waited a year and a half, and I can wait a few more hours.