To the moon on a pocket calculator

In article ,
quilty wrote:
I heard (and don't ask me to identify the source...because I can't
quite remember where I heard this) that pocket calculators today are
more powerful than the computers that sent the Apollo crews to the
moon in the 60s.

That is more or less correct. Digital electronics has advanced
enormously in the last four decades.

If this is true...why the need for such complicated machines like the
Shuttle?

Because faster computers do very little to solve the engineering problems
of spaceflight. Computing power was not a major limitation on Apollo.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

In article ,
Ami A. Silberman wrote:
2. The real computing brains behind Apollo were earth-bound. All the
trajectory and burn calculations were performed on earth.

This is true, but Apollo also had the capability of doing a credible job
on board. In fact, the original requirement on the Apollo navigation
system was to fly the entire mission with zero help from the ground, and
it was very nearly capable of that. (The ability to actually fly the
lunar landing that way was sacrificed when they ran short of memory,
because by then it was clear that on-board navigation would be only a
backup system, and so only the abort cases really had to be covered.)

3. Compared to Apollo, the Shuttle flies a much more complicated
re-entry profile. (Since it actually flys, as opposed to plummets
aerodynamically.)

Apollo flew too, although less obviously. It had significant lift at
hypersonic speeds, and that was used to control the reentry. The shuttle
reentry profile is slightly more complex, but only slightly.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

I was reading in the bathroom when I ran across an item written by
"Ami A. Silberman" on Thu, 24 Jul 2003 15:36:45
-0400, which said:

5. The original shuttle computer was about as powerful as a late 70's
PC.

*Were* there PCs in the late '70s? I honestly don't remember. I know
there weren't in the late '60s and early '70s.

Hmm... Thinking hard, I remember that the late '70s were the time of
the Atari game consoles, and I remember reading an article (Time?
Newsweek?) that speculated whether Ataris might be adaptable so that
people could have computers in their homes. I think that article
appeared about 1980 or '81. It was also in 1980 that I saw my first
desktop computer, in the USCG base hospital on Kodiak, AK.


---------------
Beady's Corollary to Occam's Razor: "The likeliest explanation of any phenomenon is almost always the most boring."

"John Beaderstadt" wrote in message
...
I was reading in the bathroom when I ran across an item written by
"Ami A. Silberman" on Thu, 24 Jul 2003 15:36:45
-0400, which said:

5. The original shuttle computer was about as powerful as a late 70's
PC.

*Were* there PCs in the late '70s? I honestly don't remember. I know
there weren't in the late '60s and early '70s.

Hmm... Thinking hard, I remember that the late '70s were the time of
the Atari game consoles, and I remember reading an article (Time?
Newsweek?) that speculated whether Ataris might be adaptable so that
people could have computers in their homes. I think that article
appeared about 1980 or '81. It was also in 1980 that I saw my first
desktop computer, in the USCG base hospital on Kodiak, AK.


Here are a couple of interesting links:
http://www.darron.net/firstibm.html (IBM got into the PC business in 1981,
until then it was dominated by Apple and Tandy.
http://www.apple-history.com/frames/?
Apple I and II were introduced in 1976 and 1977. So yes, there were PCs in
the late 1970s.

Jason

John Beaderstadt wrote:
*Were* there PCs in the late '70s? I honestly don't remember. I know
there weren't in the late '60s and early '70s.

Yep. I built my Altair 8800 the summer of '75. IIRC the first IBM
PC was out in 1980. Useful microcomputers were very much around
in the late 70's.

Sam Seiber

In article ,
quilty wrote:
I heard (and don't ask me to identify the source...because I can't
quite remember where I heard this) that pocket calculators today are
more powerful than the computers that sent the Apollo crews to the
moon in the 60s.



http://www.hpcalc.org/hp48/docs/columns/space.html



HP-65 IN SPACE


"65 Notes," July 1975
Volume 2, Number 6, Page 7

PALO ALTO, Calif., July 8 -- An 11-oz, $795 pocket calculator that can
be programmed like a computer will play an important role in the
historic Apollo/Soyuz rendezvous in space July 17.

The Hewlett-Packard HP-65 fully programmable pocket calculator will be
used to calculate two critical mid-course correction maneuvers just
prior to the linkup of the U.S. Apollo and the Russian Soyuz
spacecraft. These maneuvers will take place 12 and 24 minutes after
terminal phase initiation (the beginning of the last part of the
flight before rendezvous).

The calculator also will be used as a backup for Apollo's on-board
computer for the final maneuvers prior to rendezvous and docking. The
first use will be for the coelliptic maneuver (putting both spacecraft
into the same orbit) when the vehicles are within approximately 100
miles of each other. The second will be for the terminal phase
initiation calculations when Apollo is 22 miles from Soyuz. In both
instances, the HP-65 will be used to solve the problems, and its
answers will be compared with those of the on-board computer.

In the event of an on-board computer failure, however, the HP-65 will
provide the only available solution for the mid-course maneuvers,
since the spacecraft will not be in communication with ground stations
at that phase of the mission.

A third set of calculations to be performed by the battery-powered
HP-65 will allow the astronauts to precisely point Apollo's high gain
antenna at an orbiting satellite to assure proper communications with
Earth.

NASA scientists have written programs of up to 1,000 steps and
recorded them on tiny magnetic cards (100 steps per card). The
astronauts will feed these cards into the HP-65 to automatically
perform the critical calculations. In previous space flights, backup
maneuver calculations were made manually, using charts. The HP-65 will
substantially reduce the time needed to make the complex calculations
and improve the quality, accuracy and confidence in resulting
solutions.

Two HP-65s will be taken on the space flight, along with four sets of
program cards and six spare battery packs.

The HP-65 is not the first HP pocket calculator to venture into space;
an earlier model, the HP-35, went along on the Skylab missions.

The HP-65 is a general purpose calculator that can be programmed to go
through a step-by-step routine at the touch of a few keys, solving
extremely complex, lengthy or repetitive calculations quickly, easily
and accurately. Users can write their own programs for the calculator
or buy prerecorded program cards from Hewlett-Packard in the fields of
finance, mathematics, statistics, electrical engineering,
thermodynamics, stress analysis, surveying, medicine, aviation and
marine navigation.

Hewlett-Packard pocket calculators are no strangers to adventure. They
have served high upon the rugged slopes of Mt. Everest; at the LeMans,
France, professional auto races; at the navigator's station of the
sailboat "Courageous" the successful America's Cup defender; and in
the cockpits of Powder Puff Derby aircraft race contestants.

The U. S. spaceship will begin its mission July 15 from Cape
Canaveral.






--
Rusty Barton - Antelope, California |"Every so often, I like to
| stick my head out the window,
| look up, and smile for the
| satellite picture."-Steven Wright

In article ,
John Beaderstadt wrote:
*Were* there PCs in the late '70s? I honestly don't remember. I know
there weren't in the late '60s and early '70s.

In the modern sense of the term, no. But the first personal computers
started appearing circa 1975, and I believe the first issue of Byte hit
the stands in 1976.

Mind you, it was a very different world -- the machines were very small
and limited, a floppy drive was a luxury, hard drives were unheard-of, and
the early Byte was essentially a specialized electronics magazine, heavy
on circuit diagrams and construction articles. (In fact, Byte was started
by the publisher of a ham-radio magazine.) Things changed quickly.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

In article ,
Rusty Barton wrote:
Hewlett-Packard pocket calculators are no strangers to adventure. They
have served high upon the rugged slopes of Mt. Everest; at the LeMans,
France, professional auto races; at the navigator's station of the
sailboat "Courageous" the successful America's Cup defender; and in
the cockpits of Powder Puff Derby aircraft race contestants.

Alas for the days when HP made the world's finest calculators and
everyone knew it... How the mighty have fallen.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

In article , says...
In article ,
quilty wrote:
I heard (and don't ask me to identify the source...because I can't
quite remember where I heard this) that pocket calculators today are
more powerful than the computers that sent the Apollo crews to the
moon in the 60s.

That is more or less correct. Digital electronics has advanced
enormously in the last four decades.

If this is true...why the need for such complicated machines like the
Shuttle?

Because faster computers do very little to solve the engineering problems
of spaceflight. Computing power was not a major limitation on Apollo.

Well -- yes and no. Computing power was not an issue the way Apollo was
flown, and since there were never any major communication problems, it
was fine to have the ground calculate all the burns and trajectories.

However, there *was* a program called RTE (Return to Earth) that was
developed for Apollo and ultimately removed because there simply was not
room in memory for it and for the other programs needed. That program
would, indeed, have allowed a crew to calculate its own trajectory and
burns to return to earth at any point during the mission, from five
minutes after TLI through lunar orbit through post-TEI.

So, there *was* some capability that was originally desired for Apollo
that couldn't be provided because of limitations in computing power.

--

It's not the pace of life I mind; | Doug Van Dorn
it's the sudden stop at the end... |

In article ,
says...

snip

Here are a couple of interesting links:
http://www.darron.net/firstibm.html (IBM got into the PC business in 1981,
until then it was dominated by Apple and Tandy.
http://www.apple-history.com/frames/?
Apple I and II were introduced in 1976 and 1977. So yes, there were PCs in
the late 1970s.

Yep, there were Apple and TRS-80 computers in the late '70s. There was
also the Commodore machine, I think that debuted in 1979, but I'm not
positive.

I worked for Arthur Andersen in 1981, for the Computer Aids to Tax
Practice group, and our partner-in-charge was determined to place a
personal computer on every tax professional's desk. So we made the first
large order (several thousand) for IBM PCs that IBM ever received. I got
an original IBM PC, with DOS 1.0 (complete with the floating point math
error) and two 5.25 floppy disk drives, in 1981. 8088 processor. We
developed applications in BASIC and VisiCalc for a couple of years to
calculate various tax figures.

That's where I got real good at playing with DOS. Those days are long
gone, of course -- as is Arthur Andersen, which is still amazing to me.
It used to be that having AA&Co. on my resume got me immediate attention.
Now, I think it's one of the reasons I don't even get responses when I
send out my resume... *sigh*...

--

It's not the pace of life I mind; | Doug Van Dorn
it's the sudden stop at the end... |