They did what? Well, at least we now know why the other one vanished of the face of the err, planet:

java.lang.IndexOutOfBoundsException
    at java.io.FileInputStream.readBytes(Native Method)
    at java.io.FileInputStream.read(FileInputStream.java:183)
    at sun.misc.Resource.getBytes(Resource.java:67)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
    at com.ooc.CORBA.Request.marshal(Request.java:432)
    at com.ooc.CORBA.Request.invoke(Request.java:258)
    at gov.nasa.RadarChannel.receiver(Packet.java:716)
    at pod.bay.door.open(HAL.java:939)
[download]

Yeah, I know it's a cheap shot, I should really be posting on slashdot...

However, Java is not on the Mars rover(s). It was used to write the Science Activity Planner software, used at JPL to plan rover activities.

The rovers use VxWorks, a very robust real-time OS. More details about their hardware and software systems can be found here and here.

I don't think anyone in their right mind would deploy Java, Perl, or Python that far from home, at least not for any kind of mission-critical use. All 3 are way too complex to trust as reliable in that kind of environment.

I don't think anyone in their right mind would deploy Java, Perl, or Python that far from home, at least not for any kind of mission-critical use. All 3 are way too complex to trust as reliable in that kind of environment.

That's hogwash. Dr. Paul Backes, Technical Group Leader at Jet Propulsion Lab:

In 2001 and beyond, scientists will use Java to relay command sequences to a remote rover on Mars, just as schoolchildren and other Internet visitors are doing in the simulation today. But will Java ever be embedded in the actual devices deployed to outer space? "Yes, I can imagine using Java for rovers and spacecraft," says Paul. "I think it is inherently a safer language than C and C++, which is very important for spacecraft."