astronomy

Mission Extension Vehicle

Mission Extension Vehicle is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mission Extension Vehicle rather than just read about it. In short: The Mission Extension Vehicle (MEV) is a spacecraft that extends the functional lifetime of another spacecraft through on-orbit satellite servicing. They are 2010s-design small-scale in-space satellite-refueling spacecraft first launched in 2019.

Key takeaways

Mission Extension Vehicle belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mission Extension Vehicle to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mission Extension Vehicle from memory before moving on to harder problems.

Reference excerpt

The Mission Extension Vehicle (MEV) is a spacecraft that extends the functional lifetime of another spacecraft through on-orbit satellite servicing. They are 2010s-design small-scale in-space satellite-refueling spacecraft first launched in 2019. The MEV spacecraft grew out of a concept proposed in 2011 by ViviSat, a 50/50 joint venture of aerospace firms US Space and Alliant Techsystems (ATK). The joint venture was created in 2010 for the purpose of designing, producing and operating the MEV program. Since the original conception of the MEV program by the ViviSat company, the Vivisat venture was shut down for a time, and the company was dissolved by Orbital ATK in April 2016. The MEV program continued on as a solo-project of Orbital ATK, which was subsequently purchased by Northrop Grumman in 2018. The MEV program continued under Northrop Grumman and in 2019, launched MEV-1 to dock and reposition Intelsat 901, an objective reached in April 2020. Servicing an on-orbit satellite in this way was a space industry first for a telerobotically operated spacecraft, as satellite servicing had previously been accomplished only with on-orbit human assistance in the several missions to service the Hubble Space Telescope.

History ViviSat proposed the Mission Extension Vehicle (MEV) concept in 2011. At that time, the project was planned to be a 50/50 joint venture of aerospace firms US Space and Alliant Techsystems (ATK), to operate as a small-scale in-space satellite-refueling spacecraft. In the joint venture, ATK was to be responsible for the technical design, production and operation of the satellite, and US Space would be responsible for the financing and business-side of operations. By March 2012, ViviSat was finalizing its design and was "ready to build" the servicing spacecraft, but had announced no customers for the Mission Extension Vehicle services. In April 2014, ATK announced that it would merge its Aerospace and Defense Groups with Orbital Sciences Corporation. In the timeframe 2013–2016, the partners ATK and US Space fell out concerning the joint ViviSat-venture. The situation ended with ATK (which in the meantime in 2015 had merged with Orbital Sciences Corporation to become Orbital ATK) taking control and dissolving the ViviSat-company on 5 April 2016. The MEV program continued as Orbital-ATK only project. In December 2017, the US telecommunications regulator approved a plan submitted by Orbital ATK to use an MEV to service an Intelsat satellite, Intelsat 901, that was originally launched to geostationary orbit in June 2001 for a planned in-service life of 13 years. That satellite had already been replaced in orbit. The first MEV, MEV-1, was then planned to launch with Eutelsat's Eutelsat 5 West B commsat, no earlier than 2019. MEV-1 also needed a licence from National Oceanic and Atmospheric Administration (NOAA). The NOAA license is required because the MEV-1 has cameras for docking that could also image the Earth, thus necessitating a remote-sensing license. In 2018, Orbital ATK was acquired by Northrop Grumman to become Northrop Grumman Innovation Systems. The MEV program continues under this new company. MEV-1 was set to launch on a Russian Proton-M rocket along with Eutelsat 5 West B satellite on 30 September 2019, but the launch was postponed to 9 October 2019 due to issues with the integration of control systems of Briz-M orbit insertion stage and the satellites. MEV-1 was launched on 9 October 2019. MEV-1 rendezvoused with Intelsat 901 on 25 February 2020 at 07:15 UTC, and by April 2020 had repositioned the commsat so that it could come back on line in its designated geosynchronous spot, a space industry first for a telerobotic spacecraft, and something that had only previously been done on the Hubble Space Telescope servicing missions with direct human assistance. The goal is to extend its operational life by five years via in-orbit stationkeeping. At the end of the five-year mission extension, MEV-1 was used to move the spacecraft back to the graveyard orbit and undocked. The spacecraft will return to GEO for Optus D3, the next target. It is designed to be able to dock and undock additional times, potentially enabling it to service additional satellites.

Missions

Technical capabilities and competition ViviSat saw competition for space servicing business with the 2011 announcement of the Space Infrastructure Servicing (SIS) vehicle from MacDonald, Dettwiler and Associates (MDA). However, the two vehicles intended to operate with different technology approaches. Whilst the ViviSat design connects to the target satellite and uses "its own thrusters to supply attitude control for the target"., SIS MDA would open the satellite's fuel lines, refuel it, then depart. In a June 2012 article in The Space Review, a number of approaches to satellite servicing were discussed. ViviSat's Mission Extension Vehicle was reported to operate at the "less complex" end of the technology spectrum, which could offer higher reliability and reduced risk to satellite owners. ViviSat believed their approach was simpler and could operate at lower cost than MDA, while having the technical ability to dock with "90% of the 450 or so geostationary satellites in orbit", whereas MDA SIS could open and refuel only 75%. "In addition to extending the life of an out-of-fuel satellite, the company could also rescue fueled spacecraft like AEHF-1 by docking with it in its low orbit, using its own motor and fuel to place it in the right orbit, and then moving to another target". As of 2012, ViviSat planned to use the ATK A700 satellite bus.

Worked examples

Example 1 — a first encounter with Mission Extension Vehicle

Start with the simplest possible case. Write down what Mission Extension Vehicle claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mission Extension Vehicle before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mission Extension Vehicle ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mission Extension Vehicle

In research: Mission Extension Vehicle appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mission Extension Vehicle in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mission Extension Vehicle is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2019 in the United States, Northrop Grumman spacecraft, Orbital Sciences Corporation, so understanding it makes those chapters shorter.
In everyday life: Look for Mission Extension Vehicle outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mission Extension Vehicle in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mission Extension Vehicle means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mission Extension Vehicle out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mission Extension Vehicle in simple terms?

Why does Mission Extension Vehicle matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mission Extension Vehicle?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mission Extension Vehicle.