Chief, need a ride to the orbit! About delivering microsatellites to space; Part 1
Nano and microsatellites have already become the largest mass spacecrafts. However, challenge of its delivery to space is increasing. There are several ways to launch small satellite:
- As a payload on a ‘big’ satellite with a light, medium and heavy carrier rockets;
- During cluster launch of the light carrier rockets;
- From the board of a space vehicle (unmanned or manned) and International Space Station (ISS) — manual by astronauts during extravehicular activity, or with the use of special deploy systems;
- With the use of specially allocated nanolaunchers.
Until now, only first three ways were being used because nanolaunchers have not yet been created (plagued by some serious technical and economic problems). It is interesting that all three ways are cluster, in one way or another, as they foresee simultaneous launch of more than two vehicles (even of different types). In recent years as a good example can be launching missions of the whole batch of nano- and microsatellites (two or three dozen at the same time) carried by “Dnepr”, Taurus or Falcon-9 rockets. At the end of 2014 company Orbital Sciences launched cluster of a 29 microsatellites, then Russian company Cosmotras send to the orbit 32 crafts at once and in January 2015 another 33 SSC arrived at the ISS, which were launched from the station after.
Cluster launch: pros and cons
Cluster launches are for now a lot cheaper than other ways to launch a craft but their common flaw is an initial dependence of the craft from the time and orbit of the main satellite. Usually these facts result in long period of waiting and possible start and launch delays, which is not optimal for achieving the objectives. For the training crafts the last problem is less important because it’s crucial for them to get to the orbit, no matter which one. Although a problem arises because of that: crafts are designed by one student and implemented by others. It demotivates developers, decreases efficiency of a training process, increasing its duration in an unreasonable way.
Besides, this problem is not that harmless: in case if cubesat was made under the PK-98/PK-11 standard, such craft has a certain period of storage time, and if it is expired a full-round testing of the satellite is needed.
For targeted cluster launches problems related with a launch delay and suboptimal orbit are absent (if cluster consists of one-kind crafts, for example, used for forming of the communication or navigation satellites group — OneWeb, Orbcomm, O3b, Globalstar, Glonass or Galileo). However, although cluster allows to establish an orbital group, quick and cheap, its revival becomes a tough challenge, especially when satellites should be launched on different orbital surfaces: there should be either separate launch, or a proper “travel companion”. In the end, there are options of planned waiting of the sufficient degradation of the batch of the same kind satellites’ of the new generation.
There are some other disadvantages. For example, if carrier rocket crashes all of the cluster satellites will be destroyed, which may result in a sufficient damage to the processes of forming a group or its maintenance. That happened to the connection system Globastar, when in September 1998 due to the failed carrier rocket Zenith-2 launch, 12 satellites were lost , which is a quarter of the orbital group. That led to delay of system deploy and to a partial loss of compatibility.
Simultaneous launch of the large satellites group consisting of SSC of different types can require non-standard solutions with the use of different adapters and dispensers which complicate launch system and usually decrease its possibilities regarding payload mass. On the other side, universal P-POD — type dispenser for the cubesat deployment (three of a 1U kind, and one of 3U) has a mass of 2–3 kg, which is comparable to its own weight (3–6 kg). In other words, usage of dispensers and other devices for satellites deployment during cluster launch leads to the sufficient increase of unit cost — that is “cost for a satellite’s adaptation to the carrying vehicle”.
Despite of the aforesaid disadvantages, cluster launches are still very perspective and popular.
Classics: launch on Dnepr
ISC Cosmotras, being a carrier rocket Dnepr operator continuous to be a trustful supplier of the launch services for microsatellites developers. Company uses well-established technology of work with Russian and foreign (over 30 countries) clients: with the minimum comprehensible set of procedures for approving of documents, technical requirements, interfaces; there are also typical adapters with flight qualification for satellites of different types, and a transparent structure of launch pricing. It is also important to have a comfortable accommodation of the client on the launch base and all of needed work conditions on the assembly and testing facility. Timing of the Dnepr launch usually is about couple of months because the main payload is developed by foreign developers, which means that satellite shall be delivered to the trial space on time.
Carrier rockets of the Soyuz kind as a travel companion to the orbit
Today the new programs of using a Soyuz carrier rockets with medium transport capacity as a tail payload carrier become more and more popular. Payloads usually are launched on low and sun-synchronic orbits, which made them so attractive for designers and users of ISS.
Basic limitations for usage of that system are following: most of the Soyuz launches is executed under the Russian Defense Department order, or flight programs, or under foreign orders from French Guiana.
So during the period from 2008 to 2015 there were about 123 launches of Soyuz carrier rockets from three different spaceports (Baikonur, Plesetsk, Guiana), that is a 15–16 launches a year. From Baikonur it was 80 rockets, for Plesetsk — 30 and 13 from Kourou.
36 automatic cargo space ships of Progress type and 30 piloted transport ships of Soyuz type were launched under piloted space program.
There were 30 launches under defense programs; 27 — under scientific, national-economy and commercial programs. 19 of them were carried in foreign clients interests.
So, theoretical opportunity of tail launches of domestic training and researching nano-satellites were only 8 times (6.5 % of total launches). In the other cases it would be challenging to place an extra payload under the nose fairing of the rocket.
Due to different reasons, launches of scientific and national-economy payloads were carried the last (after military and piloted crafts), and with these missions there were delay in the launch time, running in some cases to several month or even years. Regarding this statistics it is obvious that we can hardly bet on Soyuz as a cheap carrier for the tail launches, especially for company, building its business-strategy on satellites.
Nevertheless potential opportunities should be considered.
From Soyz developers: Progress RSC
Under initiatives of I. V. Belokonov (the Academician S.P. Korolyov State Aerospace University ) engineers from Samara suggest to place tail payloads into free spaces of the third stage (I pack) of the Soyuz -2 rocket.
There is a space for it in the adapter module, used for the docking of the I pack and space re-entry part, where it is possible to place a SSC and other payloads, without influencing on its features and to the main task completing. Considering planned nature of the most of Soyuz-2 carrier rockets launches with the I pack, which is conditioned by rigid timelines of the ISS service, it was decided to suggest client a unique work principle, that allows to plan ahead and choose separately the time of the launch with I pack of Soyuz.
Disadvantage of this method is a low height of the orbit for the ‘travel companion’ — 250 km. Due to that, term of existence of the satellites, launched as a ‘tail’ is limited to a few days. Besides, usage of the I pack for verification of technologies in space conditions means other control and navigation challenges. For example, it is necessary to change rocket’s cyclic graph , meaning control system logic on the last section of the flight, causing delay of enabling or even ignore mode of the third stage twisting after the separation of the main payload. Specialists suggested options of choosing cyclic graph and SSC separating speeds from the stage during a multiple launch for the safety of separated satellites movement, but that still needs a flight practice. After the flight trials with a positive results this method can be useful for underloaded missions.
As an alternative for I pack launch can be used a cubesat-container developed by Progress RSC and built on Volga booster. This is a main technique suggested by Samarians to potential clients, it allows launches on the orbit with the height of 1500 km (or 800 km for sun synchronized orbit). That is the way which companions of the carrier rocket Soyuz-2 will be launched from the Vostochny spaceport on spring 2016, SamSat-218 (Samara) in particular.
The third option from Progress RSC is a launch of cubesats and small satellites as a tail payload on an external adapter of Bion-M and Foton-M satellites. First tail launches were carried that way in 2013, when ISS Aist (SSAU) and several foreign cubesats: Beesat 2,3 (BTU), one of the first Pigeons (Planet Labs) and some others were launched to the orbit. Advantages of this way are: orbit height 500..600 km and due to that, a long term of ballistic existence of the satellites; disadvantage is the fact that launches of Bion and Photons happens very rare.
From Glavcosmos and Skolkovo
JSC Glavcosmos suggests space crafts’ launch as a tail payload on the adapter of the Fregat booster (NGO named after Lavochkin). Along with the main payload it is possible to launch several microsatellites or cubesats on board of the Soyuz-2, modernized vehicle. First launch took part on September 14, 2009, when Russian microsatellites Sterh, Tatiana-2, Blitz, Iris and also a ZA-002 (SA) with a spacecraft Meteor-M №1 took off on a carrier rocket Soyuz-2.1b. It’s been three trial launches like that, including several cubesats. Same technique will be used during the launch of two 6U-cubesats Cubesat-NANO (Dauria Aerospace) and a Russian 3U-cubesat Mayak in 2016.
Another opportunity for tail launch of cubesats emerged with creation of the Progress-MS next modification (automatic transfer cargo vehicle), which first launch was successfully carried on 21 December 2015 from the spaceport Baikonur. It is represented on a tail launch market by Skolkovo center of orbital launches (subsidiary enterprise of SKOLKOVO Foundation). Previous versions of Progress have already been used for microsatellites’ launch, but only as a scientific-educational experiments on a Russian segment of ISS. Particularly, in November of 2001 a pioneer of such program — Russian-Australian craft Colibri — 2000. In January 2012 with the use of special container, microsatellite Chibis-M (developed by Space Research Institute RAoS in cooperation with SPUTNIX specialists ) has been launched. Crafts were released from the load compartment hatch of the transfer vehicle after its completion of the main project task. Special container’s system was developed by the Special design office of the SRI RAoS (Tarusa) under the leadership of V.N. Angarov within RSC Energy order.
But soon technology of detaching will be changed. Four special launching containers (with a number of cubesats up to eight in it) will be built near the backup ring of the technical compartment of the new cargo crafts. They will be delivered to the orbit during Progress MS flight to the station, with the use of a spring. As it is almost always possible to get an extra 5–10 kg during load crafts launches to the ISS, this way of launch increases chances of educational and scientific companies, creating satellites of nano- class under CubeSat standarts. Advantages of this way are: higher frequency of flights (almost 30% of all launches during that time, or 4–5 a year) and clear reliance of crafts’ launch to the plans of Federal Space Agency with the minimal time shift (all other things being equal).
As a disadvantage of this way we can name a constant inclination of the orbit of the tail launched satellites — 51.6 o , which is not convenient for the RF territory observation and for craft control from mid-latitude regions. Besides, there is no information about project status (from technical and administrative points) and how much time the final negotiations about program launch with RosCosmos and RSC Enrgy can take.
Conclusions
Possibilities of the launches from the ISS will be in our next review.
I. Borisov, S. Karpenko, Private space company of Russia “Sputnix”
