The Occupy Mars Learning Adventure

Training Jr. Astronauts, Scientists & Engineers


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Building A Simulated Mission Control Center

Apollo Flight Controller 101: Every console explained

Your handy reference to each station in the Apollo Mission Control room.

Ars recently had the opportunity to spend some quality time touring the restored Apollo “Mission Control” room at the Johnson Space Center in Houston, Texas. We talked with Sy Liebergot, a retired NASA flight controller who took part in some of the most famous manned space flight missions of all time, including Apollo 11 and Apollo 13. The feature article “Going boldly: Behind the scenes at NASA’s hallowed Mission Control Center” goes in depth on what “Mission Control” did during Apollo and how it all worked, but there just wasn’t room to fit in detailed descriptions and diagrams of all of the different flight controller consoles—I’m no John Siracusa, after all!

But Ars readers love space, and there was so much extra information that I couldn’t sit on it. So this is a station-by-station tour of Historical Mission Operations Control Room 2, or “MOCR 2.” As mentioned in the feature, MOCR 2 was used for almost every Gemini and Apollo flight, and in the late 1990s was restored to its Apollo-era appearance. You can visit it if you’re in Houston, but you won’t get any closer than the glassed-in visitor gallery in the back, and that’s just not close enough. Strap yourselves in and prepare for an up-close look at the MOCR consoles, Ars style.

The layout

For most of Project Apollo, MOCR 2 had a fixed layout. Each station handled a specific, related group of functions; some watched over the spacecraft’s hardware, or its software, or its position in space, or over the crew itself. Here’s how things were laid out for most of Project Apollo:

MOCR 2's layout through most of Project Apollo.
Enlarge / MOCR 2’s layout through most of Project Apollo.
NASA/Aurich Lawson

Projection screens

An Eidophor projector.
An Eidophor projector.

MOCR 2 is dominated by five large rear-projection displays at the front, which are topped by nine smaller displays showing chronographic information. The large center display, called the “ten by twenty” by Sy Liebergot (it measures 10 feet tall and 20 feet wide) was primarily used to display the vehicle’s position and status during the current phase of the mission, using a complex system of physical slides overlaid on plots or columns of numbers. Housed at several positions within the projection space behind the screens were powerful quartz-lamp Eidophorvideo projectors, which bounced images off of mirrors and up onto the screen surfaces.

The side screens could be used to display the same channels as the individual console screens; Sy noted that during Apollo, the left-most screens might be set to display the vehicle command history and the current page of the flight plan; the right-most Eidophor was used to display television images, either from cameras used during the mission or from network TV channels when needed. The mainframe-generated, slide-overlaid images the Eidophors projected up onto the screens were quite crisp and clear.

Eidophor projections of the Apollo 11 lunar module descent stage trajectory during the first manned lunar landing. The Eidophor video projectors showed a very sharp image.
Enlarge / Eidophor projections of the Apollo 11 lunar module descent stage trajectory during the first manned lunar landing. The Eidophor video projectors showed a very sharp image.
Another view of the Eidophor-projected screens from 1968, this time showing typical MOCR lighting.
Enlarge / Another view of the Eidophor-projected screens from 1968, this time showing typical MOCR lighting.
Diagram showing the process for projecting the orbital plot on the main 10x20 screen.
Enlarge/ Diagram showing the process for projecting the orbital plot on the main 10×20 screen.

Row one – “The Trench”

The front row of controller positions is collectively referred to as “The Trench.” It is, as Sy puts it, the “lowest and darkest” of the rows of consoles, being the closest to the big screens at the front of the room. The positions there were concerned primarily with what the spacecraft was doing and where it was going.

BOOSTER

On the far left of the Trench is the BOOSTER console. It was manned by three people during launch, and each person had primary responsibility for one of the massive Saturn V rocket’s three stages. The BOOSTER controllers were of critical importance during the launch phase of each mission, monitoring the performance of each stage and ensuring that the complex launch vehicle functioned correctly throughout the approximately nine-minute ride to orbit, and then again during the trans-lunar injection phase, where the third stage reignited to send the Apollo spacecraft out of low Earth orbit and onto its trajectory to the Moon. After the maneuver was completed, the console was occupied by mission-specific scientific experiment personnel for the remainder of the flight.

BOOSTER console diagram, Apollo configuration.
Enlarge/ BOOSTER console diagram, Apollo configuration.
The left half of the BOOSTER console today.
Enlarge/ The left half of the BOOSTER console today.
The right section of BOOSTER today.
Enlarge/ The right section of BOOSTER today.

RETRO

To the right of BOOSTER is the retrofire officer console, or RETRO. Where BOOSTER was responsible primarily for getting the spacecraft away from earth, RETRO was responsible for getting the craft back. RETRO kept a list of abort options—lists of procedures detailing what to do when things went wrong—during the return phase of the mission, and also kept track of the Apollo Service Module’s main engine when it performed its burn to break free of lunar orbit and return to Earth.

RETRO console diagram, Apollo configuration.
Enlarge/ RETRO console diagram, Apollo configuration.
RETRO's console today.
Enlarge/ RETRO’s console today.

FDO

Second from right is the flight dynamics officer console, abbreviated as “FDO” and pronounced “fido.” FDO monitored the vehicle’s trajectory at all stages of the mission. FDO is notable in that during Apollo, it was the only station other than the flight director which could directly call for a mission abort during launch, using a dedicated set of toggle switches. This heavy responsibility stemmed from FDO’s role of watching over the vehicle’s path; deviations from the preplanned launch trajectory could signal potentially catastrophic problems and would require swift and immediate action to make sure the crew was kept alive.

FDO console diagram, Apollo configuration
Enlarge/ FDO console diagram, Apollo configuration

Even after launch, FDO’s role was extremely important, as the Apollo spacecraft’s trajectory was foremost on everyone’s mind during all phases of the mission. Going to the Moon wasn’t simply a matter of pointing the ship at the Moon’s current position in the sky and firing up the engines; trajectories were delicately calculated loops around the constantly shifting bodies in the heavens, and changing the vehicle’s path by mere fractions of a degree could mean the difference between a safe splashdown or a violent, crushing death during reentry.

Detail of the abort request and abort reset panels on the FDO console today.
Enlarge/ Detail of the abort request and abort reset panels on the FDO console today.

GUIDO

The guidance officer, pronounced “guide-oh,” watched over the Apollo Primary Guidance, Navigation, and Control Systems (“PGNCS,” pronounced “pings” by some torturous acronym bludgeoning) on both the Command Module and the Lunar Module, and also had responsibility for the Lunar Module’s backup Abort Guidance System (“AGS,” pronounced “aggs”). GUIDO kept tabs on things like the velocity and vector reporting done by the onboard systems, and ensured that where the spacecraft’s computers thought they were actually reflected reality.

During the landing phase of Apollo 11, a faulty checklist procedure resulted in the Lunar Module’s PGNCS computer becoming overwhelmed with instructions and unable to do all that was being asked of it. The LM’s master alarm sounded, and GUIDO Steve Bales and his back-room team had to decide whether or not to abort the landing. Within 30 seconds, they were able to determine the cause of the issue and that it was safe to proceed. This is yet another instance where a controller’s intimate familiarity with spacecraft systems allowed them to quickly find the root cause of a complex issue and save a mission from a premature end.

GUIDO console diagram, Apollo configuration
Enlarge/ GUIDO console diagram, Apollo configuration

Your handy reference to each station in the Apollo Mission Control room.

Row two

The successive rows of consoles are elevated by about two feet. Stepping up from the trench takes us to the second row, which contains the infamous SURGEON console.

SURGEON

The far left console of the second row was SURGEON, occupied by a medical doctor—a flight surgeon—who monitored the health of the crew. His console usually displayed electrocardiogram and electropneumogram data, showing the astronauts’ heart and breathing rates, as well as the output of other sensors attached on and around the astronauts’ bodies.

SURGEON console diagram, Apollo configuration
Enlarge / SURGEON console diagram, Apollo configuration

It’s a well-known bit of conventional wisdom that pilots—and hence astronauts—don’t like doctors. The reason most often given is that a pilot can come out of a doctor’s office in one of only two conditions: fine, or grounded. The enmity between the astronaut corps and the flight surgeons tasked with keeping them healthy and alive is quite well documented in popular culture; the craziness suffered by the Mercury astronauts in 1983’s The Right Stuff isn’t too far from reality, and the adversarial tone remained throughout Gemini and Apollo.

The tendency to hero-worship astronauts means that the folks manning the SURGEON console often got a bad public rap. It was head SURGEON (and later director of Life Sciences at JSC) Chuck Berry’s recommendation to ground Apollo 13 crew member Ken Mattingly because he might have been exposed to the measles. This led to Jack Swigert’s assignment to the mission very late in the training process, which greatly upset mission commander Jim Lovell. Flight surgeons, it seemed, were the causes of all sorts of problems for the crews.

Sy laughed when he recalled the Apollo-era SURGEON’s role during missions. “He would show up 20 minutes before a mission, and he knew where the camera was in that corner, and he’d just stand up and comb his hair.” He shook his head. “They were useless.” He went on to relate a story that during a Gemini simulation, then-Flight Director Chris Kraft had one of the simulator technicians play a prerecorded electrocardiogram tape of a person undergoing an actual heart attack into the SURGEON console, then while it was playing queried the SURGEON desk as to the crew’s health. “He said they were looking just fine!” snorted Sy.

CAPCOM

If the astronauts felt that SURGEON was the least useful station, then the next station over, CAPCOM, was the absolute opposite. CAPCOM, or “Capsule Communicator,” was the only flight controller allowed to talk directly to the spacecraft’s crew. This was done both from a resource management perspective, so that all transmissions to and from the spacecraft could be easily tracked for transcription, and also for crew safety, to make sure that the crew received explicit instructions from a single source. Only once in Gemini or Apollo did anyone other than CAPCOM address a crew, and that was during Gemini 4 when Chris Kraft, sitting at the flight director’s console, instructed space-walking astronaut Ed White to terminate his spacewalk and return to the capsule. Kraft’s violation of his own system of flight controller rules was due to White skirting at the edges of the mission’s safety and time constraints in order to exceed the amount of time Soviet cosmonaut Alexey Leonov had spent spacewalking three months earlier.

CAPCOM console diagram, Apollo configuration
Enlarge / CAPCOM console diagram, Apollo configuration

The CAPCOM console was always occupied by an astronaut, in no small part to ensure that the spacecraft’s crew always heard a friendly, well-known voice over the radio, Additionally, the astronauts brought with them a familiarity with the spacecraft’s layout and operation and that was very useful, and it helped to have an astronaut to be able to describe things in “astronaut terms” to the crews.

EECOM

To the right of CAPCOM was EECOM, the Electrical, Environmental, and Communications controller. The “communications” part was removed from EECOM’s purview after Apollo 10, leaving EECOM tasked with watching over the Command and Service Modules’ electrical and environmental systems. This was a very broad range of responsibility, and when the shuttle program rolled around, the EECOM desk was broken down again into two separate stations.

EECOM console diagram, Apollo configuration.
Enlarge / EECOM console diagram, Apollo configuration.

EECOM, of course, was Sy Liebergot’s primary console, from which he and the other EECOM operators monitored the generation and distribution of power on the spacecraft, as well as the critical life support systems—both the power-generating fuel cells and the living, breathing crew required oxygen to function, and EECOM tracked that.

The EECOM console today.
Enlarge / The EECOM console today.

GNC

One more station to the right was GNC, the Guidance, Navigation, and Control console. Where GUIDO managed the guidance computer and software of the spacecraft, GNC was responsible for the nuts and bolts hardware side of keeping Apollo pointed in the right direction. The GNC operator monitored the state of the reaction-control systems and the Service Module’s main engine, as well as the hardware components of the spacecraft’s guidance systems.

GNC console diagram, Apollo configuration.
Enlarge / GNC console diagram, Apollo configuration.
The GNC console today.
Enlarge / The GNC console today.

TELMU

TELMU, another tortured acronym standing for “Telemetry, Electrical, and EVA Mobility Unit,” was EECOM’s counterpart for the Lunar Module, watching over the LM’s life-support and power systems just as EECOM did for the Command Module. The LM had no fuel cells, due to its incredibly tight weight restrictions, and so TELMU had to track the state of the LM’s batteries during the landing phase of the mission. TELMU played a significant role in the implementation of the plan to use the Apollo 13 LM as a lifeboat, figuring out a way to solve a seemingly unsolvable chicken-and-egg problem of how to power up the LM during the mission’s outbound coasting phase (a story which is detailed in the excellent IEEE article Houston, We Have a Solution, recommended by Sy as the most complete and accurate technical retelling of the Apollo 13 incident).

TELMU console diagram, Apollo configuration.
Enlarge / TELMU console diagram, Apollo configuration.
The TELMU (background) and CONTROL (foreground) consoles as they are configured today.
Enlarge / The TELMU (background) and CONTROL (foreground) consoles as they are configured today.

CONTROL

Just as TELMU was the LM’s counterpart to EECOM, the CONTROL position was GNC’s LM counterpart. CONTROL handled the hardware portions of the LM’s guidance systems, including its landing radar, attitude thrusters, and ascent and descent rockets, while the LM’s software and computers were under the purview of GUIDO down in the trench. (The Lunar Module and the Command Module used essentially the same computer with similar software, so one station handling both vehicles made sense on the software side of things). CONTROL is the right-most console on the second row.

CONTROL console diagram, Apollo configuration
Enlarge / CONTROL console diagram, Apollo configuration
Another view of CONTROL (foreground) and TELMU (background) as they exist today.
Enlarge / Another view of CONTROL (foreground) and TELMU (background) as they exist today.

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Finding the Perfect Tent for a Simulated Mars Project on Earth

2 Meter Dome Tent: The North Face 2017

“If you are planning on spending long periods of time in the mountains, this is the dream base camp tent.  This 2-Meter Dome was my living room, bed room, kitchen, and art studio for two months in the Himalayas.  It was so cozy I almost didn’t want to leave.” – Cedar Wright, The North Face® Athlete, Rock Climber. The ultimate eight-person expedition base camp tent, the 2-Meter Dome is extremely durable and efficient in merciless environs such as the Himalayas and Antarctica. Setting the standard for unrivaled performance in major expeditions, this is the tent top mountaineers trust in critical conditions. Part of the Summit Series™ collection- the world’s finest alpine equipment.

FEATURES

Dome Tent Front View 1.jpeg

Built on decades of research, rigorous lab and field testing, and loads feedback from TNF athletes, The North Face 2-Meter Dome Tent stands alone as the quintessential mountaineering palace for surviving the world’s most extreme environments. Part of The North Face’s highly coveted Summit Series, this modern expedition tent features a classic hemispheric shape that descends directly from Buckminster Fuller’s original 1975 prototype. Modern materials, serious advances in storm-proofing, and powerful ventilation systems make the 2-Meter Dome the ideal base-camp shelter for surviving an Antarctic deep freeze, braving an arctic winter, or hunkering down during a relentless, weeklong Himalayan storm.

  • Athlete-tested Summit Series designation means that The North Face created this tent for demanding pursuits in challenging environments
  • Super strong, 210D nylon fly has a 1500mm PU coating to repel the harshest high-alpine weather
  • Ultra-durable floor built with super-burly nylon to withstand days and weeks of continuous use; a 10,000mm PU coating provides industry-leading protection against water
  • An impressive 125 square feet of floor space fits up to eight sleeping bags
  • Super strong, lightweight, 11mm Easton aluminum poles slide through sleeves and crisscross multiple times to form an ultra-strong lattice of support
  • Sleeve attachment points distribute pressure from wind and snow accumulation better than a clip design for maximum strength
  • Steep canopy walls and geodesic shape allow you maximum space, fend off voracious winds, and shed snow with ease
  • Chimney vent allows for safe cooking and helps prevent condensation from building up
  • Dual doors allow for cross-ventilation
  • DAC Featherlite NSL poles keep weight down without sacrificing strength or durability
  • Interior canopy hang loops provide a spot to hang a flashlight or electric lantern
  • Square-shaped gear loft sold separately
  • Fast-pitch-compatible (footprint sold separately)
  • The North Face Summit Series
  • Item #TNF2660

An Expedition Expert Tent

This tent stood up to the test on the Baltoro Glacier in Pakistan at 16,300ft this past summer. Phenomenal tent for base camp that is easy to assemble with a group of four plus folks, and resilient to all the elements. Great windows & double door protection (with fly), along with several pockets/sleeves for storing gear. Good floor that is very strong and withstands climbers’ abusive tred. Shape allows for easy snow shedding and size is perfect for hanging out. We fit eight plus folks and extra gear and communications in this tent comfortably. The tent had no issue with hot to cold, and ventilates very well with the 2 doors & 2 windows unzipped. This tent is not wanting in any way, and the designers have covered everything you need in this product.

  • Summit Series™ represents the world’s finest alpine equipment and apparel
  • 2-meter dome tent is the ultimate eight-person expedition base camp tent
  • Hemisphere shape demonstrates the original geodesic dome principle developed by Buckminster Fuller
  • Easton 7075-E9 aluminum poles
  • Pole configuration creates steep walls and maximum user space
  • Two exterior windows and a chimney vent
  • Interior canopy loops
  • Dual doors
  • Fly Fabric: heavy-duty nylon oxford, 1500 mm PU coating
  • Canopy Fabric: heavy-duty nylon oxford, 1500 mm PU coating
  • Floor Fabric: heavy-duty nylon taffeta, 10000 mm PU coating

PRODUCT SPECIFICATIONS

STYLE:

A557

USE:

Expedition

TRAIL WEIGHT:

47 lbs (21.31 kg)

TOTAL WEIGHT:

51 lbs (23.13 kg)

FLOOR AREA:

125 sqft (11.6 sqm)

PEAK HEIGHT:

83 in (211cm)

STUFFSACK SIZE:

32″ x 23″ (81.3 cm x 58.4 cm)

SLEEPING CAPACITY:

8

NUMBER OF DOORS:

3


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Students from around the world look to Mars

UAE looks to Mars for STEM inspiration

(CNN)On September 12, 1962, John F. Kennedy told the United States “we choose to go to the Moon.” What JFK and the American public didn’t know yet was that by investing in its space program, it was also choosing memory foam, precision GPS and the cardiac pump, food safety standards, invisible braces and the Dustbuster.

NASA has a rich history of spin-off technology; byproducts of its mission to explore the solar system. It’s among the space program’s most tangible legacies, demonstrating that ambitious ventures can reap diverse rewards to the benefit of all.
In the present day and half a world away, Dubai is no stranger to moonshot projects. Many are stipulated by ruler Sheikh Mohammed bin Rashid himself, and space has become just one frontier.

Dubai's space ambitions take flight

Dubai’s space ambitions take flight 07:14
The UAE Space Agency was formed as recently as 2014, and Dubai’s Mohammed bin Rashid Space Center was established in 2015. The center has already successfully launched two home-grown satellites, and the Emirates is targeting Mars with plans for a probe in 2020 — the Arab world’s first mission to another planet. More ambitious still, there are plans to develop a human settlement on Mars by 2117.
(In comparison, NASA’s Journey to Mars outline extends to sending humans into low Mars orbit in the “early 2030s.” Dutch private venture Mars One plans to put boots on the ground in 2032, while Elon Musk’s SpaceX is aiming to do the same in 2024.)
At the World Government Summit in February 2017, the UAE previewed its vision of what that colony might look like. In November, their VR presentation was made available on YouTube.
In September, Sheikh Mohammed and Sheikh Mohamed bin Zayed Al Nahyan, Crown Prince of Abu Dhabi, unveiled renders of Mars Science City, a $136 million simulation center planned for the desert outside Dubai.

A render of the Bjarke Ingels Group-deisgned Mars Science City, planned for Dubai.

Designed by “starchitect” Bjarke Ingels and covering 1.9 million square feet — the largest project of its kind — it will include biome laboratories simulating the surface of Mars, agriculture testing areas and a museum. Much of it will be built using 3D printers, including walls made of desert sand.
No timeline was given for Mars Science City, but speaking at the launch Sheikh Mohammed told the audience “the UAE seeks to establish international efforts to develop technologies that benefit humankind, and that establish the foundation of a better future for more generations to come.”

The 1.9m square feet Mars Science City is designed to test future built environments on the surface of Mars. The UAE plans to create a human colony on the planet by 2117.

The Emirates’ space program is aware it’s entering towards the back of the race, and its modus operandi appears to emphasize the benefits of the journey over the final destination. It’s all part of a plan to stimulate the nation’s science industries and boost its STEM (science, technology, engineering and math) credentials.
“Our primary target is having education and outreach,” says Sarah Amiri, UAE minister of state for advanced sciences and science lead at the Emirates Mars Mission. “It’s about building people, it’s not about building buildings… It’s creating people that are creative enough to stimulate your economy and to stimulate the growth of your entire nation.”
In other words, space is a means to an end.
Afshin Molavi is a senior fellow in foreign policy at John Hopkins University, and monitors trends shaping the Middle East. “We sometimes think that the only way a space program is successful is when you have men on the moon planting a flag, or in the case of Dubai maybe rockets that land on Mars,” he says. “But (a) space program is successful because of what it does on Earth.”
Whether the UAE’s investment manifests itself in an off-world colony, a new generation of homegrown scientists, or the next Dustbuster, Emirati lives could be the better for it.


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Who wants to study about Mars in the USA this summer?

Mr. Barboza California Association of Gifted Conference 

Bob and InMove 1.png

 Mr. Barboza’s session was delightful as well as inspiring.  The session wasn’t just a sit and get, it engaged the audience.  The session went beyond being informative; it was in fact was a proposal.  This proposal was a call to teach differently to implement the Common Core and Next Generation Science standards in a meaningful way.  To do this he called on teachers to partner with him to make students into authors, composers, artist, programmers, reporters, mathematicians, and scientists.

The approach to do this was multifaceted.  Having students write “STEM stories” relating to the theme of “Occupy Mars” was promoted.  A STEM story is any science or science fiction like narrative that is accompanied by a sound track and sound effects.  The goal is to engage students in writing by having them enhance their writing with sound.  This was demonstrated during the session by humanoid robot and a laser activated musical instrument that a member of the audience played.

If students are writing STEM stories, then they will need an authentic audience to give them purpose.  Mr. Barboza proposed three ways for students to do this.  These were Kid Talk Radio, the Occupy Mars Band and characters, and a humanoid robot.  Kid Talk Radio is a website that hosts student’s stories and reports in an audio format.  The Occupy Mars Band and character will perform student STEM stories, using their teacher narrating the story in character.  Students might also program the humanoid robot to tell their story including music, sound effects, and gestures.

 

Mr. Barboza also wants to get students involved in projects.  The theme for these projects this year is “NASA and NOAA needs your help.”  Students will take on the role of junior astronauts in solving these problems.  Students will be involved with an augmented reality show during this endeavor.  Designing experiments for cube satellites, assembling robots from 3d printed parts, and Mars habitats will be designed using dodecahedron geometry as well as other mathematics.

 

The session ended with Mr. Barboza offering the possibility of partnering with him.  Partnership would be based on proposals submitted by teachers.  Proposals that include taking advantage of the ideas mentioned above would be highly valued.  Proposals that went beyond the ideas above and involved learners in solid project-based-learning might even receive grant money.  More importantly, Mr. Barboza has 38 specialists in various STEM fields ready to help teachers succeed at the projects in their proposals. 

 

Jim Cottrell

Middle School Science Teacher.


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How do we weigh planets?

Students from around the world will be studying space science from a distance though the Barboza Space Center’s Fellowship Program.   http://www.BarbozaSpaceCenter.com.  This information was shared by NASA.
illustration of a planet on a scale

In real life, we can’t pick up a planet and put it on a scale. However, scientists do have ways to figure out how much a planet weighs. They can calculate how hard the planet pulls on other things. The heavier the planet, the stronger it tugs on nearby objects—like moons or visiting spacecraft. That tug is what we call gravitational pull.


What does gravity have to do with weight?

Earth’s gravitational pull is what keeps the Moon in orbit around our planet. Voyager 1 snapped this picture of Earth and the Moon from a distance of 7.25 million miles. Credit: NASA/JPL-Caltech

When you stand on a scale, what it’s actually doing is measuring how hard Earth’s gravity is pulling on you.

If you were to step onto a scale on another planet, it would say something different than it does here. That’s because the planets weigh different amounts, and therefore the force of gravity is different from planet to planet.

For example, if you weigh 100 pounds on Earth, you would weigh only 38 pounds on Mercury. That’s because Mercury weighs less than Earth, and therefore its gravity would pull less on your body. If, on the other hand, you were on heavy Jupiter, you would weigh a whopping 253 pounds!


How do scientists use gravitational pull as a scale?

In order to figure out how heavy a planet is, scientists need to know two things: how long it takes nearby objects to orbit the planet and how far away those objects are from the planet. For example, the closer a moon is to its planet, the stronger the planet will tug on it. The time it takes an object (whether it’s a moon or spacecraft) to orbit a planet depends both on its distance from the planet and how heavy the planet is.


Why do scientists usually talk about mass rather than weight?

An object’s weight is dependent on its mass and how strongly gravity pulls on it. The strength of gravity depends on how far away one object is from another. That’s why the same object weighs different amounts on different planets. It’s sometimes easier to compare planets using a measurement that isn’t quite so complicated. That’s why scientists and engineers often measure an object’s mass—how much matter the object contains—rather than its weight.

Mass stays the same regardless of location and gravity. You would have the same mass on Mars or Jupiter as you do here on Earth.

illustration of Earth and Mars with a stick figure person atop each one, showing that while a person's weight would differ on both planets, their mass would be the same

Your weight is different on other planets due to gravity. However, your mass is the same everywhere!

What is the mass of Earth?

We know that Earth has a mass of approximately 5,970,000,000,000,000,000,000,000 kilograms. That’s a really big number!


How do you write a shorter version of a very big number? Exponents!

The Earth’s mass is 5,970,000,000,000,000,000,000,000kilograms. That is a lot of mass! Here is a shorter way of writing that big number: 5.97 x 1024 kg. That little 24 is called an exponent. An exponent of a number is how many times to use that number as a multiplier. So, in other words:

5,970,000,000,000,000,000,000,000 is the same as…

5.97 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10

which can be shortened to…

5.97 x 1024

What is the mass of the other planets in our solar system?

The table below lists all the planets in our solar system in order from least massive to most massive. You can also find the mass of each planet in kilograms, and how the mass of each planet compares to that of Earth.


Planets (in order of least massive to most massive) Mass
(in kilograms)
Each planet’s mass relative to Earth
Mercury 0.330 x 1024 0.0553
Mars 0.642 x 1024 0.107
Venus 4.87 x 1024 0.815
Earth 5.97 x 1024 1
Uranus 86.8 x 1024 14.5
Neptune 102 x 1024 17.1
Saturn 568 x 1024 95.2
Jupiter 1,900 x 1024 318
article last updated November 21, 2017