Mars 2020 | Atlas V 541


Featured Image used with permission by Trevor Mahlmann

Graphic by Geoff Barrett Rocket by Stanley Creative

What does this all mean?

We lifted off for MARS! Yes you read that correctly, NASA has spent years developing its next piece of hardware to make the daring trek to the red planet. The rover dubbed Perseverance launched from the the East Coast of the United States and in around six months to land on Mars.

What does the Mars 2020 mission look like?

NASA has chosen United Launch Alliance (ULA) to launch the 1,025 kg (2,260 pound) rover on its six month long journey to the Red Planet. The overall mission has been divided into four segments by NASA: Launch, Cruise/Approach, Entry-Descent-Landing (EDL) and Surface Operations.

Atlas V Launch

ULA’s Atlas V 541 (more on what that means later) lifted off from SLC-41, CCAFS at 9:35 am EDT with the Perseverance rover in its 5 meter fairing. Climbing to an initial orbit of 270 km (167 miles), the Centaur upper stage then boosted the rover towards Mars. It is important to note that there is a one month period where the position of Earth and Mars are aligned perfectly for a transfer. After this period ends, the teams will have to wait for about 26 months before a new opportunity opens up. However, NASA has expressed interest in a contingency plan after the window is up.

Perseverance Cruise/Approach

Surprisingly, this six month phase has a lot more to it. The only part of the spacecraft left is Perseverance which is enclosed in its aeroshell. This shell acts as protection, but also hosts the power and course correction propulsion systems. Throughout this time, mandatory health and communications checks will be performed by NASA’s specially trained team of engineers and mission specialists. Towards the end of this phase, preparations will begin for the Entry, Descent and Landing (EDL).

Mars 2020 Entry, Descent and Landing (EDL)

Also known as the “7 minutes of terror”, this phase of Perseverance’s flight can be some of the most nerve wracking for the team and space fans. Due to the fact that Mars is so far away from Earth and communications are limited to the speed of light, the transmission signals can take about 20 minutes to reach Earth. That’s a 40 minutes round-trip. All the data that the teams see happened 20 minutes ago. By the time we see the spacecraft enter the Martian atmosphere it could already have landed, or crashed.

Entry – 10 minutes Cruise stage separates and burns up in the Martian atmosphere
Entry +/- 0 minutesEntry into the Martian atmosphere begins
Entry + 80 seconds At roughly 2,100 degrees Celsius, the heat shield experiences maximum heating 
Entry + 90 secondsThe craft experiences the maximum deceleration. Slowing down from 21,200 km/h (13,200 mph) to just 1600 km/h (1,000 mph) in only two and a half minutes
Entry + 240 secondsThe parachute deploys at and altitude of 9 to 13 km (6 to 8 miles)
Entry + 260 secondsHeat shield separation and the ground radar systems activate to define a suitable landing area
Entry + 350 secondsBack shell separation as the rover begins a moment of freefall before the landing motors on the Skycrane ignite
Touchdown!At around 21 meters (70 feet), the rover separates from the landing stage tethered to it by three nylon ropes and is gently set down at 2.7 km/h (1.7 mph). The landing stage then flies away and crashes into the surface at a safe distance.

Surface Operations

In the final and longest stage of the mission we have Surface Operations. This includes everything from the moment Perseverance touches down, to when it can no longer function. The mission is scheduled to last about one Martian year, or 687 Earth days. However, the team will often refer to mission days as “Sols” or Martian days. In this case, the mission will last 669 sols. The first 90 sols will consist of initial checkouts of all of Perseverance’s systems to ensure that they are all functioning properly.

The rover will also deploy its antennae and begin taking images of the surrounding surface for the scientists to observe. During this initial period, the team will be on Martian time, which means starting their shifts 40 minutes earlier each day because one Sol is approximately 40 minutes longer than one Earth day. Another major event on Mars 2020 is the technology demonstration of the Ingenuity drone. After deployment, the team will conduct a series of tests to prove that the drone is ready for normal operations. Keep in mind, this is the first time a drone had been on Mars, or any other planet other than Earth.

Keep an eye out on the Mars 2020 website for future updates on surface operations after touchdown!

So what about the actual payload?

The payload consists of the Perseverance rover and the attached drone, Ingenuity. The Perseverance rover is by far the most complex and most technologically advanced piece of hardware to travel to another planet. Similar in shape/size to the former, still operating, Curiosity rover, launched on November 26, 2011, Perseverance is only 126 kg (278 pounds) heavier and 13 cm (5 inches) longer. Taking a big step up from the Curiosity rover, Perseverance will have similar, but much more advanced instruments focused on sample collection for future return to Earth. Let’s talk about some of the major instruments on the rover.

Mastcam-ZPIXLMEDAMOXIERIMFAXSHERLOCSuperCam
What’s the instruments main purpose?Image the Martian surface in high-definition video, high resolution panoramas and in 3D.Measure the chemical composition of the rocks on the Martian surface at a
finite scale. 
Act as a mini weather station on PerseveranceDemonstrate carbon dioxide to oxygen conversion for
future human exploration of the red planet. 
See sub-surface features using ground penetrating radarDetect minerals, potential biosignatures and organic molecules
on a very finite scale.  
Study the atomic and molecular composition of rocks and soil
Where on the rover is it located?The mast at about 2 meters (6.5 feet) highThe turret at the end of the robotic arm.The neck of the mast and on the front of the body of
Perseverance.
The front right side, inside the rover.The lower rear of the rover as a radar antenna. The turret at the end of the robotic arm.The turret at the end of the robotic arm.
How much power does this instrument draw?~ 17.4 Watts~ 25 Watts~ 17 Watts, measurement dependent ~ 25 Watts~ 5-10 WattsTurret: 32.2 Watts
Body: 16.6 Watts
Turret: 32.2 Watts 
Body: 16.6 Watts
What is the data return speed?~ 148 Mbits per sol~ 16 Mbits per experiment
~2 Megabytes per Sol
~ 11 Megabytes per dayn/a~ 5 to 10 Kilobytes per sounding location~ 79.7 Mbits per day~ 4.2 Mbits per day
Any other special information?1600 x 1200 maximum image sizeFrequency range of 150-1200 megahertz; 10 meter (30 feet) depth
The Perseverance rover with labeled instruments.

Ingenuity Drone

Perseverance won’t be traveling alone! It will be accompanied by a drone. This will be the first time that humans have flown anything on another planet. Weighing in at just 1.8 kg (4 pounds), Ingenuity has a few key objectives:

Key Objectives

  • Demonstrate the ability to perform powered flight in the thin atmosphere of Mars
  • Demonstrate the technology of miniaturized flying on another celestial body
  • To operate totally autonomously

Key Features

  • Recharges independently and is solar powered
  • Communicates with Perseverance at a maximum 1 km (0.6 mi) radius, Perseverance then relays the signal back to Earth
  • Two carbon fiber counter rotating 1.2 meter (4 foot) long blades to provide lift in the thin atmosphere
  • Equipped with one color and one black and white camera
The flight model of the Ingenuity helicopter.

What rocket will propel Perseverance to Mars?

The Atlas V

The Atlas V Common Cores are manufactured near Decatur, Alabama and are then transported via the Mississippi river and the Gulf of Mexico to either California or Florida.

What Does 541 Stand For?

The configuration of the Atlas V for the Mars 2020 mission is 541. But what does “541” mean, anyway? The last three numbers or letters in the Atlas V’s name denote the configuration of the rocket. The first number/letter shows the fairing diameter size (in meters, of course) and ‘N’ for no fairing. The number 5 in this case stands for a 5 meter fairing.

The second number determines the number of strap on solid rocket boosters (SRBs). It can range from 0 to 5, and in this case, there are four strapped on to the side of the center common core. The third and final number refers to the number of engines on the Centaur Upper Stage, which can be either one or two. In this case there is one engine. The only time that there has been two engines (on an Atlas V) was on Starliner’s OFT-1. So to summarize, for the Mars 2020 mission, this rocket has a 5 meter fairing, 4 solid rocket boosters, and 1 engine on the Centaur Upper Stage.

Why Are The SRBs Positioned This Way?

It is unique to the Atlas rocket to have their solid rocket boosters (SRBs) positioned in this way, but why is that? When for example 5 SRBs are used, they are positioned with two on one side and three directly opposite of them. If you notice carefully in the image below, there are long and somewhat flat pipes running down the side of the first core stage. These are called raceways and carry fuel from the tanks down to the engines and some carry gases back up to the tanks to pressurize them, so the fuel stays flowing out the pipes. When Atlas was designed, these raceways were placed in their positions without the thought of SRB placement. So when more SRBs were needed, they were placed in the most convenient spot.Notice the cylindrical and flatter pipes that run down the sides of the booster. Those prohibit SRB placement in those areas.

engine atlas v ula raceway piple rocket fuel
Notice the cylindrical and flatter pipes that run down the sides of the booster. Those prohibit SRB placement in those areas.

But you might ask, won’t that offset the thrust and make it fly in the wrong direction? Well, the answer is no. Because the engines on the core stage can gimbal, they counteract that offset of thrust by vectoring their thrust, which is known as thrust vector control (TVC). The SRBs, and most of them for that matter, do not have TVC abilities.A diagram of the entire Atlas V family with the SRB placement for each number shown.

rocket white srb atlas v fairing fuel engine
A diagram of the entire Atlas V family with the SRB placement for each number shown.

Want even more information? Watch Tim’s video on the Perseverance rover!

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