From: Bob Leif
To: Roger Racine et al.
"it is possible to write life-critical software in any language (Apollo
software was written in assembler). It just takes longer to integrate and
verify in some languages than in others."
In terms of mathematics and philosophy, you are correct. Under the same
rules, it is also possible for humans to do accounting by hand using base 16
or 2 or Roman numerals.
Since software development is engineering (hopefully) rather than science
(absolutely not), one has to include practical issues, such as code size and
cost. A figure of merit would be A(Cost)*B(Errors)/Code_Amount. Although, we
probably could not arrive on complete agreement on anything but cost. I
would venture to say that for anything over 10,000 lines of code, this ratio
would be at least 10 times higher for assembler than Ada. This is assuming
that the authors of both were competent in their languages. The measurement
of cost is easy; since, we leave it to the accountants. In short, how big
was the Apollo project? Would it scale to space station or any other major
From: Team Ada: Ada Advocacy Issues (83 & 95)
[mailto:[log in to unmask]]On Behalf Of Roger Racine
Sent: Thursday, November 09, 2000 6:31 AM
To: [log in to unmask]
Subject: Re: NASA X-38 Question
I was told by one of the NASA people that the slow roll was caused by the
wrong value being used for one of the flight control gains. It had nothing
at all to do with the programming language.
I have said it before, and I will say it again: it is possible to write
life-critical software in any language (Apollo software was written in
assembler). It just takes longer to integrate and verify in some languages
than in others.
At 10:29 AM 11/8/2000 , Robert C. Leif, Ph.D. wrote:
>From: Bob Leif
>To: Craig Spannring et al.
>I wonder how many billions the demise of the Ada Mandate will cost us. A
>previous, very expensive failure was the lack of separation of the
>antimissile warhead from the rocket. Was this the result of a software
>error? In what language is Star Wars II being programmed? I suspect that,
>present, the simulations are much more important than the media events. I
>believe that the chivalry shown by the US Defense Department in originally
>funding an excellent Ada compiler and ensuring its availability in its
>entirety to our enemies was excessive.
>From: Team Ada: Ada Advocacy Issues (83 & 95)
>[mailto:[log in to unmask]]On Behalf Of Craig Spannring
>Sent: Wednesday, November 08, 2000 12:11 AM
>To: [log in to unmask]
>Subject: Re: NASA X-38 Question
>Roger Racine writes:
> > At 02:01 PM 11/3/2000 , [log in to unmask] wrote:
> > >NASA's page on the recently tested X-38 crew return vehicle
> > >(http://www.dfrc.nasa.gov/PAO/PAIS/HTML/FS-038-DFRC.html) contains the
> > >following statement:
> > >
> > >"The X-38 flight computer is commercial equipment that is currently
> > >in aircraft, and the flight software operating system is a commercial
> > >already in use in many aerospace applications."
> > >
> > >Does anyone on this list have more details on the X-38 software that
> > >can share?
> > >
> > >F. Britt Snodgrass
> > VxWorks OS, application software is written in C.
> > Roger Racine
> >From comp.risks-
> Date: Mon, 6 Nov 1972 16:46:10 -0500 (EST)
> From: "James H. Paul" <[log in to unmask]>
> Subject: Unplanned roll in NASA's X-38
> *Aviation Week & Space Technology*, 6 Nov 2000, p. 24
> "NASA's X-38 Vehicle 131R did a slow, 360-deg. roll after release from
> B-52 carrier aircraft on Nov. 2. It was the first free flight of the
> vehicle, which automatically stabilized under the preprogrammed
> of a drogue chute and made a successful landing under parafoil on a dry
> lakebed runway, as scheduled, at Edwards AFB, Calif. The vehicle
> no damage in the test. Project officials said they would have to do
> trouble-shooting to figure out why the Crew Return Vehicle (CRV)
> rolled at an estimated average rate of about 20 deg. per sec. during its
> sec. of scheduled free flight. A software problem in the vehicle's
> control system was suspected, although project officials were also
> at whether aerodynamic disturbances immediately after separation might
> played a role. Actual separation from the B-52 was clean, and the
> control system maintained angle of attack throughout the 18-sec. roll.
> vehicle is an 80%-scale version of the CRV designed to provide emergency
> escape for International Space Station crews."