NASA's InSight spacecraft is expected to touch down on the surface of Mars tomorrow (Monday, Nov 26) at around 3 p.m. EST. Much has been written about the mission, both at NASA, in scientific papers and in popular science media. Here we present some summary information to guide those who may be unfamiliar with the mission and links to web sites for more detailed info.
A Summary
Item |
Description |
Insight Acronym |
Interior Exploration using Seismic Investigations, Geodesy and Heat Transport |
Launch Date |
May 5, 2018 |
Touch-down time |
Monday, Nov 26, around 2:54 p.m. EST |
Primary Mission |
To study the size, thickness, density and overall structure of Mars' core, mantle and crust, and the rate at which heat escapes from the planet's interior
Also, to measure Mars rotation and wobble using radio signals
No analysis of soil, atmosphere or complex molecules.
|
Mission Type |
Lander, not rover. No wheels.
|
Primary Instruments |
Seismometer and burrowing heat probe
Plus cameras and comm. equipment
|
Size |
6.0 × 1.56 × 1.0 m, deployed |
Power |
600 W, Solar, Li-ion batteries |
Solar Array Deployment |
16+ minutes after landing (after the dust settles down) |
Science Mission Start |
2-3 months after landing |
Mission duration |
2 years on Mars |
Earth-Mars distance on Nov 26 |
146 million km or 8.1 light-minutes. Earth-Sun distance is about the same |
Command and data handling Computer |
Redundant RAD 750 radiation-hardened PowerPC 750, 115.5 MHz; 64 GB flash memory; VxWorks operating system
|
The following video provides an excellent summary of the mission —
The EDL
The 7-minute Entry, Descent and Landing (EDL) sequence is very-well described in Emily Lakdawalla’s article at www.planetary.org/…. Entry starts at an altitude of 125 km with a spacecraft speed of 19,800 km/hour. After a high speed entry, with protection provided by a heat-shield, the spacecraft deploys a parachute to slow down through the thin Martian atmosphere; the final descent is made using thrusters, with a landing speed of 8 km/hour.
The following diagram from the article illustrates the landing sequence along with key operational parameters.
The following beautifully rendered animation from Lockheed shows the landing sequence —
Weather Forecast
The local solar time at the landing site in the Elysium Planitia area of Mars will be about 2 p.m. at touchdown (2:54 p.m. EST). If it is a relatively clear day -- no dust storm -- the forecast calls for air temperature at the height of the lander deck to reach a balmy 18°F (minus 8°C) that afternoon and plummet to about minus 140°F (minus 96°C) overnight. planetary.s3.amazonaws.com/...
The CubeSats
The two independently flying CubeSats MarCO-A and B will relay UHF radio band signals during InSight's EDL, from the lander to Earth. The 30 cm × 20 cm × 10 cm spacecraft will not enter orbit but fly past Mars. The CubeSats are not critical for this mission, but are part of a technology demonstration, which will be useful in future missions.
What To Expect during EDL
NASA will cover the event live on NASA Television, the agency's website and various social media platforms. Coverage will begin at 2 p.m. EST. Follow @NASA and @NASAInSight for #MarsLanding news. See a list or an interactive timeline of landing milestones. News briefings and launch commentary will be streamed on NASA TV, YouTube.com/NASAJPL/live and Ustream.tv/NASAJPL.
About 30 seconds after cruise stage separation, the entry vehicle will begin turning toward the orientation required for atmospheric entry, with the heat shield facing forward. The turn will take about 70 seconds. Within the last two minutes before entry, the wrap-around patch antenna will begin transmitting data at 8 kbits per second, in the ultrahigh frequency (UHF) radio band.
The twin MarCO spacecraft will relay EDL signals immediately to Earth. It will take 8.1 minutes for the signals to travel 146 million km to Earth.
NASA’s Mars Reconnaissance Orbiter (MRO) will also relay InSight telemetry data to Earth, but after an hour or two of store-and-forward delay, after it swings around the far side of Mars. The Mars Odyssey orbiter will also participate in relaying data sent after the landing.
The EDL signals will also be directly detected on Earth, although they will be too faint to decode, but they could provide some basic indication of EDL progress, if the CubeSats fail to operate.
At the top of each of InSight’s legs is a trigger sensor; when the surface pushes up the leg and hits the trigger, it shuts off the lander’s retrorockets. It also sends out two signals that touchdown has been achieved: a “tone beacon” through its UHF antenna and a “beep” through its X-band antenna. This X-band “beep” is expected to turn on about 7 minutes after landing, and will be a clear indicator that InSight is functional on the surface.
On Earth, two radio telescopes will be listening for the tone beacon and provide a basic indication of InSight’s status.
Needless to say, there will no cameras on site, to provide live visual coverage. If all goes well and if the CubeSats are alive, we may get the first pictures from InSight’s cameras within minutes after landing.
The Landing Site
Unlike the Mars rover missions, there is no special/interesting place for InSight to land on. The 130x27 km site Elysium Planitia was chosen for practical reasons and to minimize risk — low elevation, near equator to maximize solar energy, and a flat relatively rock-free area.
Instruments
InSight carries two primary science instruments -.
- The Seismic Experiment for Interior Structure (SEIS) to take precise measurements of quakes and other internal activity on Mars.
- The Heat Flow and Physical Properties Package (HP3), a self-penetrating heat flow probe, that will burrow up to 5 m into the ground while trailing a tether with embedded heat sensors.
The following video shows in more detail the delicate deployment of the two instruments using the robotic arm.
The Journey to Mars
The journey to Mars took 6.7 months traveling a distance of around 484 million km. Note that Mars’ orbital period is 687 Earth days; since launch time, Earth has advanced more than 180o around the Sun, while Mars has advanced around 120o.
Epilogue
This will be yet another exciting day for Science; it will also be a harrowing day for many, since there are many things that can go wrong in the difficult 7-minute EDL part of the mission. Landing on Mars is hard; landing missions by every other country have all failed. It will also be a good day to escape from the ugly political reality-show we are all living through.
Update
InSight made a successful landing at its appointed time. Both MarCO CubeSats performed exceptionally well, beaming back EDL telemetry in real-time. Here is a 360 degree video of the coverage; the landing occurs at the 55:52 mark.
The comments section has additional information about the nerve-wracking and exciting event.
Further Reading
- NASA InSight site — www.nasa.gov/…
- Mars InSight Landing Press Kit — planetary.s3.amazonaws.com/…
- How NASA Will Know When InSight Touches Down — www.nasa.gov/...
- What to Expect When InSight Lands on Mars, Emily Lakdawalla — www.planetary.org/…
- InSight wiki — en.wikipedia.org/…
- InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) — directory.eoportal.org/...
- Why Go To Mars? And other Planets and Moons. — www.dailykos.com/…
- Turn Mars Blue? — www.dailykos.com/...
- Mars Landings: Successes and Failures — www.dailykos.com/…
- Is There Life on Mars? — www.dailykos.com/...