An indicator that I should go into this business was that I figured
out in second grade the true scale of the solar system. For our 12 inch
globe at home I calculated that it should be two and a half miles,
two and a half miles, to the sun. Living in Henrietta, Texas
at the time, that was out in a cow pasture on the other side of the
tracks where dad and I used to fly free-flight models, and that was
just the tiny inner solar system. Neptune / Pluto, at 30 astronomical
units would be more than 75 miles away, most of the way to Dallas!
So, I said, well, OK, what if the earth was the size of a BB? Still,
the earth-sun distance, much less the solar system, would not fit in
the house, it would barely fit on the block we lived on with house and
church on it and the sun itself was still much more than basketball
sized. Holy Cow!
Later, during the Apollo missions, I would put my 12” globe in
one room and a softball for the moon 30 feet down the hall in another
room, scale distance away. And when they would announce on the radio
how far away the mission was, I’d calculate and measure and put
my CSM/SM/LEM model, in proper configuration for the current flight
phase, at that location, understanding, of course, that the model
itself wasn’t to scale.
A few years ago, a fellow named Overstreet wanted to demonstrate
this same 'enormity of the solar system' concept, noting that nothing
published about the solar system or even the earth moon is, or can
easily be, "to scale." See
Overstreet is right. We, including JPL, never represent the solar
system, or outer space at all for that matter, correctly because
it’s just impossible to do in a TV-aspect-ratio or
figure-in-a-book world. And this leads to all sorts of problems dealing
with newcomers to the business. “Oh we can just run over to Mars,
it’s ‘in the neighborhood’.” One of my most
common refrains is, “You have no idea how big space really is, it
is incredibly huge and, luckily, very empty.”
But, if you think about it, your experience just looking at the sky
at night verifies this. Jupiter is not a big hunk the size of a tree
hanging there like you’d think if you believed our pictures on
TV. It’s a bright spot that you need a pretty good telescope to
see with more than one pixel resolution. All the planets, all the
stars, all the every things in the sky are that way, which is why we
can be here at all. We can be here at all because the vast emptiness
means that we don't collide much, most collisions in our neighborhhod
having cleaned up local space "long" ago, "long" in human occupancy on
the planet terms.
The only objects in the sky that are not single pixel points to the
unaided eye are the sun and the moon. But, indeed, even the moon (and
the sun) take up only five one millionths of the sky, as we EMErs know
all too well! If the entire (four-pi steradian) sky were $10,000, the
sun and moon would be about a nickel each.
While I was in second grade figuring all this out for the first
time, JPL was taking the first steps to send spacecraft to Mars:
Mariner Art:
This is the first spacecraft picture of Mars ever received on
earth. Arriving at 8.3 bits per second, the guys printed out the data
as numbers on slips of paper, then colored each number according to its
value, then carefully glued the stips together. "Real" pictures were
made by computers later, but this was the first.
Things on my resume that I won't detail here:
Telecom for the Mars Helicopter
GPS Waveforms for CoNNeCT -
The Low Mass Radio Science Transponder - Satellite (LMRST-SAT)
concept:
So one day at lunch Jim Lux (W6RMK) said we should do a CubeSat mission
on B & P (Bid and Proposal) money (a few $10K) and suggested that
RSTI (Radio Science Transponder Instrument) needed a TRL (Technology
Readiness Level) raising ride.
I took the idea and proposed to the DRDF (Director's Research and
Development Fund) to do this in partnership with the Space Systems
Development Lab (SSDL)at Stanford
University, asking for $200K. They gave me $175K we built a 2U CubeSat
that could be flown. The DRDF money only buildt the spacecraft, it
didn't get it flight tested or launched. Part of what you are supposed
to do on DRDFs is to go get money for "follow on" work which, in this
case would be environmental testing, launch, and space operations.
ATLO. I don't have that yet, but am working on leads. We may have a
launch in summer 2012.
Matt Dennis and I built"flight" unit in part on some of the RSTI
development money, which was a big relief.
So, we can't really do it on B&P money, but we're within an order
of magnitude so far.
Somehow, in the original proposal process, the name got changed from
RSTI to LMRST (Low Mass Radio Science Transponder). The kids at
Stanford started calling it "LMRST Sat" pronounced "Elmer Sat." Funny
connection back to ham radio there, but when I went to Stanford for a
meeting and I was older than any two of the other people in the room
put together, I thought it would take too much explaining to make the
quip. Maybe later in the project.
Yeah, I guess I'm the "Elmer" now....
LMRST-Sat (a later incarnation from the one shown here) was launched
from Vandenburg October 8, 2015, was known to have been deployed, but
was not successfully contacted on UHF and so was deemed a failure.
GRAIL
I'm in the Tracking Systems and Applications organization where I work
mostly on GRAIL
GRAIL sends two spacecraft to the moon, like GRACE
sent two spacecraft to the earth. The two spacecraft orbit close to
their planet and measure the distance between themselves to microns
(millionths of a meter) as they go. From this information the precise
gravitational structure of the planet can be inferred. For GRACE at
earth, the measurements are so precise that seasonal changes in the
water table can be detected, along with other gravitational phenomena
like mountain ranges and deep sea trenches. At the moon the goals are
to study the crust and its history and (the "Holy Grail" of the
mission, so to speak) see if we can deduce something about the
solid/liquid composition of the moon's core.
This data will be thousands of times better than the previous Apollo
data, especially on the back side where Apollo had no direct tracking.
Using a lot of cleverness, the mission spends a few months (instead of
3-1/2 days) to reach the moon, for a little less energy than the direct
Apollo approach. It's supposed to arrive around New Year's Day of 2012
(the first craft on 12/31/11 and the second on 1/1/12) and do it's
science in three one-month global mapping sessions.
This knowledge will also improve future navigation of the moon (like by
astronauts) from the kilometer level to a few meters, important if you
want to land on, not merely "near" the landing pad.
Meanwhile, other people continue to work on explorations such as the Mars Exploration
Rovers that are in the seventh year of a planned 90 day mission at
two sites on Mars looking for signs of water or life, ancient or even
modern. Anything that blocks the sun to these solar-powered robots
could yet be their Achilles Heel.
Mars
Science Lab and Volkswagon Beetle sized nuclear powered Mars rover
has been delayed two years, causing consternation at JPL and all the
way to the highest levels of government.
The Cassini spacecraft
arrived at Saturn 2004 June 30 with a perfect orbit insertion burn. My
favorite is the navigation page with simulated
views where you can see what Cassini sees and its current location
in the Saturn System.
I continue to follow with interests the exploits of the Space Frontier Foundation
inspired space upstarts such as Space
X, led by Elon Musk of PayPal fame. They finally got something all
the way into orbit on their fourth try last year. Last fall I visited
their Hawthorne facility as a potential customer for Dragonlab.
There's also Scaled Composites
that won the Ansari X-Prize
in 2004 by flying the mass of three humans (including one real human)
to over 100 km altitude in the same vehicle twice in two weeks. There
was an accident at the plant in summer 2007 that has slowed them down
some, but they are still working with Sir Richard Branson of Virgin Galactic (also Virgin
Atlantic) to take half a dozen paying customers ($200,000 a seat)
over 100 kilometers into near-space for a few minutes of weightlessness
and sightseeing.
Elon, commenting
on Burt, says that the SpaceShipOne / SpaceShipTwo type suborbital
adventures only get 1.5% of the way to earth orbit, where any action
really starts, earth orbit being half way to anywhere in the universe,
by energy. My own calculation says 3% (just 2gh / v^2 for 100 km
suborbital height and 8 km / second orbital speed) but who's
quibbling?
There is a (relatively friendly) tension between the government and
private enterprise about all this. There is a perception that space
flight is so complicated and expensive that only governments can do it and everyone has grown so
used to this that the real perception is that only governments are allowed to do space flight.
Without real competition, places like NASA end up thinking things like
"Safety is Job One" is somehow a priority in the space exploration
endeavor, incongruous as that sounds on the face of it. Sure, safety
is important, but if we want to guarantee absolute safety of everybody
everywhere, we wouldn't be fooling around with rockets and high
explosives at all.
Private enterprise, after many false starts and missed promises is
finally getting off the ground, however. Their problem is that they
need a payingmarket of
some sort. True enough, NASA can ligthen up and just pay for things
rather than doing them, as one example of how to "privatize", but
that's still government money. After the big communications
constellation bust last decade (Iridium, Globalstar, etc.)
they (folks like the Space
Frontier Foundation) are now thinking that space tourism is where
the money might be. True enough, several people have shelled out $20
million to fly to space stations as private citizens, and there is a
larger market for cheaper tickets. Would you pay $190K for a three
minute sub-orbital flight after three days of training? Would you be
surprised to learn that that's about what participation in an
expedition to Mt. Everest costs?
We call this private enterprise versus government thing "furry mammals
scurrying around the feet of dinosaurs." Now we're in an economic ice
age. Who knows what will happen?
The tension is best summed up in the flight day quip, "SpaceShipOne,
GovernmentZero" which, though a bit of a low blow, is indeed accurate.
My own feeling is that I want somebodyto explore space and get a real start
moving people off the planet. Working as a builder and navigator of
solar system robots at JPL, I still see plenty of personal action and
contribute toward that goal.
GPS/MET
Instrument Configuration - Here I designed a method for a GPS
equipped satellite to schedule and perform its own atmospheric
soundings of the GPS signals without ground intervention.
A story
about software development at Microlink, Webster, Texas (now
defunct).
This is my "Silver Snoopy". Members of the STS-99SRTM team (see "Resume"
above) were awarded these for ... well, for pulling it off. Except for
this radar, JPL usually has little to do with the Space Shuttle or
manned space flight. Shuttles occasionally land in California,
however. One day when I didn't realize this was happening there was a
double knock at the door. I got up and answered to find no one there.
Shuttle sonic boom on final into Edwards....
The flowers are a dozen yellow roses that Viannah,
on the occasion of her first paycheck from Von's grocery (a summer job)
gave Viann, her mother, (2004 June 26).
A "Silver Snoopy" is a high award at NASA, comparable to but even
cooler than theNASA
Exceptional Service Medal, “for leading the Shuttle Radar
Topography Mission Global Positioning System design, development, test,
and delivery task.” May
7, 2001(the citation on
mine), that some of us got for the same job. The "Silver Snoopy" was
commissioned from Charles
Schultz, creator of Peanuts,
by the astronaut corps, is in limited supply, and must be presented in
person by an astronaut. Mine was presented by John M.
Grunsfeld who did not fly on SRTM. Rather, he happened to be the
next astronaut to make a state visit to JPL after these particular
awards were approved. Grunsfeld is famous as (maybe) the last
astronaut to repair the Hubble Space
Telescope (STS-109).
That's
Snoopy sitting by his box, the only time he's ever been out. (They
warned us not to put these on e-bay, so don't ask.)
Here I am
trying to put him back in his box.
A few thoughts on the notion that
people might go to Mars affordably by planning not to come back. An analog of travel to Mars with the discovery of
America was that the very first explorers and surveyors did go planning
to come back and typically did, with some pain. But it wasn't long
before there were settlers, typically middle class folks, who cashed
out their lives and moved to the new world expecting never to return.
A couple of centuries after that, there were people who were coming to
America planning to make their fortune and return home. As they got
old, living crop to crop, they began to realize that they would not be
going home. This is the origin of the "Prairie Home Cemetery," the
place where first generation "settlers" are buried. Of course, their
children always thought they lived here. This is the "Prairie Home" in
"Prairie Home Companion."
In spring 2009 I visited Space-X in Hawthorne, CA, representing small
payloads for upcoming launch opportunities and asked a question of Elon
Musk that got an answer that agrees with Buzz Aldrin on this topic.
Apparently there is discussion of one way planetary trips in the
futurist community.
Elon stated that the goal of Space-X is to "enable a spacefaring
civilization." So, after a bunch of questions relevant to biology
experiments, I said (showing my JPL colors...), "When you talk about
'spacefaring civilization' I think of leaving the earth. What is your
long term plan in this respect?"
He quipped the real answer first, "One step at a time..." which was met
with general laughter. But he does have a plan in this form: "If you
look way, way out, when the price of a one way trip (my emphasis) to Mars
is about the cost of your house, say $2,000,000 (we presume that Elon
owns a slightly nicer house than we), there are people who would move
there. It's not for everybody, indeed, it's not for most people, but
there will be enough people [like the Mayflower folks] who will cash
out and move to Mars permanently to make it a viable business."
Note that this is also a major theme in the Red Mars / Green Mars /
Blue Mars trilogy of Kim Stanley Robinson. The first trip is a round
trip, but quickly thereafter they start sending people with the intent
of enabling colonization, then colonizing. (Late in the trilogy, a
crises on earth allows Mars to declare independence and become their
own nation-planet?. Robinson gets huge leeway to discuss any set of
topics he wants through this device -- politics, soil science,
astrodynamics, geriatrics, you name it.) You get to phases where there
are always trips in progress in both directions, kind of like the
trans-Atlantic traffic of the 18th and 19th centuries. ... and
today.
This is something of a paradigm shift from Martian Chronicles.
I think the big holdup right now is the perceived resource situation.
The people on the Mayflower were expecting grass and trees and small
animals and water and air and other things that they were used to
consuming to be there for the taking when they arrived. There is not a
big resource draw to Mars or someplace like that yet. If there were,
Exxon would already be there, as we say. Ironically, the resources
expected by the Mayflower people failed them. Most of them died the
first winter, partly due to poor planning, but largely due to bad luck
with the weather. The first settlers on Mars might do better. Who
knows?
Buzz is advocating for "Aldrin Cyclers," a technique developed by him
and Dennis Byrnes (JPL) to basically put up a lodge/depot in the
trans-other-planet-and-back cyclic orbit, then you just fly up to it
and back when it happens by.
Developing that infrastructure from our current status and mindset is
itself mindboggling, and, how many cycles would it take to actually get
something major established that could be used by people? Cycles are
long. Years!
Aero-capture is the money saving arrival technique of the future - and,
in our current mindset and status, always will be. Hey, we did
aerocapture on Mars Climate Orbiter -- by mistake. Sorry.
-- There is no such thing as "boldly go" in our business right now.
But, most unrealistic is yet anther call for a decades-long focussed
goal. Clearly what we need - everybody calls for it all the time -
nobody does anything about it. Every new administration in Washington
starts out by "studying the problem" from a clean sheet of paper, then
trying to steer in some random new direction. This happens every 4 or
8 years. The inability to have a "decades long" goal is built into the
very Constitution. So, Aldrin perfectly predicts the guaranteed future
in his alternative clause:
"On the other hand, if we wander aimlessly, pick our way from one
short-term goal to another, lose vision, ambition or commitment, we
will find ourselves spending the next fifty years the way we have spent
the last -- without significant outward movement. "
This is exactly what we will do -- atbest.
A few thoughts on the man-made object
that will last the longest 7/16/12
First, we can simplify things (losing a little generality) by saying
that anything in earth or heliocentric orbit will be wiped out in the
solar nova. The sun will expand and stay expanded for millions of
years. Earth will either be swallowed up or burned to a crisp which
will then disintegrate. Everything in earth orbit will be lost in the
mess. Anything in solar orbit that was launched from the earth is
either at about the same distance as earth and will suffer the same
fate, or is in an elliptical orbit at least part of which will come
down to earth distance (or up), ditto.
I guess there's stuff sitting on Mars. We could get really technical
here. I don't know how big the nova will get or what it will eat up.
Maybe earth, maybe Mars, maybe neither, maybe both. So, maybe
something on Mars will be the last survivor, but I think erosion from
sitting on a planet with howling dust storms will pulverize anything
there in a few short eons.
There are five NASA missions escaping from the solar system: Pioneers
10 and 11, Voyagers 1 and 2, and New Horizons, on the way to but not
yet at Pluto. They, too, will be sandblasted by the occasional
particle over the coming millennia. (The space they are in is the
hardest known vacuum - less than an atom per CC and dust particles,
made of billions of atoms, are much much less common.) I don't think
they'll be ground to powder faster than things sitting on Mars, not by
a long shot but they eventually will. Will it take millions or
billions of years to make them unrecognizable as intelligence-built
technology? Don't know. I've seen pictures of Voyager passing it's
first nearby star in several tens of thousands of years. The artist
showed some noticeable damage.
Of course, there's some small chance they'll splat into something big
and, basically, become ore thereof.
One of the Star Trek movies, the one directed by Shatner, opens with a
sequence where Klingons are blowing up Voyager 2 as target practice --
space debris. I remember the day Shatner and his entourage came to JPL
to do that shoot. I remember thinking when I saw the movie that would
never happen. In 2400, Voyager 2 will only be like 1500 AU from earth
(see AU discussed below) and that's nothing - barely a light week from
the earth, not even a light year, much less half way across the galaxy
near Klinganor. If Klingons are right in our back yard doing target
practice, we need to be wondering about it! It's like Russian military
exercises on Catalina! (Yes, the Russians are supposed to be friends
these days. So are the Klingons.)
I think the real answer is that the object that is going to go furthest
and/or survive longest hasn't been built yet. Both Isaac Asimov and
Robert Forward, probably among many other SciFi writers, made (or
quoted, I don't know who they quoted) the claim that no one should
start an expedition to the stars anytime soon because in a generation
technology would allow travel ten times faster and so an expedition
that started 20-30 years from now would soon overtake the one that left
first making it irrelevant. This effect would continue up until you
could make an interstellar trip in only a few decades (i.e., a working
lifetime), be it driven by incremental or breakthrough advances in
technology. Of course, at the relativistic speeds that will require,
we will discover the problems with space not being near as empty as we
now imagine. It may be like trying to swim fast at the bottom of the
ocean, or worse.
Given that, I think that all five of the craft racing out of the solar
system now will eventually be recovered by hobbyists, the Bob Ballard's
of the year 3000 or whatever, and brought back to earth, or at least
into the inner solar system where they will once again be in danger of
the destruction of The Nova. In any case, it's of little use for our
civilization to leave an artifact out in the unknown unless we somehow
also survive ourselves.
So, I think to answer the specific questions, Voyager 1 is today's best
bet, but it will be eroded by interstellar dust eventually. I don't
have a good guess for how long that will take, but it could be a
billion or more years, which makes it an interesting question -- what
will be destroyed first, the sun or Voyager?
Intersteller density is the piece I don't know. I don't think anybody
does to good precision, though astronomers and cosmologists must have
to calibrate for it (maybe that's the plethora of "dark matter"
everybody moans about). (No, probably not, it can't be that
simple.)
No chance of anything falling into the galactic core. The hardest
place to go in the solar system is the sun. To escape the solar system
(from earth) you need 12 km/sec. To go to the sun you need 30 km/sec,
(which by half M V squared is six times as much energy -- non trivial)
and you have to be a damn good shot, while staring straight into the
sun with sweat all over your eyes and everything. To go into the
galactic core would be similar but nearly infinitely harder.
But we saw on Nova the other night that one current theory is that our
whole four dimensional existence is just a hologram projected from the
surface of a black hole into which the universe has fallen. Not the
one at the center of the galaxy but one that is somehow central to the
whole universe. So in that sense, Voyager, and we, are already there.
And time doesn't matter.
Physicists!
A few thoughts on the most distant
transmitter 2012 July 4
I was recently in a workshop where "low frequency" radio astronomers
were talking about one of their "Holy Grails," is detection of the 1420
MHz Hydrogen line (21 cm) during the "Dark Ages" that is, the period of
time before anything in the universe made light. That's some 14
billion years ago plus and the hydrogen seen in such an observation
would be 14 billion years old and 14 billion light years away.
It's interesting because, from those Dark Ages, 1420 is red shifted
into our FM band, around 100 MHz, making it really hard to observe from
earth; too much rock-n-roll. What they need is a "low frequency"
(radio astronomers these days call 100 MHz "low", though it is formally
"very high") array on the back side of the moon. Not a cheap
endeavor.
A light year is 9460 billion kilometers -- 63,500 AU.
An AU (Astronomical Unit) is 149 million km -- 93 million miles, nearly
500 light seconds. I prefer to discuss things in the solar system in
AUs because you can draw a picture and show the earth and sun (specs on
any reasonable drawing scale) and kind of know the sizes. Things in
the solar system are easily conceived in distances of AU and times of
years. The earth, for example, travels around the sun at 6.28 AU/year
(the reason should be obvious). This works out to about 30 km/sec
which is why things in space have to go so fast by human standards.
So, with the meter sticks all worked out (and noting that space is
really big whether we're just in the solar system, or the whole
universe) here is the answer.
Distance from the sun: Earth, 1 AU; Jupiter, about 5 AU; Pluto,
between 30 and 50 AU, currently climbing out of perihelion (1999)
approaching 40 AU.
Currently the man-made DX distance record is Voyager I which is now at
120 AU, having passed Pioneer 10 at 70 AU in 1998 (which, in any case,
was lost in the noise (even to the DSN with a 30K system temperature on
a 70 m. dish!) at 80 AU in 2003). Voyager I is also the fastest
receding man-made object, at 3.65 AU per year. They think the
Plutonium will hold up into the mid or late 2020s, so it could still be
talking fifteen years from now at 175 AU.
I don't know this firsthand, but I think the limitation is that the
Plutonium based power declines to the point where the amount of power
into the transmitter doesn't overcome the background microwave noise
anymore. (It could, on the other hand, be that it won't produce enough
power to run the spacecraft at all.) Note that uplinking is not a
problem. We can build big dishes and virtually arbitrary power
transmitters (a MW is not unheard of) on earth, while Voyager is
limited to 2 m. dish and ~30 W.
120 AU is over 16 light hours meaning that if you send Voyager I a
command first thing Monday morning, it arrives at the spacecraft after
midnight and the response gets back to you around quitting time
Tuesday. That is if you keep banker's (i.e., not astronomer's)
hours.
Yes, it is three or four times farther out than Pluto, albeit in a
different direction.
So, my back of the envelope path loss for 120 AU (18 billion km, 11
billion miles) at 8 GHz is 315 dB unless I'm making a mistake
somewhere. By contrast we are accustomed to 154 dB path loss on our 10
GHz 100 km links. Of course a direct radio to radio link is much
easier than a reflection. (The 1296 EME path loss is comparable to the
whole Voyager I path loss!) When there are people on the moon with
radios (or just repeaters) they will be very workable down into the
general ham population. You won't have to be a San Bernanrdino Microwave
Society type!
