After a six and a half month journey across space, NASA’s Mars 2020 spacecraft and the Perseverance Rover will arrive at Mars Thursday afternoon (Feb 18) and land at 3:55 p.m. ET. It will plunge into the Martian atmosphere, complete the complex and nail-biting landing sequence, and begin the exciting task of exploring Mars, including looking for signs of ancient microbial life.
Perseverance’s new home will be Jezero Crater, a large impact crater about 45 km wide just north of the Martian equator. Jezero once contained a lake, which scientists think is one of the most ideal places to find evidence of ancient microbial life. The rover will also collect and store rock and regolith samples, which will be returned to Earth in a future mission for further analysis.
The mission also includes the robotic helicopter Ingenuity, the first of its kind to fly on another world. It will provide a scouting service for Perseverance by surveying the area around the rover, and pave the way for future such aircraft that can fly in the thin atmosphere and low gravity of Mars.
Let’s take a few moments off the political wranglings of the day and enjoy this marvel of technology and human ingenuity and understand what its mission means for all of us.
This is a longish diary, so feel free to skip the middle portion, if you are not interested in the technical details.
The Landing
Perseverance will touch down on Mars on Thursday, Feb. 18, 2021, around 3:55 p.m. EST.
The 7-minute landing sequence is the riskiest part of the mission and the one most likely to result in failure. No other agency besides NASA has successfully landed Rovers and Landers on the Martian surface. Out of total of 20 landing missions, only 8 have succeeded, all by NASA. NASA had one failure; all 11 missions by the Russians and Europeans have resulted in failure.
During landing, the rover will plunge through the thin Martian atmosphere, heat shield first, at a speed of over 20,000 kmph. A parachute and powered descent will slow the rover down to about 1.2 kmph (0.75 meters per second). A large sky crane will then lower the rover on three nylon cords to land softly on its six wheels. The sky crane will then fly away and crash some distance away.
The probability of success is relatively high since this mission uses very similar rover and sky-crane landing technology used in the NASA Curiosity rover mission. Curiosity landed on Mars on August 6, 2012 and is still going strong, exploring Mars, slowly and methodically.
Perseverance carries a new guidance and control technique called "Terrain Relative Navigation" (TRN) to fine-tune steering in the final moments of landing based on real-time imaging of the terrain below. This system will allow for a landing accuracy within 40 m and avoid obstacles.
For the first time, the landing will be recorded using onboard cameras. The Mars 2020 Perseverance mission carries more cameras than any interplanetary mission in history, with 19 cameras on the rover itself and four on other parts of the spacecraft involved in entry, descent, and landing. Raw and processed images will be available on the mission’s website.
If all goes well, we will be able to experience in high-definition what it’s like to land on Mars – and hear the sounds of landing for the first time with an off-the-shelf microphone affixed to the side of the rover. Another microphone on SuperCam will help scientists understand the property of rocks the instrument is examining and can also listen to the wind.
Here is an artist’s conception of what the landing will look like -
Mission Objectives
Percy has four main science objectives, with an emphasis on astrobiology and the search for past microbial life on Mars:
- Looking for Habitability: Identify past environments capable of supporting microbial life.
- Seeking Biosignatures: Seek signs of possible past microbial life in those habitable environments, particularly in special rocks known to preserve signs of life over time.
- Caching Samples: Collect rock and regolith samples and store them on the Martian surface.
- Preparing for Humans: Test oxygen production from the Martian atmosphere.
Here is a video overview of the mission -
The Trip to Mars
The Mars 2020 spacecraft was launched on July 30, 2020. The figure below shows the trajectory of the spacecraft since then, which is a straight shot without any gravitational sling slots around other solar system bodies. Every 26 months, Earth, Mars and the Sun align for the most efficient, least energy-consuming path between Earth and Mars, similar to what is shown below.
The Landing Site
Perseverance will land in the North-West region of the Jezero crater, just north of the equator. See the map below for the landing site and the locations of other lander and rover missions.
Jezero Crater
Jezero (meaning lake) crater is located near the equator at latitude 18.38°N. It is about 49 km in diameter and was formed more than 3.5 billion years ago.
The landing and exploration site was chosen because of the possibility of finding signs of ancient life there. Based on analysis of the topology of the area and surface composition, scientists believe that the crater contained a lake 3.5 billion years ago. Two rivers channeled water into it and deposited sediments into fan-shaped deltas. The sediments have been observed to be rich in clays, which only form in the presence of water. On Earth, scientists have found such clays in the Mississippi river delta, where microbial life has been found embedded in the rock itself.
The next image shows Jezero crater and the landing area of Perseverance, shown as the inner white circle, which is about 7 km in diameter. The channel carved out by the ancient river and cutting through the northwest section of the crater wall is clearly visible in this image.
Zooming in, we can see the channel and the fan-shaped delta inside the Jezero crater. The color-enhanced image shows the delta, a small crater inside the delta named Belva and the areas known to be rich in clays shaded in green. If all goes well, Perseverance will begin its adventure just south-east of the delta and explore the area near the delta and to its west.
The next image shows a bird’s eye-view of the area created using actual images taken by Mars orbiters and route Percy is likely to take in the next two earth years. Percy will explore the southern and south-western part of the delta and then continue westwards climbing 610 meters up the crater rim. Along its journey, it will collect rock and regolith samples in special canisters and store them in a common location or two, for pickup by a future mission for return back to earth.
You can go back and look at the landing animation video again and watch the rover parachute in over the delta and land just south-east of it.
Here is a simulated flyover view of the Jezero Crater and the planned route of Perseverance’s exploratory journey over the next two years. The starting point in the video is farther east of the starting point shown above.
The Ingenuity Helicopter
NASA’s Mars Helicopter Ingenuity will be the first to demonstrate powered flight on another world. It is a technology demonstration and assessment experiment and is not critical to the primary mission. It will provide a scouting service for Perseverance by surveying the area around the rover, flying in the thin atmosphere and low gravity of Mars.
Ingenuity will drop down from the belly of the rover and then fly up to five times during its 30-day test campaign. If will fly 3–5 metres above ground for up to 90 second missions, traveling as far as 50 metres downrange and back.
The one-way signal travel time between Mars and Earth on Feb. 18, 2021 is 11 minutes, 22 seconds, so real-time remote piloting of the helicopter is out of question. Flight plans will uploaded by controllers at JPL; however, Ingenuity will use autonomous control to manage its flight.
Item |
Description |
Rotors |
Counter-rotating coaxial rotors about 120 cm in diameter, 2,400 rpm |
Instruments |
Hi-res downward-looking camera for navigation, landing, and science surveying of the terrain |
Comm. |
Used to communicate with the Perseverance rover
Radio link using low-power Zigbee communication protocol
250 kbit/s over distances of up to 1,000 m.
|
Navigation |
Solar tracker camera and visual inertial navigation system
The inconsistent Mars magnetic field precludes the use of a compass
|
Power |
Six Sony Li-ion batteries, solar panels |
Computer |
Qualcomm Snapdragon processor (ARM architecture, used in smart phones, drones, etc), probably not radiation hardened |
OS |
Linux |
Future Sample Return Mission
For more sophisticated analysis of Martian regolith, there is a plan to transport the samples collected by Perseverance, back to earth in a future mission.
Rather than pulverizing rock the way Curiosity’s drill does, Perseverance’s drill will cut intact rock cores that are about the size of a piece of chalk, place them in sample tubes and drop off the tubes at designated locations on Mars.
Perseverance carries 43 sample tubes, five of which are “witness tubes” which are pre-loaded with a variety of witness materials that can capture contaminants such as gases released from different materials on the rover, chemical remnants from the landing propulsion system and Earthly organic or inorganic material that may have arrived on Mars with the rover.
The design of the mission allows scientists to analyze samples across a wide area of the crater and select the best candidates for return to earth.
The plan as described in www.jpl.nasa.gov/… is as follows -
- An orbiter from ESA will arrive at Mars in 2027
- A NASA lander will arrive in 2028, carrying a NASA rocket (the Mars Ascent Vehicle) and ESA’s Sample Fetch Rover
- The fetch rover will gather the cached samples and carry them to the lander for transfer to the ascent vehicle; samples could also be delivered by Perseverance
- The ascent vehicle will then launch a special container holding the samples into Mars orbit.
- The orbiter will rendezvous with and capture the container
- The ESA orbiter will fly back to Earth and the NASA Earth Entry System will land the samples on Earth.
A more detailed animation of the samples return mission -
The Science Instruments
Percy carries a variety of instruments to support its science objectives.
- SHERLOC — Scanning Habitable Environments with Raman and Luminescence for Organics & Chemicals. Contains camera, spectrometers, and a laser to search for organics and minerals. SHERLOC flashes an ultraviolet laser over surface material. Measurement of resultant fluorescence and Raman scattering will help identify organic compounds and minerals at very low concentrations.
- PIXL — Planetary Instrument for X-ray Lithochemistry — will search for chemicals, chemical imprints and minerals. Similar to SHERLOC but uses X-rays and measures X-ray fluorescence.
- SuperCam — an instrument suite that can provide imaging, chemical composition analysis, and mineralogy in rocks and regolith from a distance. One of the instruments uses a pulsed laser to heat small amounts of the target to around 18,000 degrees Fahrenheit and analyzes the resultant plasma.
- MOXIE — Mars Oxygen In-Situ Resource Utilization Experiment — will produce oxygen from Mars’ atmosphere. MOXIE will use an electrochemical process to separate Oxygen atoms from Carbon Dioxide. MOXIE operates at 800° C, requiring a sophisticated thermal isolation system, including input gas preheating and exhaust gas cooling. The prototype will make about 6 to 10 grams of oxygen per hour - just about enough for a small dog to breathe.
- MEDA — Mars Environmental Dynamics Analyzer — a weather station to monitor wind direction and velocity, local temperature and humidity, and the amount and size of dust particles in the atmosphere. On Mars, dust drives chemical processes on the surface and in the atmosphere, it affects temperature and weather, and is a hazard to rovers and humans.
- RIMFAX — Radar Imager for Mars’ Subsurface Experiment — ground penetrating radar to study the internal structure of Mars.
- Mastcam-Z — super zoom stereo camera. Can build 360-degree color and stereo panoramas for rover driving and science.
- A total of 23 cameras and 2 microphones.
Main Computer
Processor : BAE RAD750 radiation-hardened PowerPC 750, 133 - 200 MHz clock speed.
Memory : 2 GBytes flash memory, 256 Mbytes DRAM, 256 KBytes eeprom read-only memory.
Our smart phones have lot more processing power and memory than that.
Communications
Antenna |
Antenna Type |
Frequency band |
data rates |
Notes |
Ultra High Frequency Antenna
|
Quadrifilar helix |
400 MHz |
up to 2 Mbps |
relay via orbiter |
X-Band High-Gain Antenna |
30 cm, planar array patch antenna, steerable |
7 to 8 GHz |
up to 800 bps transmit
up to 3000 bps receive
|
direct to earth |
X-Band Low-Gain Antenna |
Omni-directional |
7 to 8 GHz |
up to 30 bps receive
|
direct to earth |
By comparison, most WiFi networks at home operate between 50 and 200 Mbps. Newer WiFi routers operate at up to 1 Gbps.
Orbiters that will relay data include NASA’s MRO, MAVEN, Odyssey, and ESA’s TGO. During landing, direct communications using the X-band antenna will not be possible since Perseverance will not be directly visible from earth.
Power
Like Curiosity, Perseverance is powered by a multi-mission radioisotope thermoelectric generator (MMRTG) which uses 4.8 kilograms of plutonium dioxide as a steady source heat that is converted to about 110 Watts of electrical power using thermocouples. Percy will be the first rover to use Pu-238 created by Oak Ridge National Laboratory; earlier missions used Pu-238 from Russia after U.S. production stopped in 1988.
Two lithium-ion rechargeable batteries provide energy storage. Each rechargeable lithium-ion battery (from EaglePicher) is a 28-volt battery weighing 27 kg and contains eight 43-amp-hour cells in series.
The rover Opportunity used solar panels for power and could not survive a prolonged dust storm two years ago.
Mission Cost
NASA has invested approximately $2.4 billion to build and launch the Mars 2020 Perseverance mission. The estimate to land and operate the rover during its prime 2-year mission is approximately $300 million.
Credit for the mission goes to the Obama/Biden administration. The Mars 2020 mission was announced by NASA on 4 December 2012 at the fall meeting of the American Geophysical Union in San Francisco and details were fleshed out between 2013 and 2015.
About Mars and Life on Mars
Here are some vital statistics about Mars -
|
Earth |
Mars |
Diameter |
12,755 km |
6,791 km |
Mass |
|
10% that of earth |
Gravity |
|
0.375 that of Earth |
Average Distance from Sun |
149 million km |
228 million km |
Length of Year |
365.25 Days |
687 Earth Days |
Length of Day |
23 hours 56 minutes |
24 hours 37 minutes |
Tilt of Axis |
23.5 degrees |
25 degrees; hence has seasons |
Temperature |
Average 57 degrees F |
Average -81 degrees F |
Atmosphere |
78% nitrogen, 21% oxygen, 0.04% carbon dioxide, 0.93% argon, others, water |
96% carbon dioxide, 1.93% argon and 1.89% nitrogen and traces of oxygen and water |
Atmospheric pressure |
|
0.6% that of Earth |
Temperature at Perseverance's landing site will range from -88oC at night to about -23oC in the afternoon.
Life on Mars
The search for life is of profound importance for humankind. Did life arise on earth and earth alone? If so, why did it not arise in places like Mars and other planets? What is the probability of it arising in the trillion of planets out there? What does it take for life to arise and take root?
To date, no proof has been found of past or present life on Mars or any other solar system body.
Mars is an arid and cold world with a very thin atmosphere although it has significant frozen and underground water and CO2 resources. The thin atmosphere prevents liquid water from residing permanently on its surface. Mars lacks a magnetosphere to block the solar wind. Martian surface material is rich in perchlorates which are toxic to microorganisms. For these reasons, there is little hope of finding current life on the surface of Mars.
Several billion years ago, conditions on Mars were likely conducive to harboring life; it may have had a denser atmosphere and a significant water ocean covering perhaps 30% of the northern hemisphere.
It is estimated that Mars lost its atmosphere after it lost its magnetosphere 3-4 billion years ago, possibly because of numerous asteroid strikes. Consequently, the solar wind interacted directly with the Martian ionosphere and stripped away atoms from the outer layer. The relatively low mass of Mars means that atoms and molecules require a lower velocity to escape from the gravitational pull of Mars. This would in turn have resulted in evaporation and loss of its surface liquid water over time. Mars cannot retain water vapor, ammonia or methane in its atmosphere due to its low mass and the low escape velocity of the molecules.
There is water on present-day Mars, especially at the two polar ice caps. More than 5 million km3 of ice have been detected at or near the surface of Mars, enough to cover the whole planet to a depth of 35 meters.
Methane has been detected in the Martian atmosphere. It is estimated that Mars must produce 270 tonnes per year of methane. Methane can exist in the Martian atmosphere for only a limited period before it is destroyed—estimates of its lifetime range from 0.6–4 years. Its presence despite this short lifetime indicates that an active source of the gas must be present. Volcanic activity, cometary impacts, and the presence of methanogenic microbial life forms are among possible sources.
In 2013, an analysis of a sedimentary rock sample collected by NASA's Curiosity rover near an ancient stream bed in Gale Crater showed ancient Mars could have supported living microbes. It identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon — some of the key chemical ingredients for life — in the drilled out powder.
In 2018, NASA reported that the Curiosity rover had found evidence of complex organic compounds from mudstone rocks aged approximately 3.5 billion years old from a dry lake in Gale crater. Some of the molecules identified include thiophenes, benzene, toluene, and small carbon chains, such as propane or butene.
In 1976, one of the experiments in the NASA Viking Mars landers gave a positive result for metabolism and extant life on Mars. The results have been hotly debated even to this day, although the overall consensus is that the results were inconclusive.
If life exists or existed on Mars, evidence of it would most likely be found, in the subsurface, away from present-day harsh surface conditions. Exploring the sub-surface would require a more complex mission. Short of that, exploring sediments in river deltas seems like a winning idea.
How to Identify Life on Mars
This slide from a NASA presentation illustrates the challenge of finding signatures that conclusively identify life vs those that can be explained by non-biological processes. Biosignatures in ancient rocks include presence of organic material, material created by microbes and textures and imprints created in rocks by microbes.
From mars.nasa.gov/… -
Microbes change the texture and chemistry of their environment. Your mouth is one example! Think about the plaque your dentist scrapes off your teeth. That hard stuff is minerals left behind by millions of bacteria. It's an example of a "biofilm." Biofilms form when a group of microbes stick together to form a surface. You can find biofilms on surfaces everywhere in nature. Rocks can preserve their texture and chemistry.
Besides looking for chemicals and organics, the PIXL instrument can detect fine-grained textures and possible signs of biofilms made by ancient microbes.
From mars.nasa.gov/… —
An enduring hope of the science team is to find a surface feature that couldn’t be attributed to anything other than ancient microbial life. One such feature could be something like a stromatolite. On Earth, stromatolites are wavy, rocky mounds formed long ago by microbial life along ancient shorelines and in other environments where metabolic energy and water were plentiful. Such a conspicuous feature would be difficult to chalk up to geologic processes.
From www.caltech.edu/… —
We know some factors that tend to be good recorders of biological activity: basically anywhere new minerals like carbonate salts are forming. These minerals can template and encapsulate pieces of their environment as they form and have preserved microbial fossil information on Earth. Carbonate salts are theorized to be in Jezero Crater, so we're intensely interested in collecting any samples of carbonates that we find to see if these preserve textural evidence of life. We'd also look for organic biomarker compounds, which are sets of molecules whose production is highly unfavorable without the help of biology; molecules like cholesterol in our own cells are examples of this.
There are a ton of proposed biosignatures. Many are not unique to life, or diagnostic of life, but certainly suggest it, because we can't think of another way that they could be made without a cell.
The instruments required to definitively prove that microbial life once existed on Mars is too large and complex to bring to Mars, hence the sample return part of the mission.
Other Spacecraft arrivals at Mars this month
This is the last of 3 missions to arrive at Mars this month. First was an orbiter mission from the UAE, followed by the TianWen-1 spacecraft from China. Unlike Mars 2020, TianWen-1 includes both an orbiter and a rover. The rover is smaller than Perseverance, about 25% in weight. TianWen-1 will attempt to land its rover in May.
Epilogue
I hope this info was useful in helping you understand a bit more about the Mars 2020 mission, about Perseverance and Ingenuity and what to expect during the landing minutes and in the days to follow. Feel free to explore the references cited below to dig deeper.
I will open up a live-blog diary Thursday afternoon, if needed; I suspect there will be a few other kossacks who will be inspired to publish diaries about this exciting event.
Please share you insights, knowledge and questions below. Please note that this mission is not about Elon Musk or his plans to colonize Mars, so let’s stay away from that topic. This mission is about robotic exploration of our Solar system and the quest for knowledge about the origins of planetary systems, about life and about the mysteries of the Universe.
Webcast link —
Coverage starts at 2:15 p.m. ET.
Further Reading
- Mission website — mars.nasa.gov/…
- Mars 2020 overview — www.jpl.nasa.gov/…
- Mars 2020 Perseverance Press Kit — www.jpl.nasa.gov/...
- Mars 2020 rover mission of NASA/JPL — directory.eoportal.org/…
- MARS 2020 MISSION DESIGN AND NAVIGATION OVERVIEW — trs.jpl.nasa.gov/...
- Perseverance (rover) — en.wikipedia.org/…
- Jezero (crater) — en.wikipedia.org/...
- Life on Mars — en.wikipedia.org/...
- NASA Rover Finds Conditions Once Suited for Ancient Life on Mars — www.jpl.nasa.gov/…
- NASA Finds Ancient Organic Material, Mysterious Methane on Mars — www.nasa.gov/...
- Mars 2020 launch with Perseverance and Ingenuity, July 30, 2020 — www.dailykos.com/...
- Mars Landings: Successes and Failures — www.dailykos.com/...
- Why Go To Mars? And other Planets and Moons. — www.dailykos.com/…
- Turn Mars Blue? — www.dailykos.com/…
- Is There Life on Mars? - www.dailykos.com/…
P.S.
All’s well that begins well.