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Author: Marianne
Marianne Dyson is an award-winning children's author, science fiction writer, and former NASA flight controller. To invite her to speak or order her books, visit her website, www.MarianneDyson.com.
The
Moon’s gravity is lumpy. Areas where mass is concentrated have stronger
gravity such as where impacts have compressed the ground. These mass
concentrations, called mascons, pull spacecraft forward, back, left, right, and
down—making most low lunar orbits unstable.
NASA launched the Gravity Recovery and Interior Laboratory (GRAIL) mission in 2011 to map the location and strength of mascons. GRAIL consisted of twin satellites named Ebb and Flow that were placed in a low lunar orbit of only 34 miles. The distance between the two satellites varied slightly as they flew over areas of greater or lesser gravity caused by masses hidden under mountains and craters.
Large mascons were found underneath all the biggest impact craters on both the near and far sides. (Unlike the Sea of Rains and Serenity (the “eyes” of the Moon), the Sea of Tranquility where Apollo 11 landed didn’t form by impact, has no ring around it, and GRAIL showed no mascon under it. )
This map based on GRAIL data shows that the Moon’s crust is up to 37 miles (60 km) thick (white) on the far side. Impacts compressed and thinned the crust under large impact craters (blue and purple). The Sea of Rains, Serenity, and Crises form a row of low spots across the northern near side (left image). The crust is so thin at the Sea of Crises and the Moscow Sea (upper far side-right image) that olivine (purple stars), a mineral from the Moon’s mantle mapped by Kaguya is exposed on the surface. Credit: NASA/JPL-Caltech/IPGP
Because of mascons, the
Lunar Prospector spacecraft (1998-99) had to do a maneuver every two months to
stay in a 60-mile (100 km) polar orbit, and once a month to stay at 20 miles
(30 km) above the surface. Luckily future missions have some better long-term “parking”
options.
Frozen
Orbits
Apollo 16 released two subsatellites into
lunar orbits. PFS-1 stayed in orbit for one and a half years. PFS-2 crashed
after 35 days. Scientists soon discovered that mascons lured PFS-2 to its early
demise. PFS-1 avoided the same fate because its orbit was inclined (at 28 versus
PFS-1 at 11 degrees) so that it spent less time passing over mascons. (Inclination
is the angle that the orbit plane makes with the equator.) Their different
fates led to the identification of four stable or “frozen” orbits with
inclinations of 27, 50, 76, and 86 degrees. These orbits require less fuel to
maintain.
A first base on the
Moon will likely be placed near the south lunar pole because of deep ice
deposits (for fuel and life support) as well as tall mountains that offer
almost continuous sunlight (for power). Therefore, the 86-degree frozen orbit offers
a reasonable parking spot for return vehicles. The disadvantage of parking
there is that launch windows from those orbits to Earth occur only about every
two weeks.
Moon Direct
Instead of parking
near the Moon, Earth return vehicles can remain in Earth orbits. This Moon Direct
plan is explained by Robert Zubrin in
his book, The Case for Space. Astronauts would ride commercial rockets
to Earth orbit and catch their shuttle (called a Lunar Excursion Vehicle, LEV) from
there to the Moon. LEV then fly directly to the surface of the Moon with no
rendezvous in lunar orbit on the way out or back. The LEV can be resupplied
with fuel in Earth orbit (using lunar water) and support multiple roundtrips.
NASA’s Lunar Gateway space station is not planned to be in lunar orbit at all. Instead, it is slated for an ellipse around a place in space called Lagrange Point 2 (L2, above the far side) and never come any closer to the surface than about a lunar diameter. Zubrin and NASA’s former Administrator and others consider this an unfortunate choice. From the surface of the Moon, it actually takes more fuel to reach L2 than it does to reach Earth orbit. It also requires fuel to “park” anything there and can only be accessed once a week. Some have suggested that the Gateway move instead to an Earth-Moon cycling obit (to the Moon and back on a regular schedule) and serve as a fuel depot.
Lumpy lunar gravity requires some creative solutions for parking Earth return vehicles while working on the surface. The main purpose for a first lunar base, in my opinion, is to process lunar water into fuel. This lunar “gas station” will enable easier access to all other destinations in space, including Earth, any Gateway stations, and missions to Mars. A lunar gas station will also hopefully lead to affordable flights for those of us who want to experience lumpy gravity for ourselves!
I was a teenager at summer camp when Apollo 11 astronauts Neil Armstrong
and Buzz Aldrin landed on the Moon 50 years ago this month. Below is the story
of that day as recorded in my memoir.
Marianne and “Red” in 1969 at Rambling Acres. Photo courtesy Marianne Dyson
“Girls! Girls!” someone
hollered from outside the big red barn. I was at Rambling Acres
Horseback-Riding Camp, near Canton, Ohio. “Put your brooms away and come
up to the house! They’ve landed on the Moon!”
I didn’t need a second invitation.
I’d enthusiastically followed the space program since first grade when John
Glenn had orbited the Earth. I was 14 now, and I loved space even more than
horses. The previous spring, I’d even written and hand printed a 60-page book,
“The Apollo Program” for my eighth-grade English class.
I dashed from the stall, latching
the gate behind me, and ran up the dusty road to the camp owner’s house.
“Wait up!” my best friend Chrisse hollered as she scampered up the
road behind me, followed by the other girls.
The owner, Mrs. Noll, insisted we
brush dust and straw off each other’s clothes and remove our dirty shoes before
entering her house. Then we filed into her living room and settled down
cross-legged on the carpet, facing the television set. The TV was a stand-alone
piece of furniture, a box on legs about three feet tall with “rabbit
ears” antenna. The picture was in black and white.
The familiar face of CBS News anchor
Walter Cronkite appeared on the screen. In his deep voice, he explained that
Mission Control in Houston had given Apollo 11 astronauts Neil Armstrong and
Buzz Aldrin the “go” to exit their spacecraft. The men had been
scheduled to sleep but were too keyed up after the exciting first landing on
the Moon.
I was keyed up, too. It was the
first day of camp, and I’d just met five new girls. We had plenty to talk about
while we waited for the astronauts to leave the lunar lander. “Which one
do you think is the cutest?” Sue asked me as we loaded our plates for
dinner.
“It doesn’t matter,” I
said, snatching a roll. “They’re married!”
Sue frowned and then sighed as she
scooped beans onto her plate. “Wouldn’t it be dreamy to marry an
astronaut?”
“Yeah,” I agreed. Then I
added silently, “But even better if you could be one!”
We finished dinner, and the
astronauts still hadn’t emerged from their ship. We wondered what they were
having for dinner. (I found out later, bacon cubes. Yuk!) We trotted back to
the barn for evening chores. I brushed the horse who shared my nickname, Red.
Then we got our showers and returned to Mrs. Noll’s house.
The television spurted static-filled
voices of the crew talking with Mission Control. What was taking so long? Why
didn’t they just open the door and hop out? Bedtime came and went. Luckily,
Mrs. Noll let us stay up for this historic occasion.
Finally, six hours after Apollo 11
landed, the ghostly black and white “live from the Moon” image
flickered on the screen. At 10:39 p.m. Eastern time, Armstrong spoke the
now-famous words, “That’s one small step for man, one giant leap for
mankind,” as he stepped backwards off the ladder onto the lunar surface. I
remember thinking how I’d like to follow in his footsteps.
But in 1969, there was no such thing
as a female astronaut. No woman in my family had even gone to college. Yet, the
previous winter, I’d written in my diary, “I wish very much to be able to
be an astronaut. I’m sorry I’m a girl, but I’ll have to try harder then.”
As I gazed up at the half-full Moon
that July night, I marveled that there were men up there looking back at me. If
those men could walk on the Moon, then maybe a skinny red-headed girl from a
small town in Ohio could find a way to go to college and one day work for NASA.
Just ten years after the Moon landing, I was hired by NASA to become one of
the first female flight controllers. In 1982, I had the privilege of working at
a console in the historic Mission Control room (during the fifth Space Shuttle flight)
that has now been restored to the way it looked in 1969.
While at summer camp, I could never have imagined that 50 years later, I’d
not only have worked in Mission Control alongside some of the “unsung heroes”
of Apollo and the first female astronauts, but I’d also coauthored two children’s
books with Buzz Aldrin and be releasing a new book, Welcome to the Moon,
commissioned by Buzz’s son, Andrew, to help inspire a new generation of lunar
explorers. (See below.)
One thing I also could not have imagined back then is that 50 years would
pass without a woman setting foot on the Moon. So as I gaze up at the Moon this
July and celebrate the historic achievement, I’ll be thinking about what more I
can do to help young people acquire that “can-do” Apollo spirit that will
motivate them to harvest the unlimited resources and exciting opportunities
space still has to offer.
Writing about Space
Apollo 11 lifted off at 9:32 EDT on July 16, 1969. The Eagle landed on July 20 and lifted off the Moon on July 21.
So, in honor of the 50th anniversary of the first trip to the Moon, at 9 am on July 16, the Amazon eBook of Welcome to the Moon (by Marianne Dyson and Lindsey Cousins with a foreword by Buzz Aldrin’s son Andrew), drops from $9.98 to 99 cents and stays that price until 5 PM on July 21 when they lifted off of the Moon. Autographed print copies can be ordered through Marianne’s website. All proceeds benefit STEM education via the Aldrin Family Foundation and ShareSpace Education.
July 25, 1:30-4 PM, event: Two Space Authors & an Astronaut. Join Marianne Dyson, Melanie Chrismer, and a surprise astronaut (sorry, not Buzz!) at Evelyn Meador Library, 2400 North Meyer Ave, Seabrook, TX 77596, 281-474-9142. I’ll use models and share excerpts from my books to show how Apollo went to the Moon and Back. Books may be offered for sale by the Friends of the Library. Free and open to the public. Sponsored by the Rotary Club of Seabrook.
Author Marianne Dyson’s May 2019 Science Snacks Newsletter
Hello, and a special welcome to new subscribers.
As we celebrate the 50th anniversary of Apollo, I thought I’d devote this Science Snack to some little-known lunar science performed by Soviet scientists in preparation for their own planned human landings on the Moon. The following is mostly an excerpt from my new book, Welcome to the Moon, which will be released June 17 from the Aldrin Family Foundation. (See book ordering information below.)
Buzz Aldrin tested soil hardness with this boot print. The length of the shadows reveal this print is less than an inch deep. (NASA/B. Aldrin)
One
of the first questions that scientists had to answer is How Hard is it? “It”
being the lunar surface! How
strong do the legs of a lunar lander need to be? Will the foot pads sink deep
into fluffy powder, break rocks into glasslike shards, or smack into solid
stone? To find out, Russian engineers devised an experiment for Luna 13 to test
the hardness of the lunar surface.
Like
its predecessors, at an altitude of 46 miles, Luna 13 inflated airbags and
fired its landing rockets. When it was 16 feet above the surface, the engines
shut down as a sensor contacted the ground (a method still employed by Soyuz
capsules). The landing capsule, in its airbag cocoon, was ejected and bounced several
times before coming to rest in the Ocean of Storms.
After bouncing to a stop, Luna 13’s
airbag deflated, and two booms sprang out from the body of the spacecraft. One
boom contained a small solid rocket, pointed down. The rocket shot a titanium cone penetrator (with a diameter of
1.4”) into the ground. A pin slid along a groove in the side of the casing to
measure how deep it went. The engineers had tested this penetrator on 14
different surfaces on Earth, including dust and concrete, and in a vacuum
chamber ahead of time. Depending on the surface material, the penetrator could
drill down two inches.
On Christmas Eve of 1966, the engineers
got the gift of data from the Moon. The penetrator dove in 1.7 inches. The team
concluded that the surface was volcanic rock (basalt) covered by a layer of powder.
Spacecraft cameras revealed rocks scattered on the surface. Of 181 counted, most were pebbles. Only three were larger than four inches and all less than eight inches in diameter. The experiment gave the engineers confidence they could safely land a cosmonaut on this surface.
To learn more about the historical and current science of the Moon in “layman’s” terms (written for gifted middle-school students), order your copy of Welcome to the Moon via my Book Orders page. (And Thank You!)
Writing about Space
To share what the first journey to the Moon was like, Buzz and I teamed up with pop-up artist Bruce Foster to create To the Moon and Back: my Apollo 11 Adventure. We hope you’ll share this historical American story with the whole family.
I’m pleased to
announce that my fact article, In Defense of the Planet, won the AnLab Readers’
poll! It is available FREE
on the Analog website.
Speaking about Space
I offer programs appropriate for school-aged children
up through senior citizens, as well as science workshops for students and
teachers. See my list of programs on the Author
Visits tab of my website.
Friday May 31, WriteFest
Weekend Festival, Anderson-Clarke Center (6100 S. Main St. Houston, 77005),
Rice University. The weekend festival includes panels, presentations, agent
pitch sessions, and a book fair. Look for me on panels at 2:45 and 4 pm.
See my website’s contact page for a
complete appearance schedule.
On Apollo 14, Alan Shepard famously hit the first golf ball on the Moon. Because of the stiff space suit, he had to hit one-handed. After several tries, he sent it off camera and claimed it went “Miles and miles and miles.” But did it really go that far?
Judging distance in space is tricky. Studies have shown that even on Earth, people routinely underestimate horizontal distances by ten percent. On the other hand, heights are usually overestimated by as much as 30 percent, especially when looking down or from a distance. (A pyramid appears steeper from a distance than it does up close.)
Credit: NASA AS14-67-9367.
Does the Apollo 14 lander seem closer than 650 feet (two football fields) or taller than 10’7”?The near horizon, sharp shadows, and a tendency to underestimate distance and overestimate height of objects makes judging distances difficult on the Moon.
A study conducted on space station astronauts shows these effects are exaggerated in space. Astronauts underestimated distances by as much as 35 percent, even for objects at close range. Astronauts with long arms perceived targets within reach that were out of range. They also perceived objects to be taller than on Earth. This effect may be in part because people use the height of their eyes above the ground to provide scale—and there is no floor when floating in space. [Reference: Distance and Size Perception in Astronauts during Long-Duration Spaceflight]
On the surface of the Moon, many of the cues used to judge distance, such as trees and trucks, are missing. The lack of air also makes objects appear sharper and thus closer—adding to the tendency to underestimate distance and size of objects. Finally, the Moon is a smaller world than Earth, so the horizon is much closer. From a height of about six feet, the horizon is about 1.5 miles away (compared to about 2.8 miles on Earth). Combining all these effects means that what first appears to be a small nearby rock is actually a distant boulder.
Astronauts also have difficulty predicting the motions of objects in space. During a space shuttle mission, catching balls moving at constant speeds was difficult. People are used to balls accelerating as they fall on Earth. So astronauts think they are moving faster than actual and reach for the balls too soon (and miss the catch!). [Reference: Does the brain model Newton’s laws?]
So did Shepard’s ball go miles and miles and miles? [Watch video.] The record for a golf drive (Mike Austin, 1974) on Earth is 515 yards/0.3 miles. Some people have speculated that because of the Moon’s low gravity and lack of air, a golf ball hit that hard might sail more than two miles. Considering Shepard was likely underestimating the distance by up to a third, I wouldn’t be surprised if the ball went a mile—but not more than 1.5 miles since it didn’t disappear over the horizon.
On a more serious note, distortions in perceived distance, height, and motions could have grave consequences during space missions. A poor sense of closing speed has been cited as a contributing factor in a collision with a docking port on the Mir space station in 1997. [Reference: Shuttle-Mir’s lessons for the ISS]
More studies on how people judge distances and react in space will help us better understand our ingrained biases when it comes to judging distances in space. Laser range finders and future AI lunar golf advisers may even help us figure out how much of a handicap to give an astronaut in a stiff space suit!
Writing about Space
I’m thrilled to announce my newest space book! Watch my website Book Orders page for Welcome to the Moon ordering information.
A Summer 2019 Release!
My fact article about a practice drill for what to do if an asteroid threatens Earth, In Defense of the Planet, is a finalist in the AnLab Readers’ poll. It is available FREE on the Analog website until the winners are announced at the Nebula Awards in May.
Speaking about Space
I offer programs appropriate for school-aged children up through senior citizens, as well as science workshops for students and teachers. See my list of programs on the Author Visits tab of my website.
Saturday, May 11, Comicpalooza, GRB convention center, Houston. I’m on two panels in the Literary Track (upstairs rooms). From 3-4 PM, Worldbuilding Tips and Tricks: How to Create Believable Worlds, and from 6-7 PM, Writing Historical Fantasy—Getting the Details Right!
Thursday, May 23, Bay Area Writers League, Clear Lake Park, Houston, 7 pm. “Beyond Self-Publishing: Becoming a Publisher. What are the financial, legal, personnel, quality, quantity, and time considerations of creating books for companies or individuals?
Friday May 31, WriteFest Weekend Festival, Anderson-Clarke Center (6100 S. Main St. Houston, 77005), Rice University. The weekend festival includes panels, presentations, agent pitch sessions, and a book fair. Look for me on panels and at the book fair. Register early for the best price ($95 to $185 one day only & $180-$375 F-Sun).
See my website’s contact page for a complete appearance schedule.
Considering that we are celebrating the 50th anniversary of Apollo, and that NASA hascontracted with Firefly Aerospace and Intuitive Machines to provide new lander vehicles, I thought you all might enjoy this article I wrote that was originally published in Ad Astra in 2013.
Every year at space conference parties, enthusiasts have pondered the question: If we flew an Apollo mission to the Moon with today’s technology, how would it be different? One enthusiast, five-time shuttle astronaut Jeff Hoffman, PhD, who is now a professor at MIT, assigned a couple of graduate students to find a definitive answer.
The students, Alex Buck and Austin Nicholas, presented their findings at the Brown University-Vernadsky Institute-MIT Microsymposium 54 held the Sunday before the annual Lunar and Planetary Science Conference in Houston in March 2013. Though Dr. Hoffman wasn’t able to attend (he answered questions via telecom), Apollo 15 Moonwalker Dave Scott was present to enthusiastically endorse their work and encourage the space community to act on it.
The study focused on using the basic Apollo architecture of a command and service module (CSM) to launch from and return to Earth, connected to a lunar module (LM) to go to and from the lunar surface with modifications made possible by current technology.
Technology upgrades to the lunar lander included higher efficiency propellants, lightweight materials for the structure, and state-of-the-art electronics for computing, avionics, and communications. The electronics provide “on the order of a billion-fold increase in terms of reduced power consumption and increased computing capability,” the students said. They also replaced the Apollo-era batteries with modern fuel cells that produce water as a useful byproduct.
The results were astounding. “We could cut up to 40 percent of the lunar module mass while still maintaining the same payload capability of the original lunar module.”
Landing Vehicle Comparison
Apollo LM
HALOs Lunar Lander
Payload Mass
500 kg
2300 kg
1200 kg
Sample Return Mass
100 kg
350 kg
700 kg
Crew to Surface
2
3
3
Surface Days
3
7
14
One problem with switching to cryogenic fuels for the Human Architecture for Lunar Operations (HALOs) lander is that the fuel tanks, which are between the descent engines and the crew cabin, are, like the space shuttle external tank, enormous. The students noted, “This makes surface operations very difficult because it puts the crew habitat and the ascent stage and payload really high above the surface.” So the young engineers asked, “What if you didn’t have to land on top of the descent stage?” Why not eject the descent stage a few kilometers above the surface and finish the landing with the ascent stage? They found the cost in propellant is minimal, and the two-ton descent stage provides the bonus of a fresh impact crater for study about 5 km (3 mi) from the HALOs lander.
Next, the students looked at landing constraints. “All of the Apollo landing sites were on the Nearside and in the equatorial region,” the students said. “If we want to get some increased return out of a future landing program, it wouldn’t really make sense to go back to all those same spots.” But, “to reach high-latitude sites near the pole requires a lot of plane change to come in from Earth and return to Earth,” they said.
An elliptical polar “parking” orbit for the CSM solves the problem. “Plane change maneuvers have a fuel cost proportional to the speed at which you’re going when you do the maneuver,” the students noted. Like comets speed up when close to the Sun and slow down farther away, “that speed is lower the farther away you are in your orbit. So making the orbit highly elliptical reduces the fuel cost of those maneuvers and thus the mass of the entire system.”
Because these elliptical orbits are so efficient, using them can save 30-50 percent of launch mass compared to not using them.
However, “We don’t have a single launch vehicle that can launch a monolithic Earth departure stage to take this much mass to the Moon,” the students said. “So you have to lift the system in several pieces and assemble them in Earth orbit.” They assumed one Delta 4 Heavy and two Falcon Heavies, and used a SpaceX Dragon capsule for the CSM. The different parts would then be assembled after an Earth orbit rendezvous (EOM), something that has become a routine part of space station operations.
The CSM and LM are attached to a Lunar Orbit Insertion and Descent (LOID) stage (that would be ejected just before landing). The LOID puts the CSM into an elliptical lunar orbit about one by 10 lunar radii. “The CSM stays there while the LM goes to the Moon.”
The HALOs plan requires three launches to place the Earth Departure Stages (EDS), lunar orbit insertion and descent (LOID) stage, the lunar lander (LL), and crew and service module (CSM, SM) into orbit. (Image credit: MIT, 2013)
Unlike Apollo, all three crewmembers would land. How long they stay depends on how much luggage they bring, and how many souvenirs they take home. “If you want to do a seven-day surface mission, you can bring a payload with you to the surface of over 2,000 kg (4,400 lbs) and return 350 kg (770 lbs),” the students said. The total mission from launch to landing would last about two weeks.
“For a 14-day surface stay, you can bring just over 1,000 kg (2,200 lbs) to the surface and return 700 kg (1,500 lbs) back to Earth.” The increased sample return is based on the steady collection rate of 50 kg/day (110 lbs/day). The total mission duration would be about three weeks.
Luggage might include an Apollo rover at 210 kg (460 lbs) with an 8 km (5 mi) range, or a souped-up Constellation pressurized chariot at 1,000 kg (2,200 lbs) with a 100 km (62 mi) range. An Apollo lunar surface experiment package (ALSEP) would take up 166 kg (365 lbs).
After lunar surface operations, the LM rendezvous with the CSM for return to Earth. (As in Apollo, the LM is discarded after use, but the students said future studies could examine the possibility of reusing the LM by “parking it at a gravitational semi-stable point such as L2.) The CSM parachutes into the ocean like the Apollo capsules did.
“We think you can go back to the Moon with people without needing a super-heavy launch vehicle,” the students concluded. “We can do that while improving our payload capability and surface stay duration. And, we allowed the capability of putting humans and payload anywhere on the Moon.”
When asked where they’d personally like to go, the students answered with a smile, “Mars!”
For high school and up, give a positive vision of the future, a gift membership in the National Space Society. Read my article, “Chinese Planetary Exploration Plans” in the 2018-4 (current) issue of Ad Astra magazine.
For future astronauts and lunar pioneers, get a copy ofTo the Moon and Back: My Apollo 11 Adventure, a pop-up book coauthored with Buzz Aldrin with art by Bruce Foster, and 2017 Best STEM Book, Welcome to Mars: Making a Home on the Red Planet.
For middle school and up, consider a gift print or electronic subscription to Analog Science Fiction magazine. My science fact article, “In Defense of the Planet,” is in the Nov/Dec 2018 issue. Also consider a copy of my stories, most previously published in Analog, Fly Me to the Moon.
No spacecraft has ever landed on the lunar far side. The only human-made object on the far side currently is NASA’s Ranger 4 that crashed east of Korolev crater (about 15 degrees south of the equator) in April 1962. But that is about to change!
If all goes well this December, the Chinese Chang’E-4 (named after a mythological Moon goddess) will earn the title of first to the far side. This spacecraft is a lander/rover combination similar to the impressive 2013 Chinese lunar mission called Chang’E-3. Its Yutu (rabbit) rover successfully explored the Bay of Rainbows (Moon’s left “eyebrow”) and returned exciting new scientific data about the lunar surface and subsurface.
The far side of the Moon is never visible from Earth, making direct communications impossible. Therefore, to communicate with the spacecraft and rover on the surface, the Chinese deployed a relay satellite called Queqia (meaning “magpie bridge” from Chinese folklore) earlier this year. Since June, it has been in a 28-day orbit around the Earth-Moon L2 Lagrange point, which is about 37,000 miles (60,000 kilometers) beyond the Moon.
Chang’E-4’s landing area will be in Von Kármán Crater which is near the center of the far side and about 45 degrees south of the lunar equator. This crater lies on top what may be the most ancient preserved impact in the solar system, called the South Pole Aitkin (SPA) Basin. From orbit around the Moon, the SPA Basin appears as a large dark bruise that is more than 8 km (5 mi) deep and has a diameter of 2500 km (1550 mi) which is about a fourth of the Moon’s circumference. [Ref: NASA Lunar Reconnaissance Orbiter]
The rectangle shows the landing area selected for Chang’E-4, an area about 55 by 25 km (34 x 15 mi.) wide within Von Kármán crater on the lunar far side. Ba Jie is the small (about 3 km/1.8 mi) crater to the west of the landing zone. [Image credit: LROC WAC Global Mosaic, NASA/GSFC/Arizona State University, rectangle is plotted based on Wu W R, et al., 2017]The floor of Von Kármán crater was selected because it is relatively flat, with no more than about 197 feet (60 meters) of elevation change in topography. The rover will map the thickness of the regolith (lunar soil) in this area, which should help researchers to date the age of Von Kármán’s formation and anchor a geological timeline for much of the lunar far side.
Several countries, though not the United States, are actively involved in Chang’E-4. Germany is providing a lunar neutron and radiation dose detector for the lander, Sweden is contributing a neutral atom detector for the rover, and the Netherlands provided a low-frequency radio spectrometer for the Queqia relay satellite.
Dr. Jun Huang of the Planetary Sciences Institute, China University of Geosciences in Wuhan noted that one of the public education experiments on the lander will concern studying a tiny ecosystem including vegetables and worms. These items will be the first non-human living things (other than bacteria left behind on spacecraft) to reach the surface of the Moon.
But perhaps the most exciting thing about this first exploration of the lunar far side is that the Chinese have embarked on a well-planned step-by-step approach to building space capabilities that will directly lead to human space settlements. After Chang’E-4 comes Chang’E-5, an ambitious lunar sample return.
CR1 and CR2 show two possible locations for the Chinese Research Station near Shackleton crater at the lunar south pole. [Image credit: Chinese Academy of Sciences, General Office of Lunar and Deep Space Exploration, presented at Microsymposium 59, March 17, 2018 by Dr. Chun Lai Li.]After that, they will use robotic missions to further explore the lunar far side south polar region. Their 10-year plan, which they have followed very closely, has these missions launching in 2023 with humans arriving as soon as 2030. While NASA’s attention is focused on space stations in high lunar orbits, the Chinese may become not only the first to land a spacecraft on the far side, but humans, too.
Writing about Space
My article, “Chinese Planetary Exploration Plans” with more detail about the Chinese space program is in the 2018-4 (current) issue of Ad Astra magazine. To get your copy, join NSS!
To the Moon and Back: My Apollo 11 Adventure, a pop-up book coauthored with Buzz Aldrin with art by Bruce Foster, is available for now from Amazon. Get one for all the kids, big and small, in your family!
My science fact article, “In Defense of the Planet,” is in the Nov/Dec 2018 issue of Analog. Paper or eBook subscriptions available.
Recently NASA announced the first woman, Holly Ridings, to be selected as Chief of the Flight Director’s Office. Flight directors lead the team of flight controllers in Mission Control. The Chief Flight Director is their boss. To reach this position, a person must demonstrate a high level of integrity: like Randy Stone (1944-2013) who similarly rose up from flight controller to flight director to chief flight director (and eventually led Mission Operations). I’d like to share his story via an excerpt from my memoir.
BEGIN EXCERPT (omissions marked with three dots … )
Diane [Freeman] and I were on the Ascent, or Silver Team, for STS-1. Our Flight Director was Neil Hutchinson who expected only the best and no excuses. And well he should. If something were going to break, it’d most likely happen during the dynamic ascent phase.
About a week before launch, Mission Operations Director Gene Kranz called the Silver Team into the auditorium in Building 30. His speech wasn’t the “go team” speech that I’d expected. It was more of a warning and a blessing mixed into one. He reminded us that the space shuttle was the most complex vehicle ever designed by man. “Things break and fail,” he said bluntly. “But,” he added, “You won’t fail.” He said that each of us had been trained more thoroughly for this flight than any team in history. Our managers and the crew were counting on us to make the right calls at the right time. He said he trusted us and that we should in turn trust each other and trust our training. He left us with the sobering absolution that “If the mission fails, it won’t be because of something you did.”
We filed out of the auditorium quietly, each of us lost in thought. No one had ever flown such an unwieldy vehicle, an airplane with stubby little wings strapped to a giant tank with rockets bolted onto the sides. Did we really know what we were doing? Apparently, Mr. Kranz felt that we did, as much as anyone could in a test program. After all, if we knew everything about how this vehicle would fly, we wouldn’t need test flights. He’d expressed the ultimate confidence in us without any false pretenses. He’d sat in on all the long sims. He’d seen us wrestle with failures and find ways to work around them. He knew every one of us by name–had questioned us in briefings, in meetings, and seen us let off steam at social events. He trusted us to do everything humanly possible to prevent or mitigate the consequences of any failures.
Even though I was just a lowly Timeline 2, I felt an immense responsibility to justify Mr. Kranz’s confidence in me. This was no game or simulation. Two men I’d worked with for more than two years were going to eat steak and eggs for breakfast, suit up, and climb aboard the Space Shuttle Columbia. The procedures I’d written for transitioning the computers, for opening the payload bay doors, for what to do if the FES [Flash Evaporator System] or Freon loops, or the primary computers failed, were stowed onboard. My name was on the inside cover of those books. Though others had reviewed and approved them, I felt responsible for those procedures.
I was too keyed up to sleep the night before the launch, scheduled for 45 minutes after sunrise, Florida time, on Friday, April 10. …. I wore a patriotic white jacket and a blue and white striped shirt. I proudly put my STS-1 and my silver team pins on the lapel of my jacket. I headed out, briefcase and sack lunch in hand. …
Once at my console, I fished a small instamatic camera out of my briefcase. We weren’t supposed to have cameras, but I hoped no one would mind if I took a few snapshots in the back room. I popped the square flashbulb on top. I took a photo of the row of controllers, with Diane in front. I handed the camera to Diane to take one of me. Unknown to us in those days of film cameras, all these pictures blurred. Afraid a manager might yell at me, I put the camera away. …
Marianne Dyson during STS-1 launch abort, 1981
Like in football games where the clock is stopped for time-outs, the countdown clock stops at certain times in the prelaunch preparations while controllers check data. During the hold at T-2 hours and 4 minutes, Young and Crippen were strapped into their ejection seats. If anything happened during the launch or the latter part of entry (below about 100,000 feet), those seats would blow them out of the cockpit. This capability was only available during the first four test flights and was the reason the crew size was limited to two astronauts.
Even though the Launch Control Center at Kennedy was in charge until the vehicle cleared the launch tower, Houston Flight had to give a “go” for the launch to occur. Hutchinson wouldn’t give that go unless he got a go from each member of the Silver Team. The countdown proceeded until the T-20-minute hold. Everything was going great, and we all refreshed our coffee and made final trips to the restroom.
When I plugged my headset back in, I heard a heated discussion on the data processing system loop. As DPS Randy Stone (1944-2013) related in his oral history session, “When we came out of the T-minus-twenty-minute hold, we had four good primary computers, but the backup computer couldn’t see two of the flight control strings in the vehicle. Clearly it was unacceptable to fly your first flight when the two systems didn’t match,” he said. …
Stone said, “My back room was analyzing the data, and … they came to me on the loop and said, ‘There is nothing wrong with the backup. The problem is with the primary computer system. It’s not sending data.’”
I heard Stone call the Flight Director, “Flight, DPS.”
“Go, DPS,” Hutchinson said.
“We want to transition everything back to OPS-9.”
OPS-9 was the prelaunch mode for the computers. So they did this and Stone said, “The computers all looked good, and I’m thinking, ‘Man, if we come out of this hold and it works, am I go to fly?’ I’ve talked to my back room, and Gerry Knori and Jim Hill and Bill Lychwick all said, ‘We don’t understand it. We don’t want to fly today.’”
By now the countdown had progressed to T-9-minutes and was on hold for ten minutes. The weather was beautiful. The astronauts were strapped in and ready. Hundreds of thousands of people, including politicians and celebrities, were waiting and watching. And so was Mr. Kranz who’d reminded us all of the seriousness of our responsibilities. The decision rested heavily on Stone’s shoulders.
While he contemplated the computer issues, one of the fuel cells showed abnormal acid levels. The countdown was halted. The fuel cell was quickly determined to be okay, and the countdown was set to resume after the hold.
Stone said, “I made a decision with the help of the folks in the back room that it is not the right day to go fly. So I got on the flight loop. … I said, ‘Flight, I don’t care what happens when we come out of the T-minus-nine-minute hold. DPS is no go for launch.’ And man, you could have heard a pin drop in that room. I mean, it went from a lot of buzz to quiet.”
On the Flight loop, Hutchinson asked, “Are you sure you are no go for launch?”
Stone said, “Yes, sir. We do not understand what happened here. If it works this next time, I can’t guarantee it’s going to work through ascent, and I can’t guarantee it’s going to work when we bring these computers back alive to do entry. I am no go for launch.”
When we came out of the hold, the computers still didn’t match up. But even if they had, Stone had already made his decision, and so had Hutchinson. Would the managers support this decision to scrub the launch? It was an expensive choice. The eyes of the world were on us, and the launch had been slipped again and again. But a flight controller had trusted his training and made a difficult call, knowing that even worse consequences might have resulted if he hadn’t.
The team at KSC and in Houston worked for three hours unsuccessfully to trace the source of the computer problem. Finally, the Launch Director halted the countdown clock and declared a scrub at just before 10 a. m. Young and Crippen, who had been lying on their backs for six hours, were helped out of the cockpit.
Stone said, “My claim to fame is I was the guy that was no go for launch on STS-1 before we ever found out if it was okay or was going to work when we came out of the hold again. And truly, I believe that was a turning point in my decision-making process where I was confident enough to say no in an environment when everybody else wanted to say yes.”
After the flight, the Center Director Chris Kraft, Jr. pulled Stone aside and told him that he’d made the right call, scrubbing the launch. About three weeks later, Stone was selected to become a flight director. …
We soon learned that the problem with the computers was a timing error that caused them not to sync up with the backup machine. …. IBM fixed the flaw in the software after the first flight so it couldn’t happen again.
END EXCERPT
So please join me in congratulating Holly Ridings on her selection as Chief of the Flight Directors Office. She is an inspiration to all.
Writing about Space
To the Moon and Back: My Apollo 11 Adventure, a pop-up book from National Geographic that I coauthored with Buzz Aldrin, with art by Bruce Foster, is available for order now from Amazon. Look for it in stores everywhere on October 16.
My science fact article, “In Defense of the Planet,” is in the Nov/Dec 2018 issue of Analog. Get your subscription now!
October 27, Saturday, 10-2. Free & Open to the Public: NASA Johnson Space Center Open House. Look for copies of To the Moon and Back at the JSC Employees Exchange Store either at the tent by the Saturn V or in Building 3 cafeteria.
Visible in the evening starting this month, the two brightest stars of Orion are showing off their colors. But red Betelgeuse (Orion’s left shoulder, pronounced “beetle-juice”) and blue Rigel (Orion’s right foot, pronounced “rye-gel”) are destined to produce truly spectacular performances in the future.
Illustration of the constellation Orion from: AstroBob.areavoices.com
Big and Bright
People used to think that all stars are about the same size. Therefore, stars that appeared brighter must be closer like flashlights near versus farther away.
Then in 1905, astronomer Ejnar Hertzsprung used parallax (see July blog) to measure the distance to both bright and faint stars. Surprise! Some bright stars were the same distance as dim ones, and some much farther away. The reason? Some stars are brighter because they are physically bigger, like a floodlight versus a flashlight. This was proven correct in 1920 when astronomers measured the angular diameter of Betelgeuse using the (then) new 100-inch telescope on Mount Wilson. Betelgeuse is so large that if it replaced the sun, it would stretch out past the orbit of Jupiter. [Ref: European Southern Observatory.]
Betelgeuse is Cool
Betelgeuse is very obviously a different color than most stars. Human eyes see it as orangish red whereas Rigel looks blue. These colors aren’t just pretty, they reveal the temperature of the star.
Human eyes are good at judging heat output by color. Anyone who has ever roasted a marshmallow quickly discovers that a blue flame will burn it to a crisp whereas a warm yellow fire or a set of red embers will slowly brown it. Thankfully, we don’t have to hold marshmallows up to various stars to prove some are hotter than others. Scientists have quantified the colors by wavelengths so all we have to do is look at their spectra to tell precisely how hot stars are.
Human eyes only see a portion of a star’s total spectrum, aptly named the visible spectrum. The “coolest” end of the visible spectrum is red. The “hottest” is purple also called violet. (Physics students memorize the order: Red, Orange Yellow, Green, Blue, Indigo, Violet, as the name ROY G BIV.)
So just by looking at stars we can tell which ones are the coolest! Betelgeuse is a cool red. In the middle, temperature-wise, is our yellow sun. Blue Rigel is the hottest. (See Bad Astronomy for why we don’t see green stars.)
Stellar spectra (seen via prisms or spectrometers) allow astronomers to measure the temperatures of stars. The surface of Betelgeuse is about 5800 degrees F, about half as hot as the Sun at 10,000 degrees. Rigel would vaporize our marshmallows long before we got close to its 36,000-degree surface. [Ref: Griffith Observatory.]
Why is Betelgeuse so cool?
Red in the End
The temperature of a star depends mostly on its mass and age. Stars form by gravity pulling gas into a ball until it is hot enough to start nuclear reactions. The rate of those reactions, and thus how hot the star gets, depends on how much gas ends up in the ball. Blue Rigel is 20 times more massive than our yellow sun.
But what about Betelgeuse? It’s red, so does that mean it’s smaller than the Sun? Nope. There are two kinds of red stars: “adult” main sequence stars (which are the most common of all stars), and red giants in their final days. Betelgeuse has almost as much mass as Rigel. It is red because it is dying.
As stars use up their hydrogen fuel, the centers contract, and the outer layers expand out and cool. The stars become giant red puff balls regardless of what color they started out. In about 5 billion years, the Sun will become one of these red giants, expanding out past the orbit of Venus and toasting Earth’s marshmallow. It only took Betelgeuse about 10 million years to reach the giant, or in this case, supergiant, phase. Because of its huge mass, Rigel will become a red supergiant too, likely in the next few million years.
The red giant stage is a relatively short period of a star’s life, which is why there are so few visible in the sky. The red giant stage is followed by a final collapse of the center of the star as it runs out of fuel and can’t push back against gravity’s squeeze. For small and average stars, the collapse produces a white (hot) dwarf star about the size of Earth. Big stars like Betelgeuse and Rigel collapse violently, producing supernovas and leaving behind pulsars or black holes. Astronomers estimate that Betelgeuse’s supernova will outshine a full Moon when it happens: which could be tomorrow or a million years from now.
So while enjoying the colorful “preview” show of Orion this fall, have fun thinking about how this constellation will look when Betelgeuse “moons” the sky and Rigel blushes red!
Writing about Space
An excerpt of my memoir, A Passion for Space, describing my experiences as a flight controller during the first space shuttle launch, will be included in the FenCon 2018 Program Book this September. Attend to get your copy!
My next book, coauthored with Buzz Aldrin, To the Moon and Back: My Apollo 11 Adventure, a pop-up book from National Geographic with art by Bruce Foster, is available for preorder now from Amazon. Look for it in stores everywhere on October 16.
My science fact article, “In Defense of the Planet,” is in the Nov/Dec 2018 issue of Analog. Get your subscription now!
With no air in space, lungs empty like popped balloons. Blood boils, turning people into giant bruises. Eyes pop and eardrums burst. Yuck!
People must have air. We need it to breathe, and we need its pressure on us so air and liquids inside us don’t escape. We also need the right mix of gases to stay healthy and avoid fires in space.
Providing clean spacecraft air for a three-year round trip to Mars is quite a challenge, but one we are learning how to meet thanks to the experience gained on the International Space Station. To help others (especially you science fiction writers out there!) understand and appreciate that there is more to the life support system than worrying about the Klingons causing a hull breach, I’m sharing a slightly edited excerpt from my children’s book, Space Station Science (which you can order via Amazon or my website).
Bring Your Own Air
At the beginning of the space program, NASA filled spaceships with pure oxygen—the only gas people need to breathe. But during an Apollo 1 training session, the 100 percent oxygen atmosphere caused a fire to spread so fast that the three-man crew was killed in a matter of seconds. After that tragedy, NASA began mixing the oxygen with nitrogen during ground tests. Nitrogen slows fires, and people are used to breathing nitrogen and oxygen because natural air is four parts nitrogen to one part oxygen.
Station modules are launched with natural air inside. This air quickly grows stale and gradually escapes. It must be replaced. The nitrogen and oxygen for space station air are hauled to space from Earth. In order to fit in smaller tanks, these gases are chilled into liquids. The liquids are warmed to gas again before being released into the modules.
The Russians use a system called Elektron to turn wastewater into oxygen. Water is about 90 percent oxygen by weight. Electricity separates the water into hydrogen and oxygen. The oxygen goes into the cabin. Hydrogen is dangerous. A leak into the cabin could cause an explosion. Therefore the hydrogen is vented overboard.
Oxygen and nitrogen are stored in tanks in the Progress resupply ships or mounted outside the air lock. Tank valves open like little doors, “inflating” the station when the air pressure inside drops below a certain level.
When guests visit, more fresh air is needed. But astronauts can’t open a window to get it. When the space shuttle visited, hoses with air holes were snaked through the tunnels and hatches. The hoses transferred oxygen from the shuttle’s cabin to the station’s modules. Just before a shuttle departed, it “puffed up” the station with an extra shot of air.
The Russian Soyuz, a much smaller vehicle, does not carry extra air like the space shuttles did. When it brings visitors to the station, the Russians use portable solid fuel oxygen generators to provide the extra air needed. These generators were first developed for submarines and were used on the Mir space station. Like portable heaters, each generator sits in the aisle of a module. Cosmonauts insert a chemical candle that “smokes” oxygen for 5 to 20 minutes. These generators get very hot, and twice started fires on Mir. The crew were not hurt either time, but because of the risk, the generators are used only during visits and as a backup system on the station.
Keeping It Clean
Replacing oxygen and nitrogen is not enough. People breathe in oxygen but breathe out carbon dioxide. Carbon dioxide is poisonous. It can cause sickness and death even if there is enough oxygen in the air with it. On Earth, plants absorb it. In space, chemicals do the job.
Space suits use canisters of a chemical called lithium hydroxide to absorb carbon dioxide. The space shuttles also used these canisters. Like a litter box used by many cats, these canisters must be changed often. New ones must be stored and full ones thrown away. Enough canisters to supply the station between cargo supply visits would fill an entire module. So the station has a reusable air-scrubbing system. The Russian system is called Vozdukh, and the American one is called the Carbon Dioxide Removal Assembly (CDRA, pronounced see-drah).
With no up and down, hot air does not rise. So station fans constantly stir it. Dust and debris collect on fan screens and filters.
After filtering, the fans blow the station’s air across beds of a chemical called zeolite, which is often used in fertilizers. The carbon dioxide in the air sticks to the zeolite while the oxygen and nitrogen sail on through. When a zeolite bed gets “soaked” with carbon dioxide, the airflow to it is shut off. The bed is heated, releasing the carbon dioxide overboard. Once all the carbon dioxide is gone, the zeolite bed is cooled, the airflow is turned back on, and the cycle starts over again.
Note: maintaining the CDRA system has proven quite challenging for space station astronauts as described in Scott Kelly’s book, Endurance, which I highly recommend.
Water vapor from breathing, washing, and sweating also must be removed from the air. Otherwise, it fogs windows and allows mold to grow.
To remove water from the air, the station uses a system that works like a dehumidifier on Earth. Fans blow the humid air over chilled water pipes. The water condenses onto the pipes like it does on glasses of iced tea. In Earth dehumidifiers, these drops naturally slide down into a collector tray. In the free-fall environment of space, spinning is needed to force the water to flow into a collector. This water is not wasted. It is stored in a tank and recycled for drinking and oxygen production. [End edited excerpt of Space Station Science.]
What combination of systems will astronauts headed to Mars use to keep their air fresh and clean? Whatever systems are chosen, they must operate for the entire time that astronauts are away from Earth—about three years for a round trip to Mars.
Writing about Space
The Callahan Kids: Tales of Life on Mars is going out of print at the end of August. The stories are forever, but the company that sponsored the anthology which has two of my stories (“Martian Mice” and “Dropping the Martian Ball”) has gone out of business. The eBook book targeted at upper elementary and middle-school kids is now only 99 cents on Amazon. The print book is $9.99 on Amazon, but only $9.00 if you use my coupon code via CreateSpace. See my Book Orders page right-hand column for the code. You may also order a signed copy from me through my website.
An excerpt of my memoir, A Passion for Space, describing my experiences as a flight controller during the first space shuttle launch, will be included in the FenCon 2018 Program Book this September. Register to attend to get your copy!
My next book, coauthored with Buzz Aldrin, To the Moon and Back: My Apollo 11 Adventure, a pop-up book from National Geographic with art by Bruce Foster, is available for preorder now from Amazon. Look for it in stores everywhere on October 16.
At the end of July, Mars will be its brightest in 15 years because it will be only 35.8 million miles (57.6 million kilometers) away. Since no one has ever been to Mars, how do we know this distance so precisely?
Triangles! If the length of one side and two angles of a triangle are known, the length of the other sides can be calculated. Way back in 1673, Giovanni Cassini (1625-1712) used this knowledge of triangles to estimate the distance to Mars. This method is called parallax. [Ref: A Teacher’s Guide to the Universe: Background: Parallax.]
Half the distance (R in the diagram) between two locations on Earth is the known (opposite) side of the parallax triangle. One angle is 90 degrees. The other angle is found by observing the object from the two locations (Cassini in Paris and fellow astronomer Jean Richer in French Guiana in 1673). From the two locations (1 and 2 in the diagram), the object appears in a slightly different place in the sky (A and B in diagram) defined by the distant background stars. The difference in position reveals the angle (ɵ in the diagram). Plugging the known distance and measured angle into the tangent equation*, the answer for D is revealed.
The distance (D) to a planet or star can be found by observing it from two locations (1 & 2) whose separation (R) is known, and then determining the angle (ɵ) between the observed position in the sky using distant background stars (A and B). Credit: NASA.
*The tangent of ɵ equals the length of the opposite side (R) divided by the length of the adjacent side (D) which is the distance. Because the angle is very small, the tangent is approximately equal to the angle. So the equation simplifies to D (in parsecs) equals R (in Astronomical Units) divided by ɵ (in arc seconds).
The farther away an object is, the “taller” the triangle and the smaller the angle, making it difficult to measure very accurately. Thus parallax measurements to planets are easier when the planet is at opposition, on the same side of the sun as Earth. Mars opposition occurs every 26 months. But the orbit of Mars is an ellipse. So the closest to Earth Mars can get is when opposition is near periapsis—when Mars is closest to the sun. Opposition and periapsis coincide every 15 years, and 2018 is one of those years.
An Alternate History
The years when opposition and periapsis coincide are also the best years, in terms of fuel and time spent in transit, to send spacecraft to Mars. Back in 1990, I wrote a science fiction story about a group of astronauts preparing for a trip to Mars this year so that they would take the first steps on Mars before the 50th anniversary of Apollo 11’s landing on the Moon. I rediscovered this manuscript (it was not in digital form!) in my closet recently and am in the process of turning it into an alternate history novel.
So when I go out to view Mars later this month, I’ll be imagining my crew on their way there this summer. If they had followed the trajectory of InSight that launched on May 5, they’d be arriving on Mars on Monday, November 26. [Ref: Planetary Society.] But to reduce radiation exposure, they would likely have launched on May 18, “passed” InSight en route, and would be arriving on Mars on September 10, 2018. Would that day become a holiday on Mars?
Imagine if the current crew of six (which includes only one woman) up on the International Space Station were instead on their way to Mars. Would they be worried about the global Martian dust storm in progress right now? Would every kid in the country know everything there is to know about their planned landing area in Isidis Planitia? I can almost hear my young self proudly telling my mom that this part of Mars was named after the Egyptian goddess of heaven and fertility.
Mars in the Teapot
Though no humans are yet scheduled to travel to Mars, at least we have learned how to measure the distance and send spacecraft there. InSight is a pretty cool little spacecraft, too. It has a probe that is a self-hammering mechanism that will pound itself into the ground, up to 16 feet (5 meters). It relays data back via its tether to the lander. What might it find under the surface?
So later this month, look for Mars in the southeast evening sky near the Sagittarius “teapot.” Mars will be glowing orange below and to the left of the teapot with yellow Saturn above the top. Saturn was at opposition on June 27. How far is it to Saturn? If you have a good telescope, and a friend on the other side of the planet, you can figure it out yourself using triangles. Or you can just Google the answer!
Writing about Space
My guest editorial on Gender Parity is in the July/August issue of Analog. You can read it free online, but you might want to subscribe so you can read my fact article “In Defense of the Planet” in the upcoming Nov/Dec issue. I also did a Q&A with the magazine that should be posted later this month on the Astounding Analog Companion.
My next book, coauthored with Buzz Aldrin, To the Moon and Back: My Apollo 11 Adventure, a pop-up book from National Geographic, is available for preorder now from Amazon. Look for it in stores in October.
Speaking about Space
I offer programs for school-aged children up through senior citizens, as well as science workshops for students and teachers. Please consider me for Author Visits.
September 21-23, Science GOH at FenCon XV in Dallas. See their website for program details. Writer GOH is Larry Niven.
